Renoir's Rants

Hand-drill geared extruder

2011-11-20T12:19:00.001Z

I managed to break my original BfB extruder :-(. The acrylic had flexed too many times, and the top retaining bracket broke in half. The screw thread now carefully unscrews itself rather than driving the filament down :-(

So, time to update to a modern wade-style or similar extruder, using a hobbled bolt. Of course, I could have bought the gear drives from the many RepRap shops or ebay, but that's too easy :-).
Instead, I found an old cheap hand drill, with similar sized gearing. It turned out to be on an 8mm shaft.

I added a 5mm to 8mm sleeve to a stepper motor (made from a sex bolt) and drilled and tapped a 4mm hole for a grub screw - I could then attach the smaller gear to the stepper shaft. The larger gear I cut a small square indent to match a carriage bolt, and cut some teeth into the threads using a dremmel cutting disc. A plastic cutting board and an Ikea bracket made a mount, and three skate bearings (8mm 908) made up a channel for the filament.

It's not pretty, and it's heavier than ABS gearing, but it grips the filament like anything - I can't stop it using my full strength grip, and really forces the filament through.

I'm currently building a heater block and nozzle to add on the bottom. Hopefully this 'RepStrapStruder' will last long enough for me to print a proper wade's extruder.

New Megas

2011-11-10T17:03:00.000Z

My new Mega boards arrived - all good.
Simple tests worked fine, but after uploading the RepRap host software at 115200 Baud, had problems connecting and even uploading new sketches. I had to press reset and upload almost straightaway, otherwise the upload failed.

A bit of research suggested an updated Atmega 8u2 firmware (the usb chip). (also the new boards appear as /dev/ttyASM0 instead of /dev/ttyUSB0 - update to the latest RXTX libraries.

Borrowed from a forum post by stimmer on this thread

I saw that a new Uno firmware had been uploaded to the Arduino repository. I've been trying it out, it seems pretty good so far, tools menu and serial monitor are much more reliable and it only failed to program once. (Although the Duemilanove was never perfect either)

I got the firmware from here:
https://github.com/arduino/Arduino/tree/master/hardware/arduino/firmwares/arduin...(click on the right firmware, then click raw, then save it)

Reflashing the firmware on the 8u2 is a little tricky. Don't try this unless you are prepared to risk bricking your board completely!

You need the dfu-programmer utility:
sudo apt-get install dfu-programmer

Then follow the instructions here to get the Uno into DFU mode:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1285962838/10#10

Then to flash the firmware, do this:
sudo dfu-programmer at90usb82 erase
sudo dfu-programmer at90usb82 flash --debug 1 Arduino-usbserial-uno.hex
sudo dfu-programmer at90usb82 reset

Finally unplug the USB plug, wait a few seconds, plug back in.

Also, a good page on the arduino site

Note, that to put reset the Mega 8u2 chip, the reset pins are a bit different: I found instructions for resetting the mega chip.

My mega's accepted the sketches without problem, and both replicatorG and RepRap host connect well at 115200 baud.

Might help if you're getting unreliable high-speed connections to the arduino and you've got a recent board (/dev/ttyACM0)

Arduino Mega board is toast!

2011-11-01T16:28:00.000Z

I have managed to blow my Arduino mega board.
It stopped uploading, and there was a 'hot' smell - never a good sign. Unplugging everything, the arduino chip was very hot indeed.

After waiting for it to cool, I found that plugging it into the USB socket - nothing else - started to make the mega chip warm up, and it got too hot to touch. :-(
Another circuit board is sacrificed to the gods of knowledge and experience.

Tracing things back, I wondered how it happened. My setup hadn't changed, I'd just been running heater and extruder tests - the steppers weren't plugged in, so it was unlikely to be them.

Looking at the my heater board again, I realised that the output pin of the arduino was connected straight to ground through the MOSFET gate - no current limiting resistor. A bit of digging uncovered a possible problem - the design I'd used as a base (RepRap Gen 2/3) had the same circuit, but used current limiting Mosfets. I'd upgraded mine to larger ones, but checking the data sheet, the Mosfet gate acts a bit like a capacitor. Charging the gate could be done slow(with a resistor) or fast. A current of 2A was given as an example to charge the gate in 14nS.

Oh. The arduino pins can only handle 100mA or so. Still, it only does that when it's switched on or off, so long as I wasn't switching it on and off thousands of times a second - like using PWM.... Damn.

Looking back, it's surprising that it coped as well as it did - it should have gone up in smoke straightaway! I'm impressed it worked at all - it coped for several hours of testing. Each time it switched, the arduino pin was directly connected to ground - drawing a big current for a few mS, then when it switched off, the mosfet gate would discharge itself straight through the arduinio pin to ground.

I have now redesigned my heater / Mosfet board to incorporate a 560ohm current limiting resistor (between the arduino pin and the mosfet gate), and also a pull-down 100k resistor between the Mosfet gate and ground. It should limit the current to 90mA, and make sure the gates switch off if the board isn't connected.

I've also ordered a couple of new Ardunios - hopefully I'll be more careful with these...
:-)

Recycling!

2011-10-30T20:58:00.000Z

I've been using the laser toner method for a while to make my PCBs. It seems to work well for me, I print out the PCBs using a Samsung ML2010 laser printer, tape them to a cleaned copper board, then run them through a laminator twice. The heat fuses the toner to the board, and as long as your paper isn't too sticky, you can peel it straight off and etch.

I've been using this successfully, even for larger boards like my Arduino mega shield. The key variable seems to be the paper. I have the best results by cutting a square of sticker backing paper, using the stickers to stick it to the centre of a normal sheet of paper, then printing the PCB from Eagle. This works well, but I do need a sheet of stickers (like the A4 laser printing stickers) every time.

Other people have reported success with tracing paper, or magazine paper. I grabbed some tracing paper (two types, Goldline 63gsm and Goldline 112gsm) paper and gave it a try. It printed well, but didn't stick too well - you need to soak the paper to remove it, and most of my toner came off with the paper. Maybe my laminator wasn't hot enough :-(.

So, I'd run out of labels, my tracing paper experiments weren't working well - and then my eye fell on a discarded Farnell packing bill on my table. The Farnell packing receipts are printed on some sort of fan-fold sticker paper so that the address labels can be removed and stuck to the box. The whole bill is basically one big sticker! I cut a square, stuck it to a sheet of paper using the sticker I'd just removed, and ran it through the printer.

Perfect result, first time! The toner transferred very well to the board:

The finished board (a SMT version of the tiny thermistor circuit) looks great and from the detail (on the lettering) this would work with much finer traces!

I'll start saving up all my old shipping receipts instead of buying printer labels now....

P.S. top tip - after the stickers have been 'laminated' and cooled, if you gently rub the back of the sticker with your thumb, a small 'bubble' forms that gently lifts the sticker backing away from the toner bit by bit. I get almost 100% adhesion with this technique.

Crimptastic!

2011-10-30T20:26:00.000Z

After a few days, my new crimping ~~toys~~ tools arrived in the post. Here's a joint from a couple of years BC (Before Crimptool) :

However, that was before the RVFM HT-225D, which I got from Rapid.

It has the correct 'B' shaped jaws to make proper crimp joints:

To use this effectively, you need a set of crimp pins, and you need to carefully strip and trim the wire, like this :

Then you need to insert a crimp pin into the appropriate jaws - note you don't always need to remove them from the strip, I found them easier to handle by bending a single pin away from the strip.

Then, insert the wire : I marked a small dot with a sharpie to mark the appropriate depth:

Pull the handles together until they're all crimped - rinse and repeat:

So much easier and more efficient than the manual pliers/solder method. They're not 'perfect' yet - according to the spec I've got a little too much insulation in there - but it's a damn sight neater than my first attempts a couple of years ago :-).
Completed Plug :

Greetings fellow b3tans!

2011-10-21T17:52:00.000+01:00

Amazing! 3-d printing is now officially mainstream - it's appeared in B3TA!

Crimpin' - my style

2011-10-20T21:31:00.001+01:00

I must admit I wasn't that familiar with crimping before starting my RepRap. For the uninitiated, it's the method of attaching the wires to the various plugs to connect to the PCBs. The main connections are the 4-pin stepper motors and the 3-pin headers for the endstops. I also use a 3-pin connector for the thermistor sensor.

The connector consists of some metal pins with tabs, and the tabs are crimped onto the wires. The metal pins then fit into a plastic housing that makes the plug.
My early attempts involved squishing a bare wire between the tabs with some pliers. However, some of my crimped joints were not well attached: sometimes the pins would deform, so they didn't fit into the housing properly, and often the wire would either fall out, or I'd end up breaking some of the wire strands. I usually ended up squishing and then trying to solder them, often also melting the insulation.
This caused a recent problem where my extruder stepper was not moving - I thought it was due to the firmware, but it was actually a failing stepper connection - two of the wires had bad, intermittent connections.

Using my obsession to understand every part of my 'rap, I did some digging. Mr Nophead had an excellent video which solved my immediate problems :-

Looking a little deeper, there are a multitude of articles on the subject : this article on pinball repair has an excellent overview and good advice. The *key* point seems to be using the proper tools. Using the proper crimping tool makes a good crimp joint easy. The Society of Robots tutorial also has a clear guide, and even our own RepRap forum had a useful discussion.

Time to bite the bullet and get a proper tool. Although you can spend over a hundred pounds on a crimping tool, every manufacturer has a slightly different tool, several different sizes and styles, and most are expensive.
After a bit more research, I found that the 'cheap' (<£15) muti-size crimping tools are only useful for automobile connectors (anything with three coloured dots on it - they are too large), 'bootlace ferrules' crimpers are also not suitable (wrong shape), and the telephone/RJ45 crimping tools are special. The 'molex' and other open crimping terminal styles we use are a lot smaller, typically described using wire gauges, e.g. 22-24AWG of 24-28AWG. However, I did find one reasonably cheap well-reviewed tool - the Multicomp HT225D - available from Rapid(£20) and Farnell(£37). The correct tools have a small 'B' shaped indent, which bends the tabs back on themselves to tightly hold the wire. A properly crimped joint does not need soldering and is more than strong enough for RepRapping connections.

Also worth noting is the huge variety of crimping pins, housings, gold/brass/tin platings, and huge number of options when you go looking to buy connectors. Note that certain pins fit certain housings - you need to make sure the pins, housings, sockets all come from the same range - there are a bewildering array - just see the molex site! The two Molex ranges I found most applicable to RepRapping were the KK range (cheap and cheerful, already used for the stepper and range sensors) and the SL range. Both are available in the 2.54mm (0.1 inch) pitch that the RepRap boards use for the endstops and I use for my steppers.
I personally prefer the SL crimping terminals (16-02-0088)- they look like they will connect better (holding from both sides) rather that the KK terminals that push one side against the housing. I also picked up some 3-way and 4-way housings for the terminals. According to the Molex site, they will use the 70058 range of pins, which include the 16-02-0088.
I went for the gold-plated terminals, as the header pins on my boards are already gold-plated, and the gold-plated terminals have a lifetime of 100 cycles (plugging and unplugging) - the tin ones only have 25 cycles. I also wanted some reasonably chunky wire for the steppers, so I got some 4-way 24AWG ribbon cable, which determined the size of the crimp terminals (22-24AWG) I needed.
I also picked up some male pins (16-02-0081) - so I can make some wire-to-wire connectors. Most of my wires have awful twisted and soldered bodges where they're connected together - covered with heatshrink when I remembered to put it on before soldering, and insulation tape when I didn't. I'd like to replace my bodges with proper pluggable connections, particularly with the stepper wires.

I hope this will fix my dodgy connection issues, and also will tidy my 'rap wiring up at the same time.
:-)

One step forward...

2011-09-04T16:42:00.000+01:00

I spent the last couple of days fiddling with software and firmware.
I started with the 'official' RepRap host and firmware, but since I've got a complete mix of electronics (single Arduino mega, self-designed mega shield, separate extruder boards (X,Y, Z, E) and custom heater board), I needed to update all of the pin assignments and configuration files.

I made reasonable progress, managed to get the XYZ axes working fine, but it refused to turn the extruder stepper. I tried various things, ( including heating extruder to 200C), but it refused to move.
I then tried to get the latest host / firmware from git, but while doing this managed to mess up my java3d configuration slightly. Now, all I get is :

DEBUG: Attempting to initialize Arduino/Sanguino [0.174s/87ms]
Exception in thread "J3D-Renderer-1" java.lang.UnsatisfiedLinkError: javax.media.j3d.NativeScreenInfo.openDisplay()J
        at javax.media.j3d.NativeScreenInfo.openDisplay(Native Method)
        at javax.media.j3d.NativeScreenInfo.getStaticDisplay(NativeScreenInfo.java:48)
        at javax.media.j3d.NativeScreenInfo.isGLX13(NativeScreenInfo.java:36)
        at javax.media.j3d.NativeConfigTemplate3D.getBestConfiguration(NativeConfigTemplate3D.java:67)

...

I've tracked this down to a missing j3d*.so file. I have tried a number of things (setting LD_LIBRARY_PATH, java.library.path, putting the .so files in the current directory, etc) but there is also a problem with 64/32bit libraries. Downloading latest versions of the libraries, etc also didn't help :-(. I think it is more subtle than just missing the .so file in the path.

I switched to use replicatorG - nice program - but the 5d firmware still didn't move the extruder (after fixing some baud rate problems).

Finally, I updated to the 'Sprinter' firmware - slightly easier to configure - and this, in conjunction with the ultimaker version of replicatorG, allows me to move the extruder stepper!! woohoo!

Now, to test the heater/extruder, configure the parameters, connect up the axes...

Edit:
Oops. Nothing to do with firmware problems, just some dodgy intermittent connections on my stepper. Unplugging the mega during the firmware 'upgrade' wobbled the wire, making it work the next time...
Nothing to do with the firmware versions!!!

Back on the horse!

2011-08-31T20:12:00.002+01:00

After a long delay, I have finally got back to rewrapping!
I dusted off the darwin, tightened the bolts, and rubbed the rust spots off the rails (stored in the garage - not good!).A couple of the acrylic joints had cracked, and a couple of the cross-bracing rods had come off. I tided and reaffixed as best I can. I spent yesterday and today re-plugging the gen2 stepper driver boards into my gen3/Arduino mega setup, and then fixing the firmware for my custom setup.
While uploading the firmware, I was getting a lot of errors -

Binary sketch size: 28098 bytes (of a 126976 byte maximum)

avrdude: stk500_paged_load(): (a) protocol error, expect=0x14, resp=0xa7
avrdude: stk500_cmd(): programmer is out of sync

Although the upload still *seemed* to work, it was a little worrying. Occasionally, it would work OK, but almost every upload would report this error.
Checking the internet, one post mentioned interrupts causing problems. I know that interrupts are used in the firmware for stepper timing and extruder heater control.I found that if I uploaded the 'blink' sketch first (nice, short quick sketch) and then the firmware, it uploads successfully without any errors!
YMMV :-)

Calibre, and Kindle, and books on the Calibre Webserver

2011-07-31T11:38:00.000+01:00

Sad but true - I spent my friday night fiddling with PCs.

I've got a Kindle - an excellent reader - and a bunch of ebooks I've downloaded from Gutenberg. I already use Calibre to load the ebooks onto the kindle, but I liked the idea of accessing the library over my wifi network. Calibre has a built-in web server, on port 8080. (Also delete the calibre web username/password, and convert all your books to MOBI or LIT formats).

The Kindle browser is flawed though - it only connects over port 80 (HTTP) or 443 (S) :-(

I already had apache running on my main server (Giles) on port 80, so time for some tweaking:

I set up an alias for my server (in /etc/hosts/) :

127.0.0.1 localhost
127.0.1.1 giles

192.168.0.11 calibre.giles.local

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

192.168.0.11 is giles's static IP address. calibre.giles.local is my new virtual server name.

Added an apache conf file to use a virtual host (/etc/apache2/conf.d/calibre.conf):


ProxyPreserveHost On
ProxyPass / http://192.168.0.11:8080/
ProxyPassReverse / http://192.168.0.11:8080/
ServerName calibre.giles.local

This tells apache to route any traffic from calibre.giles.local to the calibre webserver (port 8080).

Now, using a browser on giles, I can see the calibre server by visiting http://calibre.giles.local

This works great, but only when I'm on giles - from any other machine, I would have to edit the 'hosts' file to add the DNS entry - and on the kindle that's not possible.

OK, more tweaking:

Installed dnsmasq (sudo apt-get install dnsmasq). This is a local DNS caching server - it caches the DNS records so it speeds up your browsing (fractionally) but more importantly, it also serves the local /etc/hosts file - so my new calibre.giles.local adress will be served to anyone using this DNS server.
Changed the /etc/resolv.conf:

nameserver 192.168.0.11

i.e. - get giles to use it's own dns server.

Changed /etc/dnsmasq.conf to add :

resolv-file=/etc/resolv2.conf

This avoids dnsmasq using itself to look up entries!

server=194.168.4.100
server=194.168.8.100

These are the two Virgin Media cable DNS servers (my ISP): I could also have used any public DNS servers.

Restarting dnsmasq (service dnsmasq restart) to pick up the changes, I can test this :

dig google.com

gives me 9ms the first time, the 0ms the second - the cache is working.

dig calibre.giles.local

shows 0ms - it is in the hosts file.

So, to make my entire network pick up the new DNS server: Login to my Apple Airport router, and go to IP (Internet) settings. Change the DNS list to have 192.168.0.11 first in the list.

All my other machines on the network use the airport router as the DHCP server and gateway/DNS proxy.

So:
Kindle connects to the wireless network - gets the DHCP address and a DNS server of 192.168.0.1 (the AirPort router).
Go to menu - experimental - web browser and type in "calibre.giles.local".
Kindle asks the airport router DNS for the address.
Airport router DNS asks Giles DNSmasq for the address. Found in local hosts file.

Kindle now displays the calibre web interface. You can search for books/authors, download and read any book (click on the MOBI file) :-)

VNC problems in ubuntu?

2011-07-20T21:54:00.000+01:00

I've been using VNC to remote access my two Ubuntu Natty Narwhal machines, and having terrible trouble - the VNC screen not updating, to controlling properly, etc.

It looks like the 3D and special effects play havoc with the VNC server - not displaying properly, etc.

Try using

gdmsetup

- the 'login settings' manager under the administration menu, or go to the top-right switch icon and and click System Settings, then 'Login Screen'.

Enter your admin password, then select 'Ubuntu Classic (No effects)' as the default session. Reboot or logout/login.

This changes ubuntu to use the standard gnome menubar and disables the 3d and animation effects.
I found that VNC worked much better with the classic menu and desktop effects off :-).

Multiple webcams on ZoneMinder (Part 4)

2011-07-04T20:17:00.000+01:00

Some success!

The USB 3.0 route turns out to be a slight misunderstanding. The key factors involved are :
1) Bandwidth required by each camera, and :
2) Number of USB 2.0 controllers.

It appears that USB 1.1, 2.0, and 3.0 subsystems are basically independent of each other.
A USB 2.0 motherboard has a usb 1.1 and a usb 2.0 controller. The *total* bandwidth for the usb2.0 controller is 480M, and any 2.0 devices share this bandwidth (whichever USB port or hub they are on). USB 1.1 devices similarly share a single 1.1 controller (often labelled a legacy controller).

The usb 3 hub I have seems to have a usb 3.0 hub + a usb 2.0 hub (+ probably a usb 1.1 hub).
Connecting two 2.0 devices (direct, of through the hub) shares the bandwidth of a single 2.0 controller on the USB 3.0 card.

Using the uvcvideo bandwidth quirks mode, I can connect two YUUV webcams to a single usb 2.0 controller - any more fail. This is true whether the port is a standard USB 2.0 hub in a 2.0 motherboard socket, or a USB 3.0 hub in a USB card.

To connect more cameras, add more 2.0 controllers. These can be in a USB 3.0 PCI-e card, or a plain USB 2.0 PCI card, or anything else. Apparently the USB 2.0 controllers included on the usb 3 chips are slightly better as they don't have any other demands on them and only have to deal with the usb 2 traffic.

NOTE : the PS3eye camera has a special 'bayer' mode that uses bandwidth more efficiently - if the driver can handle it. This allows windows users to plug in multiple PS3 eye cameras (see Code Laboratories or iPisoft) I haven't found a similar linux driver yet.

So far, I have been able to display 6 cameras simultaneously -
4 x Cheap USB 2.0 webcams - 640x480 at 25fps - YUYV, PAL
2 x PS3 eye cams - 640x480 at 12fps - YUYV, PAL - some breakup.

I have two cams on a USB 3.0 hub, to a USB 3.0 PCI-E card.
Two cams direct to motherboard controller ports.
Two ps3 eyes on USB 2.0 hub to a USB2.0 PCI controller card.

lsusb -t

davidr@hgwells:~$ lsusb -t
6-1:1.0: No such file or directory
/:  Bus 06.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
    |__ Port 3: Dev 3, If 0, Class=hub, Driver=hub/4p, 480M
        |__ Port 2: Dev 4, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 2: Dev 4, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 4: Dev 5, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 4: Dev 5, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
/:  Bus 05.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/2p, 12M
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/3p, 12M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/8p, 12M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/5p, 480M
    |__ Port 4: Dev 2, If 0, Class=vend., Driver=ov534, 480M
    |__ Port 4: Dev 2, If 1, Class=audio, Driver=snd-usb-audio, 480M
    |__ Port 4: Dev 2, If 2, Class=audio, Driver=snd-usb-audio, 480M
    |__ Port 5: Dev 3, If 0, Class=vend., Driver=ov534, 480M
    |__ Port 5: Dev 3, If 1, Class=audio, Driver=snd-usb-audio, 480M
    |__ Port 5: Dev 3, If 2, Class=audio, Driver=snd-usb-audio, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/8p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/4p, 480M
        |__ Port 1: Dev 3, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 1: Dev 3, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 2: Dev 4, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 2: Dev 4, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 4: Dev 5, If 0, Class=hub, Driver=hub/4p, 12M
            |__ Port 1: Dev 6, If 0, Class=HID, Driver=usbhid, 12M
            |__ Port 1: Dev 6, If 1, Class=HID, Driver=usbhid, 12M
            |__ Port 4: Dev 7, If 0, Class=hub, Driver=hub/4p, 12M
                |__ Port 2: Dev 8, If 0, Class=HID, Driver=usbhid, 12M
                |__ Port 2: Dev 8, If 1, Class=HID, Driver=usbhid, 12M
                |__ Port 3: Dev 9, If 0, Class=HID, Driver=wacom, 1.5M
davidr@hgwells:~$

Multiple webcams on ZoneMinder (part 3)

2011-07-03T16:23:00.004+01:00

Alternative page for ubuntu AMD64 / zoneminder:

Webcam log:

Install zoneminder

davidr@hgwells:~$ sudo apt-get install zoneminder

Follow normal instructions for a zoneminder .deb installation:

sudo ln -s /etc/zm/apache.conf /etc/apache2/conf.d/zoneminder.conf
 sudo apache2ctl restart
 sudo chmod 4755 /usr/bin/zmfix
 zmfix -a
 sudo chown www-data.www-data /usr/share/zoneminder/temp
 sudo vi /etc/sysctl.conf

Add the following lines at the end of the file:

kernel.shmall = 250000000
kernel.shmmax = 250000000

Pick up shared memory changes:

sudo sysctl -p
kernel.shmall = 250000000
kernel.shmmax = 250000000

I have 4 identical cameras plugged in. The order of video0-video3 may change if other cams, etc are added.

davidr@hgwells:~$ ls /dev/video*
/dev/video0  /dev/video1  /dev/video2  /dev/video3

Rather than use the video0 devices, there is a more fixed set of device links in /dev/v4l/by-id and /dev/v4l/by-path.
NOTE: there is a bug in zoneminder that the device name is limited. For some of my cameras, the by-id or by-path was truncated, and zoneminder couldn't find it.

davidr@hgwells:~$ ls /dev/video*
/dev/video0  /dev/video1  /dev/video2  /dev/video3
davidr@hgwells:~$ ls /dev/v4l/by-path/
pci-0000:03:00.0-usb-0:2.1:1.0-video-index0
pci-0000:03:00.0-usb-0:2.2:1.0-video-index0
pci-0000:03:00.0-usb-0:2.3:1.0-video-index0
pci-0000:03:00.0-usb-0:2.4:1.0-video-index0

So, to get around this problem, define my own paths:

davidr@hgwells:~$ sudo mkdir /cam
davidr@hgwells:~$ sudo chmod 777 /cam
davidr@hgwells:~$ cd /cam
davidr@hgwells:/cam$ ln -s /dev/v4l/by-path/pci-0000\:03\:00.0-usb-0\:2.1\:1.0-video-index0 c1
davidr@hgwells:/cam$ ln -s /dev/v4l/by-path/pci-0000\:03\:00.0-usb-0\:2.2\:1.0-video-index0 c2
davidr@hgwells:/cam$ ln -s /dev/v4l/by-path/pci-0000\:03\:00.0-usb-0\:2.3\:1.0-video-index0 c3
davidr@hgwells:/cam$ ln -s /dev/v4l/by-path/pci-0000\:03\:00.0-usb-0\:2.4\:1.0-video-index0 c4
davidr@hgwells:/cam$ ls
c1  c2  c3  c4
davidr@hgwells:/cam$

Use a terminal window with

tail -f /tmp/zmdc.log

to check for any zoneminder problems.
Open firefox to http:\\hgwells.local\zm to get to the web interface.

Add a new monitor. On the source tab, set the source to:
device : /cam/c1
PAL
YUUV
width:320
height:240

I was able to get two cameras up so far: 3 and 4 fail with dmesg :
[ 159.696321] usb 3-2.4: Not enough bandwidth for altsetting 3
[ 172.716216] usb 3-2.3: Not enough bandwidth for new device state.

Good info on USB in linux

* claim for 5 PS3 eye cameras with one USB3.0 card *

Multiple webcams on ZoneMinder

2011-07-03T11:58:00.002+01:00

Part 2:
Continuing the webcam saga (see part 1)

USB 1.1 and USB 2.0
I was incorrect in my earlier post. Modern motherboards usually have two usb controllers: a USB 2.0 controller and a 'legacy' USB 1.1 controller. Devices on each port are automatically switched to the right controller, so the problem of one usb 1 device slowing down the whole usb system does not occur.

I suspect something similar is implemented on most usb hubs - my USB 2.0 hub seems to cope fine with a mix of 1.1 and 2.0 devices.

Due to the wording of the USB 2.0 spec, some USB 1.1 webcams are labelled as USB 2.0 - despite the fact that they only connect at 12Mb (usb1.1). This is the case for two of my older webcams - a Targus and a Creative Live! cam both only connect at 1.1 speeds.

USB 3.0
Although Linux does have support for usb3 cards there is a bug in the current Ubuntu 'Natty Narwhal' kernel that means that USB 3.0 hubs may only be recognised as USB 2.0 hubs - you can see them using

lusub -t

connecting at 480M (usb 2.0).
This post suggested that a later version of the kernel would recognise the usb 3.0 hub properly.
I re-installed with the latest alpha version 11.10 (Oneiric Ocelot) which includes a later kernel. It now recognises the hub as 5000M.

Webcam USB Bandwidth
Some research on webcam USB bandwidth turned up a useful trick. Webcams request a whole load of bandwidth, usually more than they need.
Symptoms were fairly easy to spot: Opening one camera with

xawtv -v 1 -c /dev/video0

and at the same time opening /dev/video1 in another terminal led to

libv4l2: error turning on stream: No space left on device
VIDIOC_STREAMON - Unable to start capture: No space left on device
fps is set to 1/30
libv4l2: error turning on stream: Device or resource busy
VIDIOC_STREAMON - Unable to start capture: Device or resource busy

This post and this post gave me some useful pointers. The uvcvideo kernel module can be set to ignore the requested bandwidth, and to calculate the right bandwidth. Try:

sudo rmmod uvcvideo
sudo modprobe uvcvideo quirks=128

This will be reset every reboot. If this works, create the following file:

sudo vi /etc/modprobe.d/uvcvideo.conf

containing the line:

options uvcvideo quirks=128

My Hardware setup
My new hardware - in case anyone wants to follow in my footsteps:
Transcend PCI Express Interface USB 3.0 Dual Expansion Card

Tsunami SSU34 100mm USB 3.0 4 Ports Hub

Webcam with Microphone for XP Vista PC Laptop MSN Skype

Output from lsusb :

davidr@hgwells:~$ lsusb -t

/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M
    |__ Port 2: Dev 2, If 0, Class=hub, Driver=hub/4p, 5000M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    |__ Port 2: Dev 2, If 0, Class=hub, Driver=hub/4p, 480M
        |__ Port 1: Dev 3, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 1: Dev 3, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 2: Dev 4, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 2: Dev 4, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 3: Dev 5, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 3: Dev 5, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 4: Dev 6, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
        |__ Port 4: Dev 6, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/8p, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/8p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/4p, 480M
        |__ Port 4: Dev 3, If 0, Class=hub, Driver=hub/4p, 12M
            |__ Port 1: Dev 4, If 0, Class=HID, Driver=usbhid, 12M
            |__ Port 1: Dev 4, If 1, Class=HID, Driver=usbhid, 12M
            |__ Port 4: Dev 5, If 0, Class=hub, Driver=hub/4p, 12M
                |__ Port 2: Dev 6, If 0, Class=HID, Driver=usbhid, 12M
                |__ Port 2: Dev 6, If 1, Class=HID, Driver=usbhid, 12M
                |__ Port 3: Dev 7, If 0, Class=HID, Driver=wacom, 1.5M

davidr@hgwells:~$ lsusb

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 003 Device 002: ID 2109:3431  
Bus 004 Device 002: ID 2109:0810  
Bus 001 Device 003: ID 05e3:0604 Genesys Logic, Inc. USB 1.1 Hub
Bus 003 Device 003: ID 090c:937b Feiya Technology Corp. Silicon Motion Camera
Bus 003 Device 004: ID 090c:937b Feiya Technology Corp. Silicon Motion Camera
Bus 003 Device 005: ID 090c:937b Feiya Technology Corp. Silicon Motion Camera
Bus 003 Device 006: ID 090c:937b Feiya Technology Corp. Silicon Motion Camera
Bus 001 Device 004: ID 046d:c049 Logitech, Inc. G5 Laser Mouse
Bus 001 Device 005: ID 05f3:0081 PI Engineering, Inc. Kinesis Integrated Hub
Bus 001 Device 006: ID 05f3:0007 PI Engineering, Inc. Kinesis Advantage PRO MPC/USB Keyboard
Bus 001 Device 007: ID 056a:0013 Wacom Co., Ltd Graphire 3 4x5

Monitoring a 3D Printer

2011-06-26T15:35:00.002+01:00

I have tidied my new workshop and I am starting to play with 3d-printing again.

One of the ideas I've been thinking about for some time is remote monitoring of the printing process. Many prints can take several hours to complete and I don't have enough confidence to leave it alone for that long. Jumping up and down to check it every few minutes would quickly get annoying, so I wanted a way to control and monitor it from a web interface.

My plan is to use a few webcams to provide pictures of the bed, print, and overall mechanics, and an emergency stop button. Looking around, the best solution for webcam streaming on Linux (Ubuntu) is ZoneMinder - it can cope with streaming multiple webcams. I used apt-get to install it and there are some extra configuration required in the documentation. I can also point a couple of cameras out the window as a home-made CCTV/security solution.

After a bit of fiddling, I was able to get streaming webcam from my PS3 eye webcam: but the other three webcams refused to stream. This was a little odd, since I could happily get pictures using cheese, kamino, xawtv, and they all seemed to connect properly as /dev/video devices and appeared as v4l2 (VideoForLinux) devices. All drivers seemed OK and installed.

xawtv -c /dev/video0 -v 1 can provide useful information, such as the supported colour palettes.

Checking the zoneminder logs ( appearing in /tmp):

tail -f /tmp/zmdc.log 

24/06/11 22:14:03.046389 zmdc[2171].INF [Starting pending process, zmc -d /dev/video3]
24/06/11 22:14:03.047635 zmdc[2171].INF ['zmc -d /dev/video0' starting at 11/06/24 22:14:03, pid = 2869]
24/06/11 22:14:06.224901 zmdc[2171].ERR ['zmc -d /dev/video0' exited abnormally, exit status 11]

And I was also getting messages in

dmesg

[ 1929.678445] gspca: bandwidth not wide enough - trying again
[ 2529.745525] ohci_hcd 0000:00:0b.0: leak ed ffff880036a43730 (#85) state 2

Checking the USB devices looked OK:

davidr@hgwells:~$ lsusb 
Bus 002 Device 008: ID 046d:c049 Logitech, Inc. G5 Laser Mouse
Bus 002 Device 007: ID 056a:0013 Wacom Co., Ltd Graphire 3 4x5
Bus 002 Device 006: ID 05f3:0007 PI Engineering, Inc. Kinesis Advantage PRO MPC/USB Keyboard
Bus 002 Device 005: ID 0ac8:307b Z-Star Microelectronics Corp. USB 1.1 Webcam
Bus 002 Device 004: ID 05f3:0081 PI Engineering, Inc. Kinesis Integrated Hub
Bus 002 Device 003: ID 093a:2600 Pixart Imaging, Inc. Typhoon Easycam USB 330K (newer)/Typhoon Easycam USB 2.0 VGA 1.3M/Sansun SN-508
Bus 002 Device 002: ID 041e:4053 Creative Technology, Ltd Live! Cam Video IM
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 006: ID 05ac:1293 Apple, Inc. iPod Touch 2.Gen
Bus 001 Device 002: ID 1415:2000 Nam Tai E&E Products Ltd. or OmniVision Technologies, Inc. Sony Playstation Eye
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
davidr@hgwells:~$

but checking the USB tree shows that the 3 problem devices are only connecting in USB 1.1 (12M), and the one working device at USB 2.0 (480M).

davidr@hgwells:~$ lsusb -t
1-5:3.0: No such file or directory
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/8p, 12M
    |__ Port 2: Dev 2, If 0, Class=vend., Driver=zc3xx, 12M
    |__ Port 4: Dev 4, If 0, Class=hub, Driver=hub/4p, 12M
        |__ Port 2: Dev 6, If 0, Class=HID, Driver=usbhid, 12M
        |__ Port 2: Dev 6, If 1, Class=HID, Driver=usbhid, 12M
        |__ Port 3: Dev 7, If 0, Class=HID, Driver=wacom, 1.5M
        |__ Port 4: Dev 8, If 0, Class=HID, Driver=usbhid, 12M
        |__ Port 4: Dev 8, If 1, Class=HID, Driver=usbhid, 12M
    |__ Port 6: Dev 5, If 0, Class=vend., Driver=zc3xx, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/8p, 480M
    |__ Port 1: Dev 2, If 0, Class=vend., Driver=ov534, 480M
    |__ Port 1: Dev 2, If 1, Class=audio, Driver=snd-usb-audio, 480M
    |__ Port 1: Dev 2, If 2, Class=audio, Driver=snd-usb-audio, 480M
    |__ Port 5: Dev 6, If 0, Class=still, Driver=, 480M
    |__ Port 5: Dev 6, If 1, Class=vend., Driver=usbfs, 480M

Damn. It looks like I forgot the rule about mixing usb 1 and 2 devices - Plugging usb 1 and 2 forces everything on that hub to run as USB 1 (UPDATE : false).

Mixing around the ports, I still had problems. As a better solution, I've ordered a PCI-E USB 3.0 card and usb3 hub. Each port should happily accept a 2.0 webcam, and should have plenty of bandwidth.
I usually use ebuyer.com, but in this case amazon.co.uk were a lot cheaper! (Usb3.0 card for £10 - hub for £20)

UPDATE:
It seems that the other cameras I had were, in fact, usb1.1 - (even though a couple were labelled as USB 2). A later experiment with four identical USB 2.0 cameras had similar results.
The main problem does seem to be the USB bandwidth. Apparently cameras 'reserve' USB bandwidth (sometimes more than they use) and the usb 2.0 480Mb limit quickly gets used up. I'll post again after testing with USB3.0 (5Gb)

Andtec Builders Review

2011-03-31T20:32:00.006+01:00

Recently, we have had our house extended. Since there are lots of people complaining about builders on the internet, I thought I would redress the balance by posting a review of a positive experience we've had with Andtec Builders.

After

Before

Andy (Owner of Andtec Builders) was recommended to us by a family friend. We had some plans drawn up by an architect, and we got three builders including Andtec to quote.

Andtec quoted the lowest price: but they had several jobs on, and we'd have to wait several months until they were free. One builder was slightly more expensive (within a few percent) but available now: and one quote was significantly over (40% higher).

We decided to wait for Andy based on the recommendations.

A few weeks before, we met with Andy and talked through the project. Andy had experience with the local area and identified a problem with the foundations specified : our house was built on 'made up' ground and they'd have to dig down a long way to lay the foundations on the 'real' ground level (as specified in the building regs). The original architect was unable to make the changes to the plans but Andy confirmed the problem and found an architect that was able to design a floating raft foundation - a reinforced concrete slab that would do the job.

The original estimate for the work was about 3.5 months : Starting mid november, should have the external walls complete by Xmas, roof on by end Jan, internals done by end Feb.

The existing garage disappeared very quickly and work on the foundations went well - it was a bit muddy during the excavations but was a lot better once the concrete slab had been poured. Although the work was in front of the door, Andy made sure we had safe access to the house and worked around our many comings and goings :-).

Work on the external walls was delayed a little by extreme weather - during December, we had a very cold snap (-15C at times) and they went to some lengths to keep working - gas heaters, insulation shelters and tarpaulins to try and warm the bricks so that the mortar could set properly without freezing. I know it was cold - we handed out hot tea, and when we collected the mugs a couple of hours later, one was half-full of solid ice! They valiantly worked through the freezing weather - Andy, Jez (the brickie) and George (labourer) only stopped working the week before christmas, where the snow was a few inches deep and couldn't be melted by the salt. In total, several days were lost due to the weather.

January went well - the floors and roofing went on and a few days into February the roofing was done and the scaffolding was coming down. Once the structure was secure, the work knocking through into the main house began.

We had three walls removed, with steel beams inserted, and an extra door through into the hall. This is the most intrusive part of the build : for the first couple of months, most of the work was outside, and didn't really impact on our daily life. My wife is not well, and is at home all the time. Andy went to some effort to try and organise and schedule jobs to minimise the impact on the household, including leaving the kitchen working as long as possible. Luckily, the new kitchen was in part of the new extension, so Andy was able to put in the new kitchen before ripping out the old one, making the transition much easier than it otherwise might be.
This part of the build also went well - although it's inevitably a bit dusty :-).

Plastering and finishing was good - we asked Andy to do several extra jobs, which he quoted for and added to the scheduled monthly bills. We asked him to plaster the old kitchen ceiling and replace several internal doors, and to lay a wooden floor throughout the downstairs.

All in all, we were very pleased with Andtec builders and their work. Andy and all the staff were polite and professional at all times, and Andy was always happy to discuss and answer questions about any part of the work.

The estimates and scheduling of the job was excellent : Despite the slippage due to the weather, the work was completed according to the early schedule. The additions to the work (installing a new kitchen, flooring, and extra internal work) all went according to estimates.

Professionalism was excellent : They turned up at 8am every day and worked until 4pm. When they were unable to work (due to the snow) we were informed by phone. Because there was a lot of work, if a particular job could not be done (for example due to tiles not arriving) they continued with other work and rescheduled around problems. Someone else commented that they were very tidy - although it was a building site (literally) it was organised well.
All building regulations, inspections, and certificates (gas, electric work, etc) were all present and correct. Estimates, contracts, changes to the contracts and scheduled bills were printed and very clear and supplied on time, so we always knew what was asked for and how much it would cost.

Andy was polite and helpful at all times. Several times specific decisions had to be made (Front door style, positions of sockets, tiles) and Andy gave us options and time to allow considered decisions before ordering or installing.

Along with the building crew, Andy often brought 'Badge' with him. Badger is a lovely border collie, well trained, smart and very friendly. Badge was quite at ease with all the heavy machinery, and would only come in when invited, and didn't jump up or bother anyone - very well behaved. He even made friends with one of our cats (the other two kept well away!).

I would happily recommend AndTec builders to anyone in or around Bath, Frome and Trowbridge.

Thanks, Andy.

Lots of photos of the build in-progress on my flickr feed.

Sentries report bearings to the south west. Thousands of them.

2010-07-13T12:37:00.003+01:00

Well, 53 to be exact.

I've been looking around to collect Mendel parts for a little while, intending to reproduce from my BfB Darwin. I've picked up four nema17 steppers, built myself some stepper drivers and electronics, and I'm now looking for the mechanical parts. On the parts lists are a significant number of bearings, which can be quite pricey.
Luckily, I found RepRapKit.com, based in the UK, and ordered myself a complete set of bearings for less than 20 quid - much cheaper than everywhere else I've looked so far. Excellent service - I had a couple of emails with him and he seems like a really nice friendly chap. Parts were ordered and dispatched quickly, and delivered next day. I got 51 smaller bearings and two M8/skate bearings (including enough to make a geared/stepper extruder), they all look good and turn well. The store is selling ABS and bearings so far, and is looking to expand into extruders and other RepRap bits.

I also got round to blowing the dust off my BfB Darwin. It needs several bolts tightening and some general maintenance, and I disassembled the three stepper motors, covered them in plastic bags and tape, and ground out some proper flattened shafts using my dremmel. Note : metal filings from filing or grinding are not good inside a precision engineered bearing, and since they're highly magnetic, it does tend to attract the dust.

Make sure the bearings and motors are nicely covered (with blutack/tape/plastic bags) otherwise the dirty bearings will seize or grind away very quickly.

I'd had a go at filing the shafts back during the initial assembly, but didn't have the right tools - I did have a few problems with the axes slipping at times. Once it's all back together, it should be fine this time.

Heater board complete

2010-06-25T21:48:00.005+01:00

I've completed and soldered my heater board.

There are 8 PWM outputs from my reprap shield which are boosted using 54A MOSFETS. These should happily drive my extruder heater, heated bed, fans, extra motors, whatever.

I've posted the files to thingiverse. I've also added my single-sided stepper driver files to a thing as well.

I now have four working stepper drivers, one mega shield, and a completed heater PWM board. Only a couple of thermistor sensors, and I'll have a complete set of electronics for a mendel :-)

RepRap host software on Mac

2010-06-19T22:30:00.006+01:00

Just a quick note to anyone trying to get the RepRap host software to run on a new Mac (Mac OSX 10.6.3).

I downloaded the software from the wiki and unzipped it.

To get it to work, I had some problems trying to make it accept a classpath. Eventually I did the following:

Make a directory ~/Library/Java/Extensions

Copy any files with *.jar and *.jnilib extensions to that directory.

The librxtxSerial.jnilib file supplied in the reprap software didn't seem to work. I found one at
http://iharder.sourceforge.net/current/java/ and I replaced it with this newer one.

Go to the reprap host software directory in a terminal window (you need to be in a directory with the rr-logo-green-url.png file in it).

type 'java org.reprap.Main'

This brings up the main reprap windows on my mac, and I was able to load and slice a .stl file. YMMV :-)

UPDATE:
As pointed out by Tony, this is not the most elegant solution. It doesn't help that I was looking at the 'mac-experimental' version from last year, rather that re-building from source :-( oops.

I also found out why I was having problems with the classpath :

java org.reprap.Main -cp $CLASSPATH

is NOT equivalent to

java -cp $CLASSPATH  org.reprap.Main

Doh!
This is usually true of any other command-line program, but any arguments AFTER the classname are passed to the class Main() method. I blame late-night programming :-)
Ignore all the java/extension rubbish, just use instructions from
http://tonybuser.com/reprap-host-on-osx-snow-leopard

A command line that also works is

 java -cp "*" org.reprap.Main

First Thingiverse submission!

2010-06-09T06:45:00.002+01:00

Rather than try and re-create thingiverse manually , I posted my RepRap Mega Shield to Thingiverse.

Renoir's RepRap Arduino Mega shield

Enjoy!

Apple service and board PDFs

2010-06-07T20:36:00.002+01:00

A few weeks ago, I bought myself an Apple MacBook Pro :-) and I've been really happy with it. However, a few days ago, I had terrible trouble trying to load the Ardunio software - segment faults and Kernel Panics (serious errors!) all over the place.

After a bit of debugging, I tracked it down to a single command - 'java -d32' which would cause a segmentation fault or bus error straightaway. A bit more investigation led me to the Apple Hardware test - which reported a 4MEM error, indicating a bad stick of ram :-(.

I dropped into the apple store today, expecting a delay as they had to send my nice new MacBook off, or at least swop out the ram. The apple 'Genius' was very helpful, and confirmed the bad ram - or possibly a logic board - and went off to speak to the manager.

However, 10/10 for service - despite the fact that I'd been using it for 6 weeks, they arranged a swop for a brand new machine right away! They even copied everything over to the new machine! I picked up my 'new' pc, opened the lid and everything was exactly as it had been on the old machine. I am now a very happy Mac customer :-) - that is an excellent example of customer service.

Also produced some PDF files for the Mega shield - available with the eagle files on the
Eagle files for Renoir's RepRap Mega Shield Page.

Renoir's Mega Shield built

2010-06-04T18:42:00.004+01:00

I've been soldering and building and I've finished my mega shield!

From RenoirsMegaShield

The build went well. I 'tinned' the copper pads (using some plumbing flux and a tiny bit of solder), which made the soldering a bit easier. Using a tip (from ladyada?) I converted some standard header pins to some through-pins by pushing them through using the flat on a pair of pliers, three or 4 at a time:

From RenoirsMegaShield

Once I'd fixed the pins, I could put them through into the arduino and check the alignment - OK. I left the pins partially pushed in to maintain the position, and soldered a single pin from each row:

From RenoirsMegaShield

This held them in place when I removed the mega and soldered the rest.

From RenoirsMegaShield

I've now got 10-pin IDC headers for X,Y,Z, and extruder (A) - and a spare (B) using header pins as I ran out of sockets. There's a space for the 20-pin interface connector from the generation 4 designs, and a whole set of +5v/GND/analog in headers for temperature probes, extra sensors, etc. Along the top is an I2C 4-pin header, and similar +5v/GND/digital I/O headers for servos, TX/RX comms, and some PWM pins. 8 PWM outputs are taken to a separate 10-pin IDC header that is intended to go to a MOSFET power driver board to drive the heater and heated bed (coming soon).

Mega RepRap sheild

2010-05-31T21:39:00.004+01:00

I've been working for a couple of weeks on a RepRap Arduino Mega shield. I've got a mix of early generation 2 electronics, a few home-made single sided generation 3 stepper boards, and old arduino with a screw-terminal shield and a brand-new arduino mega.

I designed myself a version of an arduino mega shield to connect the gen3 stepper boards using the 10-pin IDC cables, and it might be useful for anyone transitioning between generations of electronics. Headlines:

Single-sided for home-made boards
5 stepper driver headers - x,y,z,a,b - should match existing gen3 electronics.
(future-proof?) UI interface header that *should* match gen4 electronics.
Heater 10-pin IDC (to plug in MOSFET driver board later) - should be able to drive a reprap setup with 1 or 2 extruders/ heated bed without an additional extruder board.
I2c header as per standard boards
Optional extra 3-pin headers for digital in\out and analog in : +5v, GND, and data pin. This makes it easy to add temperature sensors, kill switches, extra limit switches, etc (I'm only using the min endstops).

If you think it might be useful, the files are here :
Eagle files for Renoir's RepRap Mega Shield

I've just etched one using my laserprinter/laminator method, and I've just etched two more single-sided stepper drivers. I'll post some photos once it's been assembled.

p.s. All files (and anything on this blog) available under creative commons attribution 3.0 licence.
:-)

Useful PCB notes

2010-05-17T19:15:00.002+01:00

http://www.electricstuff.co.uk/pcbs.html

Nice clear semi-pro PCB instructions :-)

Useful suggestions for PCB-making services

Home-made Steampunk cogs

2010-05-04T19:31:00.008+01:00

I like the steampunk look, and my daughter and I fancy building a steampunk keyboard.
Alongside my PCB building, I tried building some steampunk-style cogs to use as decoration or parts. I found some thin copper foil (0.1mm) from a sculptor's and restoration supplier Tiranti.

From Steampunk cogs

It's nice stuff, thin enough to cut with scissors, but thick enough to cover corners and bend around shapes without ripping. It should cover keyboard edges well.

One of the things I wanted to try was to use PCB etching techniques to make complex cogs or clockwork shapes. I put together a couple of templates (see the end of this post) and tried a few things to transfer the toner onto the foil - the best technique ended up being the label backing paper as per PCBs. Because you need to cover both sides, I mirrored the label and folded it in half - then placed the copper foil inside the transfer.

From Steampunk cogs

A couple of passes through the laminator, and the toner is fused onto the copper. I also printed a more complex mechanism onto normal PCB board.

From Steampunk cogs

I then used standard ferric chloride (PCB etching fluid) to etch the copper. You can either dunk the boards and gently stir the etchant, or (with GLOVES) rub it on the board with cotton wool or a kitchen towel.
Etching the PCB was pretty quick: etching the foil all the way through took a about twice as long as the PCB board. The etching worked well, most of the complex detail and cog teeth coming out well.
However, the toner is much more difficult to remove. With the PCB, the board gives the copper plenty of strength so the toner can be scrubbed away. With the foil cogs, they tear easily, so you can't scrub them. I tried soaking in acetone (nail varnish remover) and this removed some, but not all the toner. An agitated acetone bath (maybe an ultrasonic jewellery cleaner?) might remove more.

From Steampunk cogs

The normal PCB came out very well. The detail is good and the board can be scrubbed to remove all the black toner.

From Steampunk cogs

One of my ideas was to place some LEDs behind the PCB to shine through the board, illuminating the hidden pattern: this backlighting does give a really nice effect (shown against a normal lamp).

From Steampunk cogs

A nice large panel with plenty of clockwork mechanisms would look good instead of a numeric keypad, or as a lit panel in a PC case. Layers could even be stacked for a greater 3-d effect. This is just the research so far, I'll post more as it proceeds.

How to make a gear template (examples)

Generate a gear at woodgears.ca - I used tooth spacing 6mm, gear 1 teeth 100, spokes 5 and show spokes on.
Hit the 'print' button, then OK. My mac then allowed me (bottom left PDF dropdown) to import the PDF into iPhoto, basically exporting it to a jpg.
Edit the picture in Gimp. I did the following operations:
1. Fill the outline with black
2. Use Select - by color and then click on the background (white)
3. Use Select - shrink to shrink the selection by 20 pixels (not from the image border)
4. Use Edit - Fill with FG colour to fill it with black
5. Use Select - all and Edit - copy
6. Use Image - Canvas Size. Click the 'link' between the width and height to unlink them. Double the height and add two pixels.
7. Click Image - transform - flip vertically
8. Click edit - paste as - new layer. This should give you a mirrored image top and bottom, with a small line between them.
9. Click file - save and export when prompted.
Laserprint onto label backing paper, heat transfer to copper foil, and etch.

Mendel home-made stepper boards

2010-05-04T19:10:00.005+01:00

A productive weekend: I used the laserprinter technique to make four more single-sided stepper drivers.
I experimented with plain paper, baking paper, greaseproof paper, oiled paper, but the best transfers were with my cheap label backing paper.
To economise on the amount of label paper, I cut a section roughly a bit larger than the PCB, and stuck it to a clean A4 sheet with some of the discarded stickers. This then goes through the laserprinter.

From StepperPCBs

I then took off this section, bent it over the PCB and taped it down, then ran it through my laminator a couple of times. This transferred the toner to the PCB.

From StepperPCBs

After etching, I had four new stepper boards to build

From StepperPCBs

Cats and chips

2010-04-28T19:33:00.008+01:00

Seeing as I've seen a few other RepRappers with cats, I thought I'd introduce mine to the internet:
We started with Jess, who's now a bit old and grumpy, mainly because of the two newbies.

From Cats

Recently, we've given a home to two more kittens from the rescue home, two brothers, Harry and Oscar. Here's Jess and Harry:

From Cats

And here's Oscar - who appears to be made of rubber :-)

From Cats

With three cats, we go through a lot of catfood. In fact, we were going through 3 pouches morning and evening + two big bowls of dry food. However, after a while we found that it wasn't just down to ours. Jess is very nervous, and runs rather than confront other cats, and Oscar and Harry are very friendly, which even extends to other cats in the area. Several evenings we saw other neighbourhood cats wandering into our house - we even ended up naming them. FatCat was a big tomcat, who could barely fit through the flap: GreyCat was an adult long-haired grey, and black kitten frequently comes to play with Oscar and Harry in the garden. Most mornings, as I came down, the catflap would bang as someone left and all the foodbowls would be empty.

So, what's a computer nerd to do? As usual, I found a high-tech solution. PetPorte make a cat-flap that has a built-in chip reader, so it can identify your cats and open the door for them, while keeping the others out. Oscar and Harry were already chipped (Neutering and chipping is part of the rescue deal), and Jess got chipped at the local vets for £30, since it's a good idea anyway. Chipping is a tiny RFID tag injected into the back of the neck - the ID number is linked to a database with your name and address if your cat ever gets lost.

The catflap looks pretty normal - it's just got a covered 'porch' on the outside, containing a coil to read the RFID tags. Pics: Inside is pretty normal, just a small mains wire to the plug.

From Cats

Cat's eye view from outside - you can see the coil in the porch used to read the tags.

From Cats

Once an authorised cat goes under the reader, the flap unlocks for a few seconds, so it can come in, then re-locks (out only) so others can't follow it. There's also some extra features if you want, like a light sensor that doesn't allow them out after dark, and 'vet mode' - i.e. in only. It runs off a standard mains plug and/or a 9v pp3 battery backup.
It's a bit expensive, compared to other systems (like magnetic collars, etc) but it does exactly what it says on the tin. It will read our cats as soon as they're under the reader, and all three have been using it successfully for the last several days. It's well suited to Oscar, as he's lost four collars in the last three months - he tends to leave then in trees while climbing. You do have to 'scan' your cats the first time - it has a learning mode (half a minute to scan a new RFID tag) for each one. Both Harry and Oscar were so interested while I was installing it, they were picked up straightaway. Jess hisses when I pick her up, but it only took a second to scan her, then she stalked off in disgust.

It's been working perfectly so far - none of the intruders have been in, and the food bill has been cut by about half, plus Jess is a bit happier now the other cats are confined to the outside.

Pretty successful so far - I wonder if they do a human version? Children do lose keys so often... :-)

UPDATE:
Catflap in action: Black kitten has just tried to follow Harry in, but isn't allowed:

From Cats

Recycled Heated Bed

2010-03-28T21:17:00.002+01:00

I finally put together an idea that I've had floating around for a while.
My wife had an old heated pad where the fabric had worn through. I took out the plug and element, and saved it, because I though it probably had some nichrome wire in the element.
Fast forward several months, to all this recent talk of headed beds.
I uncovered the element from my 'parts' box, and inspected it - the insulation is all intact, all well covered, no damage and safe. A careful test showed it still warmed up when plugged in.
I grabbed a couple of steel baking trays from Wilkinsons (£1 each) and my kapton tape.

From HeatedBed

I punched a hole in one of the trays, carefully bending the edges and masking them with tape so there were no sharp edges. I could then feed the element through and taped it to the back of the tray in a rough spiral with the kapton tape.

From HeatedBed

The other tray, I covered the base with strips of kapton tape, and placed over the element tray. VERY IMPORTANT: I added an earth wire grounding both of the trays to mains earth (the PSU case).

From HeatedBed

Hey presto, heated bed.

Firing it up, it reached 80C+ in a couple of minutes on 'full'. I haven't run it further than that without mounting it properly first.

Potential problems:

Using Mains electricity - you need to be *very* careful and earth the case. Check your safety three times.
I don't know what temperature it will reach: it needs to be mounted properly and tested. Temperature control is provided by the original power box - I can have 1, 2, or 3 and it will automatically switch off after 90 mins. (probably not a problem unless I'm doing a long print).
The surfaces of the tins are relatively thin pressed steel. I suspect they're flat enough for 'small' prints (up to makerbot size) - I'll have to see if they're flat/rigid enough for larger objects.

Potential improvements:

I could fill the thin gap between the element and the two plates with fire cement: it might improve heat conduction and possible help with stiffness/flatness.

SMD - it ain't so hard!

2010-03-22T21:27:00.002Z

I soldered my first surface mount board successfully! It was a lot easier than I expected...
I thought I'd write up my novice guide to SMD soldering, so any other novices have the confidence to get started.

Step 1 - get organised
I found a beading box from the local market stitching/craft stall had plenty of small boxes for my smd components. I labelled the blank strips as I took them out of the labelled bags, marking the component values several times along their length, because if they get mixed up the numbers are too small to read without a magnifying glass. Sort out and safely store the components. I marked each box with the value and the component number (R3, C4, etc) using post-its.

From SMD_stepper

Clean and scrub the circuit boards, so the copper is perfectly clean and ready to accept the solder. I used a trusty green scourer and Cif cleaner(light abrasive).
I also used the laserprinter method to print the silkscreen layer to make it easier to place the components.

From SMD_stepper

Step 2 - Working space and tools
Sort out a working space. I used several sheets of A4 paper taped together, because components show up well against them.

From SMD_stepper

While placing, I needed some kitchen/loo roll to wipe the solder paste off tools. I also used:

From SMD_stepper

Solder paste, a couple of pairs of tweezers (the curved point ones are best), and a sharp knife. Printout a large copy of the PCB diagram with the component layout, and a separate list of the component values and numbers. It's much easier to double check before you solder, not after.

From SMD_stepper

A magnifying glass is essential. Luckily, my wife had a nice big glass on a flexible mount for her cross-stich, so I could borrow that.

Step 3 - Solder paste
Add a tiny amount of solder paste to each pad. I went with the absolute minimum, thinking it wuould be easier to add more later than remove it - but it was more than enough. I ended up using the point of the tweezers and the point of the knife to move extra paste from pad to pad. For the IC, I spread a line of paste all along the pins, and then used the blade to split each individual pads apart, cutting a gap between individual pads.

Step 4 - Place Components
Gently peel apart the film from the carrier, and tap the components onto the paper. Using the tweezers, place the components onto the pasted pads. Check and double-check the values or labels, and check the diagram to make sure of the positioning. Getting perfect alignment is not essential, but make sure the electrical contacts will be correct.

Step 5 - Apply heat
Lots of internet advice talks about temperature controlled ovens, customized hotplates, etc. I haven't got any of that, so I whacked it on my electric cooker ring.

From SMD_stepper

I'm not recommending this, although it worked for me (although I seem to have cooked a couple of green LEDs). The solder paste starts off a murky grey but when the solder hits temperature, it suddenly becomes a nice shiny solder joint and pulls the components into place.
I put the board on a cold cooker ring, turned it to 6 (full) and watched it. Once the joints popped, I quickly checked them (one corner was slightly raised, pressing it down with the tweezers popped the last few joints) and when they were all done, turned it off. After it had cooled enough to touch, I moved it and let it cool completely.

Inspection photos:

From SMD_stepper

Step 6 - Remaining through-hole components
I soldered the remaining through-hole components (mainly connectors) and added some wire bridges, because I only have a single sided board. This is also why the SMD components are on the bottom and the through-hole are on top.

From SMD_stepper

A couple of the green LEDs don't work, and the 4-pin connectors I have are the wrong size, and the 10-pin IDC connector has ended up reversed, but I wired it up to an arduino and a NEMA-17 stepper and it runs the stepper fine. All in all, a good experiment.

I'll fix the board and run off a few more for my Mendel - I've got enough components for four more stepper boards. Single-sided eagle files are available and are based on the stepper driver 2.3 from MakerBot.

UK Suppliers

2010-03-18T17:29:00.006Z

Recently, I've come across a couple of parts that might be useful to UK RepRappers.

I found a stepper driver board from DIY CNC

It's based on the A3977 stepper driver chip, like the version 3 of the RepRap stepper driver board. It has handy dipswitches to select down to 1/8 stepping, and handles up to 2.5 amps. There are screw terminals for the connections and an optional edge connector. Although the recommended voltage is 24v+, I've contacted the chap, and he says it should work down to 10v - and the board design seems pretty similar to the 12v RepRap boards. One board is £27 but there's a discount for buying 3 or 4 for a Mendel. Certainly worth a look as an alternative to a polulu-type board imported from the states, if MakerBot is out of stock.

I've just finished building a single-sided SMD version of the 2.3 stepper driver, and I've got the parts for a few more, so I haven't tried these personally.

On the other hand, I did buy an Arduino mega for £25 from D-Robotics from an Ebay auction. Arrived after a couple of days, seems to be a 'clone' of the reference design from a hong kong/chinese company.

From SMD_stepper

Plugged in, recognized as an arduino mega, example sketch loaded straight off.

Should be a good upgrade from my Gen2 (arduino) electronics: I should be able to load in the 5D firmware, unplug my breakout shield from the arduino and plug in the Mega!

Arduino Mega Shield

2010-03-16T10:00:00.004Z

I'm fiddling with an eagle design for a RepRap arduino mega shield. I couldn't find any eagle files for the basic sheild pins, so here's one I ripped from the arduino reference design.

Arduino Mega Shield Eagle Files

Schoolboy Error

2010-02-28T22:25:00.004Z

In my last two boards, I made a schoolboy error:
Both boards (due to different reasons) ended up being reversed left-to-right.
Now, during the transfer from paper to the board, it does mirror/reverse the image. I had 'overcompensated' and flipped the board twice, i.e. the wrong way.

Also, the stepper driver experiment was for the brand new 3.0 version, not the tried and tested 2.3 version (as noticed in the comments).

I've knocked together a version of a single sided board for the stepper driver v2.3 here - you want the v2 for the 2.3 board (eagle and .brd files provided). I dropped the ethernet connections (too many holes) and reverted back to the RepRap 3-pin connectors for the max/min endstops.

Here's a couple of etched boards, using the laserprinter/laminator/dab etching method:

From PCB

I had to tidy a couple of edge tracks with a CD pen, but they came out well.

Here's my temperature controller (0-100 degrees C, controlling a relay) for another project:

From PCB

I bought some more copper board today from Maplins, so I should be able to make them a bit larger next time and avoid the issues with the transfer at the edge of the board.
Now to drilling several hundred holes with my new dremmel...

Etched boards

2010-02-20T20:12:00.006Z

Here's the two boards I etched using the laserprinter/laminator method.

From PCB

The laminator bound the laser toner to the boards really well. I used a few mm of ferric chloride, and dabbed/rubbed it onto the board with a cotton wool ball (wearing GLOVES). The centre etched first, and I was able to rub more around the edges to finish off the etch.

The etching worked really well. The detail came out fantastically - even the drill marks came out on the stepper board. You can also clearly see a minature mouse pointer in the centre of the temperature board - oops!

The toner bound so well to the copper that I had to scrub the completed boards with a green scourer and cif to get the toner off - it was harder work than cleaning the boards in the first place!
There is a small error on the stepper board (bottom left corner, just above the resistors). When transferring the laserprint to the board, before the laminator, I accidentally smudged a track. This is probably repairable when I add the via/wire bridges.

[Edit - I thought this was based on the Makerbot stepper driver (A3982) - but I actually picked up the files from the RepRap distribution, which are actually V3.0 of the stepper driver, based on the A3977. Wow, I'm ahead of the curve!]
Schematic:

From PCB

Ah! That's the way to do it!

2010-02-19T12:52:00.004Z

Last night, I got round to making a couple of PCBs with the LaserPrinter method, using a couple of tips scavenged off the comments and interweb.

From PCB

I printed onto some sticker backing paper from some laserprinter address labels I had around. The first sheet, which was completely sticker-free, was a bit thin and bendy and got jammed up in the rollers and didn't print properly. After retrieving the sheet (and extracting a cat toy from the inside of my LaserPrinter), I removed a few stickers from the centre of a new sheet of stickers, so it was thicker and stiffer.
This printed perfectly.

I then taped on my cleaned copper board (Cif and green scourer again) and put it through a cheap home laminator machine.

This worked really really well. The toner transferred perfectly to the copper, and the sticker paper was left completely clean. It seems to have bonded well to the copper, so I will have a go at etching the boards soon.

From PCB

I re-printed my temperature controller PCB board. Since I only had a PDF of the circuit diagram, I had to mirror it before printing. Last time, I used a command-line utility and a converter - but this converted the tracks into a low-res jpg, which worked but was certainly not the best quality.
This time, I printed out the PDF version and measured the printed PCB (49mm). I then zoomed in, so the tracks were filling the whole screen (in the PDF reader) and took a screenshot. This screenshot can be cropped to the edge marks, and flipped in GIMP, and GIMP offers specific print options to print out at exact sizes - i.e. the size measured earlier. This worked well (apart from a minature mouse pointer appearing on my PCB tracks!)

Single Sided Makerbot Stepper Driver board

From PCB

I've been trying to get hold of the Stepper driver board for a little while, but while waiting I thought I'd try and make a single-sided version of the PCB that was easier to etch at home.
First task was getting to grips with Eagle, and downloading the .brd files from the RepRap repository. The biggest problem with the mix of through hole and surface mount components is that the pads end up on both sides of the board - the through hole pads are on the bottom, and surface mount on the top.
I loaded up Eagle and mirrored the through hole components onto the other side of the board. The plugs are now pointing downwards (not ideal) but at least the pads are now on the top side. Rotating the connectors by 180 degrees helped match the tracks to the existing routes.
This left lots of messy tracks on the board, but a bit of work tidied them up. I then went to work moving via's (that would now have to be wire links) and moving the via points so they are not underneath the surface mount components, as I'd have to through-hole solder them. I'm no circuit board designer, so I went with moving the components as little as possible, and re-routed the tracks to avoid or shorten the vias where I could. Straightening the vias helped avoid crossing wires, and some of the connectors could be connected directly.

I printed off the PCB and transferred it to the copper. If it etches well, and I can drill some holes without ripping all of the tiny tracks off the board, it might be worth getting some components to build up a version.

[Edit - here are the eagle board files for anyone who's interested. Probably there will be later versions that might actually work.]

New toys - baby steppers!

2010-02-11T21:58:00.006Z

Kickstarting my RepRap project again, I splashed out on four NEMA 17 stepper motors from Zapp Automation - four SY42STH47-1684B motors. Good service, arrived quickly and well packed.

I needed a stepper for an extruder, so I got 4 to give an easy upgrade path to a mendel.

I'm currently running on generation 2 electronics, so I also need another stepper driver. The gen3 boards are great, but they are out of stock at the moment, and because they're fully populated, they would replace my current setup - not a problem, but an expensive upgrade.

While looking around, I found a couple of other posts on this subject:

Casainho also grabbed one of these motors and is looking at driving it with a Pololu Stepper driver board.

Bothacker posted about his electronics setup which uses Sparkfun driver boardscontrolled by a Seeduino Mega.

I really like BotHacker's approach. It's modular, so it's easier to upgrade and slightly more flexible for re-use on other projects, and the seeduino/arduino split for extruder heads can be skipped to start with (as most only have one working extruder) and added later if required. It woul probably be more expensive overall, but is probably more readily available - the driver boards are replacable by other manufacturers, other mega/seeduino controllers can be plugged in. The connector boards are easier to design and manufacture at home, reducing the bottleneck of available boards.

I'm currently leaning towards BotHacker's approach.

RepRap - As Seen On TV!

2010-02-05T13:28:00.001Z

RepRap / RapMan was mentioned on Points West yesterday...

Nice TV spot advertising!

Home-made (bodged) PCBs!

2010-01-06T18:15:00.009Z

For a little while now, I've been interested in trying to make my own PCBs using the laserprinter method discussed on MAKE. I finally got around to trying the method today, and I'm really impressed with the results! For my first attempt, it worked well.

I needed a temperature controlled waterbath for a separate project, and I found a suitable circuit on the internet, courtesy of a Make article.
Instructions and comments below:

It had a PCB diagram, so I didn't need to mess about with designing my own.
Print out the PCB diagram, at the correct size, mirrored, then use it to cut a copper PCB to the right size. For my first attempt, I made a couple.Make it as dark (as much toner) as you can.

From PCB

Clean the surface of the copper as well as you can. Any grease stops the toner sticking. I used a green scourer and some 'Cif'.

From PCB

Take your dark laserprinted PCBs, and tape the copper side of the PCBs to the stencil.

From PCB

I then ironed the back of paper (setting on 3 dots), letting the heat soak into the copper. The heat causes the toner to melt and to stick to the copper. Spraying water on the back of the paper, you can see the toner stuck to the copper:

From PCB

Using water and rubbing, most of the paper can be removed, leaving the toner on the PCB. It seemed to be pretty well stuck on, and only a couple of little gaps.

From PCB

When you've got the paper off you can see the layout on the copper board. Any gaps or tidying up can be done with a sharpie marker - apparently they are also etch-resistant, like the toner.

From PCB

Now, it's time for the etching. I got a standard bottle of etching solution from Maplins. Note that this can be messy and this stuff is nasty chemicals - treat with care. It will stain pretty much anything it comes into contact with (including stainless steel sinks!). Wear rubber gloves and take care.
I poured some into an old plastic container, and used a soaked tissue to dab and rub it onto the board. The toner works pretty well as a stencil, resisting the etching - and dabbing it by hand allows you to pay extra attention to the edges or places where it needs more.
No pictures, I'm afraid, as my hands were all dirty.
After a few minutes, it's fairly obvious when the copper is etched away. I was able to rub over a few areas that weren't quite done yet to finish it off, then I dunked them in a big bucket of water to clean them up.
The black toner can then be scrubbed off using a green scourer, leaving a completed board:

From PCB

This left a pretty good result. It still needs drilling (a chance to use my new Dremmel! Yay!) and a little repair where the toner didn't stick, but I'm pleased with the first attempt.

This technique looks suitable for the few 'one-off' boards for specific projects now and again.

The final result:

From PCB

Open-Source to the rescue!

2009-10-13T20:41:00.006+01:00

To build anything in a RepRap, you need to have a 3-D design, save it as a STL or triangle mesh file, and load it into the RepRap host software (or skeinforge).

To create these designs, RepRappers use different programs - Either an adapted 3-d modelling programs, originally used for animation (like Blender and Art of Illusion), or freeware versions of CAD software (like CoCreate). These solutions work, and work well, but each program has seperate advantages. I've been looking out for a 'better fit' - a CAD-style program, that supports building meshes and solids.

Make magazine today furnished me with a link to FreeCAD.

It's pretty slick - either I'm quite lucky, or it works quite well. Within a few minutes I was able to load it up, get started, create a small cube model, export it to an STL file and import it successfully into the RepRap Host software (not always an easy thing!).

OK, lets give it a real test...

Let's load up some data from a complex file: a human head.
To really test it, I created a large sphere, stuck it on top, and did a 'union' (Join).
This is not nice: most complex geometries cause all sorts of bent and broken and backwards triangles. Lucky there is an analysis tool to point all this out:

From FreeCAD

Pressing some of the 'repair' buttons sorted all this out.

From FreeCAD

This exported easily to an STL file: and then loaded straight into the host software.

From FreeCAD

It started to slice and print to gcode : it got to 55 layers through before I got bored and turned it off.

FreeCAD is currently alpha software so far, but certainly one to watch!

One step forwards

2009-10-10T20:20:00.004+01:00

G'day all.

I've been quiet recently - I had packed everything away into the garage as we were planning to move. Plans change, we're now not moving so I unpacked the RepRap and fired it up.

From ResistorHeater

First problem : blocked nozzle, due to a broken thermistor - overheated - and set the ABS solid.
Cleared down and drilled it out.

I replaced the thermistor with a spare 100k makerbot one - my last spare.

Interestingly enough, I soldered in a 100k thermistor from Maplins into a spare circuit, connected it up, and the temp read about 20C at room temp, and 34C while holding it - pretty good without any change in configuration. It might be a suitable replacement for the 'official' ones.

Replacement thermistor in, I warmed up the heater and 'let rip'

From ResistorHeater

It works! Extrusion is pretty slow (232mm/sec) and wide (nearly 1mm diameter through a 0.8mm nozzle) but it comes out reliably and pretty consistently. Temp was about 225C and power (screw thread/servo) at 180/255.

Now I have something working, I can refine the nozzle size ( I should be able to get some 0.6mm B&Q nozzles) and the original BfB 0.4mm nozzle, plus I have some small drills.

I now need to get my settings and speeds right in the host software - my current version is months old, maybe I should update. I've been thinking about upgrading to version 3 electronics, too, but with the excellent Mendel design out with a much smaller footprint, I quite fancy that. It might be time to build a Mendel using my Darwin....
:-)

Balls to the rescue

2009-09-02T18:13:00.004+01:00

Since I disassembled my MyVu Solo glasses, I've been looking for some optics to enlarge the image to a useful size. The stripped displays are only a few mm square.

From MyVu

I thought about trying a jeweller's magnifying loupe (the thing they use to look at gemstones), but they looked a bit heavy.

What I really need is some kind of curved mirror. After looking up in wikipedia, I reckon I needed a short section of concave curved mirror with a focal length of only a few cm. OK, where the hell do you get one of those?
Well, if you extend a curved mirror, you end up with a sphere. So, a mirrored sphere - a few cm across? Well, your local christmas shop!

From HMD

To cut a small square section, take a diamond-coated file and gently score the lines you want to cut....

From HMD

Or just explode it in you hands, like I did.
Taking a couple of the larger sections, the internal surface is pretty much mirrored. Too far away, and there is no image:

From HMD

But, at just over half the radius away:

From HMD

An enlarged, reflected image is formed. Since the glasses originally had plane reflectors in, I think it probably won't even need reversing - now to mount them in a test pair of glasses.

NOTE : safety warnings apply - don't play about with razor-sharp wafer-thin slivers of glass near your eyes. Like I am. If I stick glass in my eye it's my own stupid fault. Don't try this at home.

Laser Scanner

2009-09-02T18:11:00.000+01:00

Not strictly RepRap related, but I've been playing with the David Laserscanner software from www.david-laserscanner.com/.

It does seem pretty useful for generating source data. If it's good enough, you can scan an item, tidy up the data a bit, then print it put on your RepRap. The system then becomes a 3-d copier.

So, is it up to the task?

Initial setup:
You need a webcam, a laser line (either a laser level or a laser pointer), and the software.

I used an old webcam (640x480), and a red laser pointer (5mW) from ThinkGeek - but they're pretty readily available.

The software comes with a few different templates - basically a dot pattern you print out. You then attach the pattern to two sides of a 90 degree corner - like the inside of a box, or two card sheets at right-angles.

From laserscanner

You then point the webcam at the box, and 'paint' it with the laser line. The webcam can see the shadow of the line on the object and the background, and can work out the 3-d profile of the object.

To turn a laser pointer into a line, you need to bounce it off a curved surface (I made a line with a shiny metal knife handle), or shine through a glass cylinder. Wandering around Bath, I care across a shop selling christmas decorations - and they had a nice glass raindrop - shape:

From laserscanner

Shining the laser through the glass cylinder produces a nice line:

From laserscanner

I snapped off a short section of the glass and polymorphed it to the front of the laser. I've now got a simple laser line.
Initial playing with the software gives an idea of the result - I think it needs a bit of careful configuration to get the best scans out of it, but the potential is definitely there.

From laserscanner

Quick-release extruder

2009-09-02T17:44:00.002+01:00

I pulled out my reprap at the weekend and fired it up. After levelling the bed, checking calibration, and fixing the z-flag that was loose, I started the extruder....

Nothing came out.

After some fiddling, I disassembled and reassembled the heater/nozzle - it was fill of brown/grey ABS, absolutely rock-solid, and had to be drilled out.

Since this is about the 50th time I have disassembled/reassembled my heater/nozzle assembly, I tried a modification to make it easier to change. My PEEK insulator is bolted to a penny washer with an m8 thread and two half-nuts.

From quickrelease

I cut a slot in the penny washer and I can now loosen a bolt and slide the extruder barrel/heater out to change it.

From quickrelease

This came in really handy, because as I restarted, warmed up to 225C, and fed the ABS through - it stuck fast. At least I could disassemble to find the problem.

The ABS appears to form a solid plug of the brown overheat mess as soon as it hits the heater, going solid and blocking the tube.

I think I've got a broken thermistor, or maybe the heat transfer is bad. It seems to warm up as expected, and reports the right temp (ish) staring about 16C and rising to 225C - fluctuating about 223-226C, but the ABS is definitely overheating.

I'll swop it out with another one and see if that helps.

MyVu Solo displays

2009-08-24T23:09:00.002+01:00

Here's the photo of the bits remaining after breaking up the glasses:

From MyVu

The remaining useful pieces are two microdisplays with controller: one and one half-optics sets (I cracked one mirror).

From MyVu

I'd sliced the cable between the two PCBs during disassembly and found that they don't turn on if the second display is not connected, even with a bit of fiddling. Trying to strip the FFC (Flat Flexible Cable) to try and reattach it just didn't work - the connectors are about 0.2mm wide at that point and I just cut more and more off.

From MyVu

Farnell came to the rescue: A 20-way 0.5mm pitch FFC (A to A) for £1.54 did the job just as well. I plugged it in to both displays and they're both up and running.
Here's a mini southpark episode:

From MyVu

Now all I need are some glasses and some magnifying lenses....

Jiu-jitsu - 1930's style

2009-08-23T21:08:00.002+01:00

The coolest kung-fu video I've seen for a long time!

http://www.youtube.com/watch?v=wmP1uKOVTr4

:-)

No disassemble - part 2

2009-08-17T19:23:00.004+01:00

Just to finish off the breakdown of the myvu glasses:

Once the outer shell has been removed, you are left with a small plastic unit containing two clear plastic blocks, with the displays at either end. They appear to be solidly glued in.

I ended cutting the block in half using wire cutters. The plastic is moulded in two parts, but is pretty solidly attached or glued. I then had to cut away and snap bits with pliers to uncover the plastic prisms.
Once the prisms are removed, the remaining plastic can be snipped away to uncover the displays and tidy them up a bit. Be careful of the diagonal ends of the prisms - there are small glass mirrors glued to the ends, and I chipped one.

I now have two uncovered displays and two plastic mirror/lenses. They can be re-mounted in a more suitable frame (maybe reprapped?)

Another step forward

2009-08-16T20:24:00.002+01:00

Dusted off the old reprap today.

I warmed the heater up and extruded a few cm of 1mm extrusion - through a 0.8mm nozzle, the print quality won't be too good but it should be quick. The extruder actually seems to work reasonably well!

I then had to fix the acrylic Z-axis flag, which has cracked and broken off - the flag holder and also the opto-endstop holder. A big lump of polymorph worked really well at replacing both cracked acrylic parts.

I then had a massive headache so I put it down for the afternoon.

Nearly there - time to try a print soon.

No disassemble Number Five!

2009-08-16T19:41:00.003+01:00

Today I took apart a set of MyVu solo glasses to extract the displays. I thought it might be useful to post some photos to help anyone else following my path.

From MyVu

I built my own phono lead to connect a composite source - the cheaper version only comes with an Ipod lead. Pinouts for the myvu solo 4-pole 3.5mm connector are:

Tip - left
ring - right
ring - a/v ground
body/ring - video

This happens to be the same as the Zune media player. Connect the grounds (outer rings) from the phonos to the a/v ground, and the tips of three phonos to the left, right and video.

Starting point:

From MyVu

A bit of experimentation with the screwdriver found that the front cover is held on by a couple of plastic tabs, and with a bit of levering comes off pretty easy.

From MyVu

There is a plastic frame in three parts holding everything together. It is screwed together with four torx screws - two neat the centre bridge, and two behind small plasic covers forming the arm pivots (the hinges for the folding bits).
I drilled these out as my driver was too big, causing a bit of damage.

From MyVu

The signal is generated in the control box and fed up a many-core wire into a small connecting PCB on the left side of the glasses.

From MyVu

The signal appears to be split and sent across to the right-hand display using the (damaged) flat cable. This can be unplugged at both ends. The right-hand end is simpler, only connecting to the right ear piece.

From MyVu

I cut the earphone wires and pulled out the rubber housings from the arms. This allowed me to force the left arm apart freeing the cable.

Currently, the control box still works, although the video is not visible. I think it's because the backlight circuit probably runs through both LEDs in series, so I'll need to identify and patch that so I have a single working, monoptical display. Then I can re-mount it in a more 'socially acceptable' frame to form the HUD for my dataglasses.

DataGlasses

2009-08-09T21:56:00.003+01:00

I spent a few hours this weekend working on another project...

I've been interested in HCI (Human-Computer Interaction) for a while - it started as part of my job - and I got started with alternative input devices, mainly keyboards and mice when I suffered from RSI/carpal tunnel.

When I read about dataglasses (courtesy of the most excellent writer Charles Stross) I was fascinated. I wanted some. They sounded like such a good idea - a logical extension of wearable computer use, a real integration of the things computers are good at to provide a useful tool.

For the uninitiated, dataglasses are basically sunglasses with an integrated computer display - providing a head-up display - add in net access, camera to provide face recognition, clever software, and you start to get some really cool capabilities. I'll leave it to Mr. Stross to explain the details (and possible problems) in his book Accelerando.

Since no manufacturer seems to be producing them yet, I'll have to build my own.

Components:
MyVu MA049 Solo Plus personal media glasses
Old laptop with composite video out
An iphone headphone adaptor plug (Any 4-wire 3.5mm plug will do - like a normal headphone plug but with 3 divisions not 2)
Two or more webcams.

Phase 1:
Get the computer display onto the glasses display.
Actually a bit harder than it sounds - the glasses only come with an Ipod lead (at least the £45 I bought on ebay) and the extra connectors kit is out of stock. It's basically a 4-pole 3.5mm stereo jack, like a headphone plug, to phono plugs.

I found an 'iphone' headphone adaptor in a charity shop which had a 4-pole 3.5mm plug - so a bit of modding is in order.

I investigated the output from the Ipod lead and I think I've sorted the signals.

MyVu Solo plus pinout
4-pole 3.5mm plug

Tip - Left
Ring 1 - Right
Ring 2 - A/V Ground
Ring 3 - Video

I've hooked up the wires with some of my shonky soldering, but it's refusing to play ball so far. The glasses claim to be missing the video signal.

It's still a work in progress....

Doorstop Heater Block

2009-07-27T23:04:00.009+01:00

Wandering B'n'Q the other day, I checked the bargain bin and found this:

From ResistorHeater

It is a brass doorstop: Basically a 1 inch brass rod with a M6 threaded hole down the centre. It's just about the right size to make a heater block! And, it's reduced to £3!
I picked one up to play with.

Closer inspection revealed that the central threaded hole projects all the way through the block, stopping at the small indent for the O-ring.

I hacksawed through at the indent, cutting off a 20mm chunk - the m6 thread goes right through.
I drilled a couple of 6.5mm holes through for my resistors - and widened them a little, as my resistors are not straight, and added a small hole for a themistor.
Widening half the m6 thread to m8 allows me to screw in a Peek insulator.

From ResistorHeater

Here's a pic of the components:

From ResistorHeater

and assembled:

From ResistorHeater

Firing it up, I found that it reaches 220C in about 7 minutes, with no insulation. The heater seems pretty sturdy and well-attached. Starting up my (fixed) BfB extruder drive, I waited expectantly....

From ResistorHeater

Hurrah! It extruded several cm of filament - reasonably quick too!

If it starts up again later, then I might be able to build something soon!

Extrusion: 220C at motor speed of 120/255. Nozzle 0.8mm welding tip, 1.01mm filament

Fings I av Fixed.

2009-07-27T18:55:00.002+01:00

Since starting to build my RepRap, I've fixed much more around the house. Having the tools to hand, and having the confidence to try, means that I've fixed things where previously I would have thrown them away.

I've replaced the power plugs on two of our laptops several times.
I've fixed one of the laptops - including disassembling it, taking out the main PCB, de-soldering and changing over two SMT microswitches, and replacing the power socket.
I've fixed a couple of battery-operated kid's toys - simple things like disconnected wires and broken solder joints.
Recently, when the telephone cable was accidentally cut during some gardening, I replaced the whole section of cable - the old cable was past it, not worth joining.
I fixed a doll's arm back on.
I fixed the bathroom door lock - and several other jobs in the home, mainly because the tools were available and handy.

Also, I taught my daughter to solder - making a 'game of life' kit together. It went really well, and worked first time!

All this (indirectly) because of my RepRap.

Heater Blocks

2009-07-27T10:53:00.000+01:00

In my quest to ignore conventional wisdom and make my own extruder, I've started playing around with resistor heaters in blocks like NopHead.

I looked around for a while, and found a mild steel block (30x30x10mm) at my local engineering suppliers. They also supplied me a couple of 1 inch (25mm) cubes of copper.

With one of the steel blocks, I drilled two 7.5mm holes laterally and filled them each with a resistor wrapped in tinfoil to provide a tight fit (and better heat transfer). I drilled a 5.5mm hole through the block and tapped it to M6 thread.

From ResistorHeater

With an M6 welding tip, I extended the m6 thread to all the way down the barrel. Then, drilling it out to 3.2mm, I made a mistake and drilled it all the way through. I now had a short copper tube with m6 outer thread. This screwed through the heater block, leaving 5mm top and bottom. The existing BfB nozzle screws nicely onto the copper thread.

Screwing a m6 coupling nut onto the top allows me to connect a drilled stainless steel bolt. Stainless steel is a poor conductor of heat - not as good as PTFE insulation, but helps stop the heat transfer up the shaft.

From ResistorHeater

Firing it up, there is a lot of thermal inertia - it takes a while to get going (2-3C per second). It finally tops out at 210C without any insulation. The stainless is not a brilliant insulator - it gets fairly hot (70C) at the washer/support end, but should be usable.

Learning more and more

2009-07-21T20:51:00.002+01:00

I've been building more nozzles and drilling some holes in metal. I tried drilling out a stainless steel bolt to make the extruder barrel, but it was hard work and didn't feel right. Usually when that happens, I'm doing something wrong...
So, I googled and read up on drilling into stainless steel.

Apparently, when the drill rubs over the metal in the hole, it starts to heat and work harden a thin layer of steel - making it harder and stronger - and more difficult to drill.

The advice is to drill at a slow to medium speed, apply lots of pressure, and drill few mm then pull right back to clear the swarf. This is pretty much the opposite of my original technique.

This works *really* well - you get lovely long spirals of swarf (razor sharp splinters) and the hole is much easier to drill. I found it much easier to drill out welding tips and have drilled a couple of stainless bolts using the afghan lathe technique.

Top Tip: Read instructions before using.

What is a RepRap?

2009-06-18T06:52:00.000+01:00

Excellent introduction to RepRap

RepRap from Adrian Bowyer on Vimeo.

BitsFromBytes extruder

2009-06-11T16:40:00.005+01:00

Reading a comment on the RepRap forums I *finally* realised that BitsFromBytes had a Forum and a separate Blog. Since I've got an older v2 kit, I hadn't checked back there for a while.

While catching up on the blog, I found a really useful post by Tony (copied below):
MK2 extruder
I was able to get some very nice results from the original GM3 powered BFB extruder, all the same principles apply, keep the melt zone short and support the PTFE close to the heater. Stability of the motor speed and the quality of the motors were the only slight issues. I ran both single and twin motor versions for many months without a problem. I still believe this original extruder design is very good and it certainly proved itself reliable over that time.
For those who had problems getting them to work I strongly suggest you blueprint the design exactly as it should be, by all means sharpen the thread and undercut it with a hack saw if you must but this should be the limit of the mods. The most common error I have heard about is the omission of the small reaction washer behind the main feed screw. Miss this out and you will never grip the filament tight enough. Build the extruder exactly as the instructions and it works, mess with the PTFE add custom heaters and coach bolts for the drive screw(what!), and you are in unknown territory. Run it how it should be first, get some experience in printing, you will then start to see where modifications would pay dividends, the original one works very well and starts reliably from cold.

Coach bolts? Who would do such a thing! :-)

Time to re-check. If it's only me and one or two others having problems with the BfB drive, then it's probably either my setup or incorrect assembly.

Re-state the problem.
Initial problem: heater/motor control worked fine, but extruding at 250C and any speed only resulted in 2-3mm/minute, almost too slow to see. Tried various temps and speeds, same result.
Removing heater, I was able to manually pull the filament through (screw thread not biting).

Tightened all the bolts - still no change to extrusion. Tightened to the point the acrylic started to crack (on the 2mm plate holding the bolt/filament roller). No change. Springs fully compressed. (reaction washer in place)
Disassembled, sharpened bolt thread with die. Better grip, but no better extrusion.

Examining the heater and drive separately, found that the heater required a reasonable force, but extruded OK, but the drive system still wasn't strong enough - although it seemed more than strong enough during testing, it still wouldn't extrude.

I then experimented with some different nozzles and drive systems. I found some nozzle designs needed less force, but needed careful machining to be reliable.
Replacing the m8 thread with a coach bolt , which had a much larger, sharper thread really gripped the filament very well - but still didn't extrude. WTF?

I think the problem is the thread is very grippy - but the pitch is about 4 times larger than the m8 thread. The coach bolt drive is very strong, but drives faster than the m8 thread - a few mm per revolution. I think pushing too fast chokes the extruder, stalling the filament, and stripping the filament (confirmed by examination). It might work very well, but needs to be geared slower (or driven by a stepper).

OK, so after reading the BfB forum and posts, I stripped down my extruder to have a closer look.
A careful inspection of the extruder parts revealed this:

From BfBExtruder

The heater bolts are *slightly* too large for the channels in the extruder drive, causing a gap between the plates. This meant when I removed the heater to check the drive system, it closes up - and the drive works properly. When I screwed in the heater to check the extrusion and bolt to the reprap, the bolts screw in - the gap opens - and the pressure is taken off the screw thread. The screw doesn't bite the filament, and doesn't pull it through.
Bugger.

I'll file the channels out, reassemble to the original BfB extruder, and try again. I think it *might* just work this time (famous last words...)

As we say in computing, PICNIC (Problem in chair, not in computer)....or should that be PIANID (Problem in Assembler, Not In Design)...

Presentation over!

2009-06-09T17:35:00.003+01:00

Today I managed to show my RepRap to 50+ colleagues at work (IPL).

We have a lunchtime talk every few weeks, on technical and non-technical subjects, given by staff and invited contributors. I foolishly volunteered to give a presentation on my RepRap.

I put together a little presentation, some notes and delivered it today!

It went really well. Everyone was attentive and I got some sensible questions, so some of them were listening! After the talk, I started up my RepRap and it ran through a dummy print, since my extruder isn't quite working at the moment.
Lots of people stayed to watch, and there was some lively discussion over what could be printed, and everyone seemed interested.

As usual with presentations, you get really nervous before, but after a couple of minutes that goes and I really enjoyed showing off my RepRap.

To IPL'ers, thanks for listening and showing so much interest!

Top Tips for improving my presentation:
Lots of questions on possible materials and what could be printed (i.e. overhangs, support material, etc).
Concentrate on the 3d-printing of other objects and introduce the self-replication as a side-effect: Also need to mention upgrading itself using printed parts

Tips, Tips and more tips

2009-05-31T21:13:00.004+01:00

I've recently ended up with a whole bunch of welding tips and some tattoo tips.
I thought it might be interesting to compare them.

From RepRap_bits

Sources:

Halfords SIP Welding tips, 0.6mm or 0.8mm hole, M5 thread - 5 for £4.99

B&Q, MIG Contact tips, 0.6mm or 0.8mm hole, M6 thread - 5 for £4.99

Ebay, Tattoo tips, various sizes, no thread - 18 mixed for approx £10. can be bought singly.

From RepRap_bits

Halfords are the smallest : an M5 thread, and a short body (18mm). B&Q have a larger M6 thread and are nearly 24mm long. Both welding tips are copper, and the tattoo tips are stainless steel. The tattoo tips have a long barrel, but a huge hole for a rubber band in the side. (white line is 3mm standard ABS filament)

From RepRap_bits

The nozzle holes are all similar sizes. the first two are 0.6mm Halfords. The next two are 0.8mm from B&Q. The tattoo tips come in various sizes. These are the two smallest round holes: I think they're designated R1 and R2, and look to be a similar size to 0.6/0.8mm. Some of the tattoo nozzles are much larger.

From RepRap_bits

The shapes are very different: the Halfords tip has the 'best' shape, a 45degree taper. The B&Q has a flat tip - it might cause the extrudate to stick, although it would be easy to reshape with a drill and file.
Both the welding tips need to be carefully drilled out - typically 3mm - to within a whisker of the exit hole - so that the thin section is as short as possible.

The tattoo tips seem to be made by drilling a 6.8 or 7mm hole, then a 2mm? hole right through - then a tube of the required dimension is (brazed?) attached to bring the diameter down to the exit hole, and the tip shaped(guessing). From visual inspection, it looks like the 2/2.5mm hole extends almost all the way to the tip.

From RepRap_bits

I think that if the excess tube is 'trimmed' it will form a good nozzle shape internally.
The tattoo tips need to be attached and/or the big hole in the side sealed. a few initial thoughts are:

tap the internal diameter and screw in a standard reprap drilled bolt
cut an 8mm thread in the outside and screw into a coupling nut or threaded block
drill a 'heater block' like nopheads to 8mm and press-fit/solder/braze the tube to form a good seal.

I'll have a play with them (I've got 18, so plenty of spares) and see if anything works.

Of course, if 0.6 or 0.8mm is too big for you, you can always use the nichrome wire/high temp solder trick to get a smaller exit hole.
Since solder is a generally softer, has anyone tried blocking the hole and drilling the solder with a small drill bit to get a 0.4 hole?

Hacked Firmware for simple encoder

2009-05-30T22:24:00.002+01:00

I've started hacking the firmware to add support for my simple speed controller.

Current version is here:

http://sites.google.com/site/renoirsrants/reprap/software-i-use

Warning: this is straight off my development version. Read (and modify) before using.

speed 1 = fast
speed 255 = slowest

It *should* run encoder at a constant rate.

Finding parts

2009-05-27T19:12:00.004+01:00

The key to finding RepRap or RepStrap parts: keep your eyes open, and don't be afraid to ask: experiment, try things out, and tweak your design to what you can find. I've found a few useful bits over the last couple of months.

I wanted to add an encoder to my GM3 drive motor, but I've previously blown my three spare opto-switches.
Asking around at work, I found an old ball mouse with a broken USB plug, and got permission to take it home from sysadmin.
Logic dictated that running off USB (5v) it might contain some opto-switches that I could recycle. Taking it apart, a quick inspection revealed two components either side of a slotted wheel that looked right:

From RepRap_bits

I desoldered them, ripped out the broken IR sensor from the x-max endstop board, and just soldered them in.

From RepRap_bits

Hooking it up to the arduino, it works perfectly!

Other extruder bits:

I found some thin-walled alumininum an brass tube in a Model shop in Westbury. It's imperial (5/32) but the internal diameter is exactly right for my 3.1mm filament.

From RepRap_bits

I think it might work well to make vik's no-lathe/ariel extruder, or to make a Nophead-style thin-walled extruder. I've got a large heatsink from a core2 CPU to go with it.

I've been looking for a block of metal to make nophead's resistor heater for a little while - it's not something you can buy in B&Q, and I don't happen to have aluminium bar stock in my garage. :-)

In the middle of Bath, down by Sainsburys, I walked past a little tool shop that was selling scrap metal outside. I went in and asked, and...

From RepRap_bits

Hey presto, the chap disappeared out the back and came back with a 10mmx30mm bar - and cut me off a couple of 30mm lengths from it. The best bit : cost 25p. So, a shout-out to the guys at Avery Knight and Bowlers, Bath - thanks guys. They've been consistently helpful and the shop is full of tools and other useful bits. I also grabbed some m6 coupling nuts - might be useful to attach nozzles - and a 7.5mm drill, which is the right size for my resistors.

I've thrown a few quid away on some tattoo tips from a dodgy overseas company (like these ones). I wanted to have a look to see if they would be useful to turn into nozzles. When (if) they arrive, I'll post some measurements and photos.

Edit: half-hour after posting this, I noticed a big split in the mains cord insulation for my wife's hairdryer. 'It's not safe, we'll have to you get a new one' - of course, nothing to do with the fact it's full of nichrome wire....

Radio Renoir back on the air!

2009-05-26T18:29:00.003+01:00

Sorry it's been a bit quiet recently, I've been off work with depression. There's been a lot going on in my life, and it all got a bit too much. However, the doc gave me some stronger tablets and I'm back to full form! Everyone's been really supportive, work have been great about it, really understanding (thanks D and J).
While I was low, I wrote a really rambling, bizarre post that make no sense at all, trying to explain. Glad I didn't post that one!

Very little progress made on the RepRap in the last month. However, I'm putting together a talk for my work colleagues on 9th june, so I'll post a copy of the presentation when I'm done. I'll also write up the couple of tweaks I have made, and some new bits I bought today.

BRB

Extruder design thoughts

2009-04-30T23:22:00.012+01:00

I'm going to throw down some random extruder thoughts, untested theories, and probably re-iterate most of Nophead's proper research. I apologize for any complete rubbish or plagarism

ABS

ABS isn't really like chocolate, or ice, which is a simple solid or liquid.
When cold, it's solid and can withstand quite a lot of force in compression. This allows us to force it down a tube and use it a bit like a rod or piston to force the plastic into the nozzle.
When it warms up, you can bend it easily.
Warm it more, and it starts to soften. Because it's being pushed down, when it gets soft it tries to get wider, pressing against the sides of the tube. At some point, it becomes 'molten'.
'Molten' ABS isn't really liquid. In some ways, it's like plasticine or clay - it needs to be forced through a nozzle, it doesn't really 'flow'.
It's also a bit elasticy at times - when you stop pressing down, it can dribble on slowly for a bit, until it's evened out the pressure.
And finally it's a bit like melted mozzarella - pizza cheese. Pull the melted filament out of a heater, and you often get a really long, thin stringy bit - just like a Domino's advert.

Designing an extruder

Lots of my extruder designs have worked to a greater or lesser extent. It's not *too* hard to make an extruder work once, it's reliability and repeatability that cause my problems.

A larger heater chamber (4mm/5mm diameter) works OK, but the extra ABS takes longer to warm up and melt.

The shorter the 'melted', hot section the better, - preferably as near to the nozzle as you can get. Also, the less metal you have, the less thermal inertia you have, so it heats up quicker. The quicker it heats up, the quicker it cools down while extruding - so the heater power has to be controlled.

PTFE is a good insulator, and it's easy to machine - you can cut an 8mm rod with a sharp craft knife, and it's easy to drill. You can cut a thread easily with a bolt or nut. PEEK is much stronger and requires proper machining - use a tap/die to cut threads.

PTFE is soft, and when it's hot it gets softer, so it really needs extra support (external bolts and washers, etc) to hold the join to the heater barrel still, and extra pressure to avoid leaking plastic out the side. 8mm PEEK rod is strong enough to have a welding tip screw-in (tap an m5 thread) and easily holds the pressure.

The join between the barrel and the insulator is very important. This is where the ABS becomes softer and the filament will get wider and fill any gaps in the channel.

Quite often, my extruder experiments work the first time, but after cooling and re-heating are much stiffer and difficult to get restarted. After inspecting the cold filament, this is because the ABS flows into any small gaps and then solidifes when cold. The entire assembly will then be stuck until the gaps have melted.

If the extruder is hot but not flowing for a long time, the heat will flow up the ABS, softening and widening it further up into the insulator. At least PTFE is very slippery and it helps getting it restarted.

I think NopHead's design, with the thin aluminium tube insulator, excellently avoids the join problem. If you can cool the barrel further up, so that the melt occurs inside the barrel, this problem doesn't occur.

Nichrome / Resistors

Both Nichrome wire and resistors both work reliably and reach the temps needed. Nichrome wire needs more preparation and a layer of insulation - Fire cement, jb weld, or Kapton / kraken tape. If you connect your normal wire to the nichrome by knotting it, or using a crimp connector, it's much easier to wind on and you can hold the join safe inside the fire cement or tape. Nichrome is very flexible, you can wind it on the barrel, nozzle, or both.

Resistors are nice, self-contained heaters. They work well, but you need to transfer the heat from the resistor surface to the nozzle. This means either embedding it in a drilled block (like NopHead) or my low-tech solution of shoving them inside m8 coupling nuts (as I don't have any solid blocks lying around). Either way, they're larger and need more metal (therefore more thermal inertia, slower heater), and not quite as flexible as the assembly is big and chunky compared to the nichrome wire.

Both methods work well.

Nozzles
Ideally, the nozzle should be removable.
Ideally, to keep the heated section as short as possible, the heater should be close to or on the nozzle.
Both of these requirements can conflict :-)

Welding tips (0.6mm) from Halfords, £5 for five, work pretty well as nozzles or even combined barrel/nozzles. They need to be carefully drilled out to 3 or 3.2mm almost to the end, but be careful. I've wrecked four trying to drill to 3.5mm to get a better heater entry, the walls are just too thin. The central hole helps align the drill centrally, even drilling by hand works OK, but I'd use a 1mm then 2mm then 3mm bits first.

I've had reasonable success with a PEEK insulator, a welding tip, with nichrome wire wound directly round the welding tip.

Have a go and see what you think :-)

More Extruder Experiments

2009-04-30T16:42:00.005+01:00

Time to write up the past few weeks of experimenting in making extruders:

From Renoir6_Extruder

This is a quick extruder made from a short section of 5mm brass tube, 8mm PTFE rod with a central 3.2mm hole for the filament and an experimental PTFE nozzle.
The PTFE is drilled about 8mm in to 5mm diameter, and the tube is push-fit into the PTFE.
The nozzle is made from 10mm PTFE rod, drilled almost to the end with a 5mm diameter. Part of the outside is shaped down to 8mm (to fit a large washer for support) and tapered a bit. The final breakthrough was done with a .35mm hand drill where the PTFE is about 2mm thick.

The heater is made from a couple of layers of kraken tape and some (partly) insulated nichrome wire reclaimed from a previous nozzle.

Warming this barrel up, the tape didn't appear to be affected, so I fed some ABS down. it seems to melt fine, filling the 5mm brass easily, but I hadn't bolted it down properly to hold the PTFE together, and I pushed the nozzle off before it came out the 0.35 hole.

From Renoir6_Extruder

It had been at 220C for a half-hour or so, so I deconstructed it to see if the kraken tape was damaged:

From Renoir6_Extruder

It seems to be unaffected. The covering you can see on the nichrome is the original insulation: it seems to decompose and can easily be scraped off with fingers, but even where the nichrome is just bare wire the kraken tape is unaffected. This isn't a long term test, but it's promising.

From Renoir6_Extruder

This extruder uses a brass tube, and a PTFE nozzle and insulator as above, but uses a different heater. Two wirewound resistors are placed inside M8 coupling nuts. The nuts are then held together in a vice and a 5mm hole is drilled between them.
The two coupling nuts can be placed around the brass tube (or even a welding tip) and held together with tape. you can also pop a thermistor between the tape and the nuts for temp monitoring.

To provide pressure to the PTFE tube joints, a large m8 washer is placed over the nozzle (10mm PTFE rod turned town to 8mm) and bolted to the existing BfB extruder drive (using the enhanced coach bolt drive).

From Renoir6_Extruder

This warms up fine to 220C and extrudes with some force. This PTFE nozzle has a 0.6mm hole, about 0.5mm thick PTFE (thin enough to see light through) but is still able to contain reasonably high hand forces. It extrudes, slowly, but immediately expands to a much larger extrusion.

From Renoir6_Extruder

Eventually I decided to re-build a more traditional extruder. A couple of taps with a hammer broke up the fire cement and allowed me to reclaim the nichrome, m6 BfB barrel and nozzle.

From Renoir6_Extruder

Using a combination of learning from my experiments, I've built yet another version:

From Renoir6_Extruder

3ohm nichrome heater directly around the nozzle, and 4ohm above. PTFE screwed to nozzle and also secured using bolts and washer. Washer heat isolated using a turned PTFE washer - also holds the m6 barrel nicely in the m8 washer. kraken tape insulating the heater. Coach bolt hack on a BfB lasercut extruder drive, standard GM3 DC motor/gearbox. Standard BfB aluminium nozzle.

I'll see how this one performs soon... :-)

Don't try this at home

2009-04-24T20:21:00.008+01:00

I misused an electric drill to make a temporary lathe.

Using the drill and some scrap wood, I could slide the drill up and down in line with the bit. Very carefully, you can drill holes straight along PTFE or PEEK rod to make an insulator.

I managed to drill a nice straight hole through the PTFE and PEEK.
It seems to work for plastics: I'd definitely get a more secure setup before drilling brass or steel bolts. Even this hacked-together setup is more accurate than (my) drilling 'by hand'

Full story

Silicone tape

2009-04-18T10:57:00.003+01:00

Wandering through a Maplins store the other day, I came across this:

From Renoir5_extruder

It's silicone tape, and is rated to 260C - high enough for an extruder. One of the suggested uses is for repairing car exhaust systems.

I made a temp extruder heater out of two m8 coupling nuts, two wirewound resistors and a few inches of tape. It seems to hold up well, and went up to 220C.

From Renoir5_extruder

I need to re-drill some welding tips, since I widened them to 3.5mm and made holes in the sides.

One step forward, one step back

2009-04-11T09:19:00.004+01:00

My jerry-built extruder is blocked.
The coach built drive is still working fine, providing quite a bit of force to the filament - enough to dear big chunks out of it.
The extruder nozzle is blocked.

This happened before, during hand testing. I've restarted and stopped the nozzle several times, and only twice had a jam. Last time, clearing the 0.6mm nozzle hole with a pin did not restart the flow, so it isn't a nozzle blockage. Providing *excessive* force suddenly cleared the blockage and restarted the flow, where it went back to normal.

There is one factor that was the same between blockages.

Both times, immediately before, the filament had been left in the nozzle, and the nozzle had been left hot for several minutes, while testing other stuff. Then the nozzle was turned off and cooled down (end of testing).
The next day, the nozzle was blocked.
On other tests, either the filament was withdrawn while hot, removing the bulk of the plastic, or after extrusion the heater was switched off immediately. Restarting the next day was fine.

I *think* what happens is that the heat travels up the filament, softening and widening it. Over a couple of minutes or so (if it cools immediately) this isn't a problem. If the heat is applied for several minutes, the filament softens further and further up, pressing against the sides of the channel, causing more and more friction. Because my insulator isn't uniform (there is a .3 mm step near the top, and a hole across (see screwdriver drive) this gives plenty of friction - blocking the filament channel. This is why clearing the nozzle doesn't help.

I'd suggest that if you're not using the extruder, or between days, turn the heat off - or better, withdraw the filament an inch or two while hot. My fully assembled extruder worked well, but last time I was testing the axes and trying the sort out a software bug, and I left the extruder hot for 20mins or so while doing so. The next time, it's solidly blocked - no extra force is shifting it. I'll either have to leave it hot for a half-hour or so to see if it softens enough to shift, or disassemble and drill out the stuck filament.

I went out yesterday and bought a small vice (£4.50) and a reamer like Nophead's (£3.00). I'm planning to use the Afghan Lathe technique to make a new extruder insulator with a larger melt chamber (4-5mm?) and a tapered entrance to see if this helps.

Coach bolt hack working

2009-04-05T16:53:00.003+01:00

I ran up the BfB extruder with the coach bolt drive. Drive is a little inconsistent, but works (12mm/sec or more).

It should be enough to let me build another extruder - i.e. RepStrap itself, with a traditional V1 or V2 extruder.

From Coach Bolt drive

I might try and build a coupler out of polymorph. My solder join is only straightish (a couple of degrees off) because it wasn't held very well while setting. I could also try supergluing a similar reinforcement with the slots - I don't think it will be strong enough on it's own.

I've mounted it on the RepRap

From Coach Bolt drive

And it should be ready to go soon. I tried using the host software to build a 10x10x10 square, but it started moving the Z-axis down, away fron the endstop. I'm not quite sure why yet... I'll try the replicatorG and the g-code to see if it has the same effect.

MORE DETAILS

Coach Bolt Hack

2009-04-05T10:07:00.003+01:00

The M8 bolt in my BfB extruder hasn't been gripping the filament well. I've tried the standard tricks, sharpening the thread, increasing the force (until I cracked the acrylic), but I'm still able to pull the filament out by hand against the thread. While shopping around, I came across some coach bolts with much deeper, sharper threads. Simple replacement of the M8 bolt was difficult - there aren't nuts that fit and it was impossible to attach the existing gear or provide vertical support.
I needed a bolt with m8 at one end for the gear and bearings, and coach bolt screw at the other for the filament bite. So I made this:

From Coach Bolt drive

It's soldered together ( see pictures for more detail of how), but if I had an extruder I could easily have made a coupler, since the joint is in compression.

From Coach Bolt drive

It seems to fit OK into the BfB assembly, with a little modification of the bearings (one bearing, rearranged nuts to fit). It grips the filament lovely now, and hand-winding the gear drives the filament well.
I then attached my rebuilt extruder nozzle.

From Coach Bolt drive

I'll post later when I've tested the nozzle.

Extruder thoughts

2009-03-30T23:34:00.003+01:00

I've been extruding all weekend so I thought I'd share my thoughts.
NB I'm not quite as organised as Nophead, so no pretty graphs and figures yet.
Friction and barrel size seems to have a big effect on the force. I built two heater barrels to the same design:

One had 3.2mm PEEK hole and 3mm welding nozzle tip. Filament *just* fits into the 3mm heater section (requires a little force).

Heating to 240C allows good extrusion with hand powered force.

One to the same design had 3.5mm PEEK hole, with a short 3.2mm section near the barrel. Nozzle was drilled to 3.2mm and filament fits easily.

Heating to 220C allows good fast extrusion with less force.

I suspect that the half-melted filament expands before melting fully and presses against the sides of the barrel, causing extra friction. I suspect that's why nophead's reaming made so much difference - a little extra space allows the filament to expand as it heats.

I also think my BfB extruder probably does work if the screw thread is adjusted correctly. Nophead has reached >12Kg with the screw extruder, so mine slipping is probably due to the spring/acrylic flexing and allowing the ABS to slide. I'll see if I can tighten up the pressure (maybe use some steel reinforcement) to drive the thread properly. Then I'll have to rebuild the heater barrel.

Three heater barrels and a new drive

2009-03-30T19:34:00.005+01:00

I made some extruder barrels over the weekend:
(click on the links for more pictures, design and test results)

From renoir1_extruder_quick_v0.01

quick and dirty extruder

From renoir2_extruder_v0.01

Version 2 - Welding tip

From renoir3_extruder

version 3 - wider feed channel (3.5mm through PEEK) for the filament

And I mucked around with a minimalist drive (Keep it Simple)

From Renoir1_extruder_drive

Simple - shove a screwdriver in a hole
This worked OK - as long as it was driven at a slower speed than the screwdriver default (2.4v instead of 3.6v)
I also had problems driving the screwdriver motor from the RepRap electronics

From Renoir2_extruder_drive

Version 2 used the BfB motor. Plenty of torque, but I can't drive it slow enough!
Below about 50/255 the motor stalls: above, the speed and torque is good but it stalls the filament once it hits the end and chews up the filament.
It works well (filament speed is aprox 5mm/sec at the 3mm diameter end) and as much drive as the filament can stand. The star screwdriver bits work well and seem to drive well. Perhaps I'll have to get a stepper motor and driver circuit for the extruder to get the speed down?

I'm going to try and reconnect the original BfB screw thread drive to my version3 heater barrel, and see if that drive will screw down at a slower rate.
*embarassed* I can't exactly use the original BfB heater barrel anymore- I was drilling some out stuck filament when the drill snached and ripped off the ends of the nichrome wire and threw the thermistor circuit across the garage. I still haven't found it...

Extruder progress

2009-03-29T19:09:00.001+01:00

I spent the weekend building extruder nozzles and drives and finally managed to build one that might work.

I'll write up the details of the working/not working designs over the next few days.

Chocolate Extruder

2009-03-25T20:19:00.003Z

Although my RepRap isn't quite there yet ( the ABS extruder isn't quite working), I have experimented by building a chocolate extruder from copper pipe fittings and a drill:

From choc_extruder_v0.01

A copper tube and bowl hold melted chocolate which is fed to a drilled-out welding nozzle via an auger made from a drill. The heater is a standard nichrome wire and fire cement, along with a 100k thermistor, connected to the standard RepRap arduino electronics.

Drive for the auger is provided from a Tesco Value 3.6v rechargeable screwdriver. Currently, this is manually operated as I'm having a problem driving the motor using the PWM DC driver.

From choc_extruder_v0.01

The heater took a while to heat up, but the entire apparatus reached target at 60 degrees C. Shoving a few chunks of chocolate in, it melted very quickly.

Extrusion worked much better than I expected: when the motor was off, there was a very slow drip of chocolate through the 0.6mm welding tip (approx 1 drip every 5 seconds).
With the motor on, I was able to extrude a steady stream at several mm/sec and drew some lines on the plate. With the motor in reverse, chocolate was actually sucked back up the nozzle!

From choc_extruder_v0.01

All in all, I'm pretty pleased with the experiment so far. I've written up some construction details at chocolate extruder. A couple of photos are on my picasa album.

Still to do :

Drive the motor from the RepRap electronics DC motor driver board

Design/build a mount (probably when I get my reprap working)

Print a chocolate object!

As soon as I've printed something, I'll post some pics. Might be a little while as I'm trying to get an ABS extruder working first...
:-)

New parts arrived

2009-03-23T18:04:00.000Z

I ordered some bits'n'pieces for extruder experimentation and modification. I grabbed some 8mm PTFE, 10mmPTFE and 8mmPEEK rod from DirectPlasticsOnline , and I ordered some wirewound resistors from Farnell, along with some thermistors and a set of 10-way pins and headers so that I can unplug and change extruders easily.

I spent some time in the garage cutting and drilling to make some simple insulators - and found that it's hard to drill vertical holes without a lathe or pillar drill. I also collected together some scavenged parts - some large washers, plumbing bits and drilled out a few 0.6mm welding tips to 3mm.

Sunday afternoon I spent soldering on the 10-way headers, and wiring up a couple of extruders. I'll test them out soon.

BitsFromBytes slow extruder

2009-03-22T12:01:00.003Z

Detroit RepRap Builders

Notitieblokje

I have a similar issue with the BfB extruder, very slow extrusion. Checking out the alternatives, the heater and nozzle seem to be similar to other designs, and with additional force it seems to extrude OK. The obvious difference seems to be the drive mechanism.

There's two main possibilites : the screw drive and the heater resistance.
My guess is the screw thread can't generate enough force to push the extrusion through and slips. Once it slips, it chews up the filament and can't get going again.

Give that Nophead's produced some useful figures for the extruder nozzles and forces produced by the pinch wheel design, I'll see if I can measure the output and identify the problem side.

Quick and dirty extruder design

2009-03-16T20:22:00.003Z

Combining several recent ideas from the forums, I've put together a quick and dirty extruder design. It uses many of the labour-saving tips (welding tips, the BfB 'big washer' design, Nophead's excellent resistor work) provided by others.

The PTFE runs right into a copper pipe end stop, which has an M5 drilled and tapped hole to allow a welding tip to be screwed in. The welding tip is *carefully* drilled out to provide minimal resistance to the extrusion.

Heat is provided by 2x 12Ohm resistors (wirewound, 6W, max 350degreesC) wired in parallel (which I reckon should give me a 6ohm load). Two resistors - one for either side of the nozzle - and they're squashed between the copper pipe end, nozzle, and a big washer on the bottom.

The big washer provides support to the PTFE barrel and is attached to the motor through long bolts.

I'm now soliciting any comments or advice before having a go at building this.

Possible problems:

ABS melt leaking along the side of the PTFE join?
Not enough thermal inertia to keep the melt hot?

Possible improvements:

Pack the gap around the resistors with FireCement to improve heat conductivity?
Use silicone 'washers' to help seal the joint between PTFE and copper pipe?

Any comments or suggestions welcome.

My Reprap

2009-03-09T22:25:00.002Z

Added some static pages describing My RepRap and my current setup. I'll post updates and built objects on the blog too, but it's sometimes easier to have a static list. I've added some pages for planned/built objects and ones found on the web.

My 'Workshop'

2009-03-08T19:28:00.004Z

On the RepRap forums, there are several users who have access to some pretty good workshops, either using college or school facilities, even those with lathes and CNC machines at home.
I'm not one of those users.
Here's a picture of my workshop:

It's my dining table, covered with an old curtain. I have a box of tools containing the following items:

several small screwdrivers
allen keys
some small pliers, needle nose and flat
two small wirecutters
soldering iron, stand, helping hands
some small needle files

I've also got a garage full of junk, but it's also got a black'n'decker workmate, and some standard DIY tools,including a small hacksaw and electric drill.

That's about all you need to build a RepRap from a BitsFromBytes kit. Obviously, if you have a full-size workshop, things are much easier - but my RepRap sits behind the TV most of the time. Building from scratch or from a RepStrap would probably be a bit messier and needs a bit more time and equipment, but building from a kit can be done in your living room.

It helps a little if you can dedicate some space for a permanent setup (a boxroom or office would do nicely) but my RepRap is sturdy enough to get it out when I'm experimenting and put it away between times.

Choi Hawarang Do

2009-03-07T14:16:00.009Z

I've just finished a session of Choi Hawarang Do at the Martial Arts Leisure UK. It's a martial art, based on effective self-defence and personal development - a really positive direction.
Inital impressions:
Everyone was really positive and friendly. Right from when I first walked in, Jenny , the assistant instructor, was welcoming and helpful, and everyone was willing to help along a new person, explaining what was going on and making sure I was OK. I was surprised and pleased at the mix of ages and people there - there was a good selection of older and younger students, right down to age 10 or so, and several ladies. There was none of the 'macho' atmosphere that is sometimes associated with martial arts and it all felt warm and friendly.

After the standard line-up and introduction, we did some guided stretching as a warm-up, and then onto the lesson. I was quickly paired off with one of the senior grades to show me the basics of the stance, and a basic block, punch and kick, and to run through the first block/punch/kick sequence. Once I'd shown that I was no ninja by wobbling through the simple kicks and punches, we rejoined the main class for a 2-on-1 exercise - where you simulate two 'attackers' (holding pads as targets) against one defender. After a few minutes, there was a quick break for a drink of water and then we ran through several self-defence techniques, including getting out of a headlock, a choke hold and a bear hug. A final line-up ended the lesson.

It made me breathe pretty hard at a couple of points - perhaps I shouldn't have spent the last couple of years on the sofa watching TV. That's good, because I needed a bit of exercise.

I'll definitely be back next week.

Configuration of XYZ axes

2009-03-06T20:52:00.004Z

I spent some time writing a long blog post about some testing and configuration, and then realised it was almost a set of instructions. I re-wrote a few lines and posted it on the RepRap Builder's Wiki, in case it was useful for anyone else. You can find it here:
http://objects.reprap.org/wiki/Builders/Config/Getting_Started
and a couple of pages here:
http://objects.reprap.org/wiki/Builders/Config_Methods

Basically, I've configured the X, Y and Z axis, so that if you tell them to move 10mm they move 10mm.

I did find that the x-axis stepper was slipping, as the x-axis wasn't consistent. I disassembled the stepper and took off the grub screw. I filed a larger flat on the shaft of the stepper, and re-assembled, making sure the grub was tight on the flat. It moves much better now.

I have just started to test the extruder... more soon.

It's alive! It's alive! The beast is alive!

2009-03-03T22:21:00.005Z

I finally got round to applying the electrodes and waking the beast from it's slumber (I plugged in my RepRap).
It's been stuck behind the TV for a while until I had a free evening to start configuring and testing everything. I spent an hour sorting out an Arduino communication issue (I'd foolishly uploaded the firmware compiled in test mode, and it kept saying 'start' down the comms channel).

Using ReplicatorG, I was able to jog the x-axis a little back and then forth - which worked!
I then wiggled the y-axis a bit - and that worked too! Then Z - both up and down worked!

With my hand on the PSU power switch, I gingerly pressed the 'home' button for the x-axis. The x-axis moved back to the home position, triggering the endstop and stopping on it's own! Then the same for Y - and Z - Things are going really well!

I spend a few more minutes winding the x, y and z back and forth. All was well until a z-home caused the wobbly z-flag to hit the side of the endstop, meaning the bed tried to ascend to the attic, winding itself into the print head on the way. The z-axis on the motor slipped, meaning that the bed was badly skewed before I got to the power switch. The z-belt also fell off.

I put it back together again - I don't think it's damaged but it gave me a scare.

Note to self: Hand on panic button ( the PSU power switch) until I'm really confident it's working.

Java! Reprap Host software!

2009-03-02T18:21:00.004Z

I spent most of the weekend getting the official host software working. The 'host' software is written in java, and uses several external libraries. After lots of fiddling, I got it working. The biggest problem was getting the RXTX libraries - I had set the LD_LIBRARY_PATH but I'd misspelled the directory name. The java software compiled OK, but didn't run as the native .so files were missing.

Once I'd got that running, I was getting preference file errors - all sorts of missing settings. Eventually tracked that down to a reprap.preferences file in ~/.reprap that came from a previous attempt early last year - well out of date. I replaced that with the latest reprap.preferences.dist and all was well.

The latest software looks much better - a better UI, and easier to understand controls. Skeinforge looks great for complete end-to-end prints, for dumping 3d models to a configured system, but the host software has easier options for configuration and testing. I've still got a bit of tweaking the options to match my setup.

RepRap Software

2009-02-26T20:24:00.009Z

Over the last couple of days, I've installed the RepRap software on my tablet PC. Last time I didn't have much luck, but this time I've sorted out the Arduino issue I had before. The /dev/ttyUSB0 port has restricted permissions - you need to run the Arduino software as root to enable the 'USB' select. I'm not sure if it's a general issue or just on my laptop.

The Skeinforge scripts are a set of Python scripts that slice a model and write G-Code (text code to control a CNC/RepRap). I got them up and running and sliced some example files.

I'm not sure if I'm doing something wrong, but when I slice the example minimug.stl, I get longtidudinal slices (C-shaped) as it tries to build the minimug on it's side. There doesn't seem to be an option to rotate the file in the scripts.

I fired up AOI (Art Of Illusion) and built myself a replacement minimug oriented differently. When I pass it through the skeinforge now, it seems to slice into better slices (circles) as I expected. Here's a few layers:

You can clearly see the raft laid down underneath the object, the base of the shot glass and the circular layers building up. It looks like the walls will be 2 layers thick.

When running the code through ReplicatorG (to pass the code to a simulator or the real RepRap) it appears to draw over the outer circle several times. I have yet to test this out for real...

At least I know the toolchain to build an object, slice it, check the G-code and then attempt to pass it on works...

I'll try to build an object soon.

Jay Leno does 3d printing!

2009-02-26T07:07:00.002Z

American host Jay Leno describes a commercial 3d-scanner and Dimension 3d-printer:
Jay Leno's Garage
It shows the scan/print process for copying a rare physical part, describes how a 3d-printer works, and shows off some very cool examples of physical prints.
A good primer on what the technology is in 5 minutes

Nuggets of truth

2009-02-14T16:00:00.003Z

Just found this on B3ta. Made me laugh.
NSFW (sweary) How Not to fail at life

Does seem to contain some nuggets of truth that I agree with.

Digital Footprints

2009-02-13T18:57:00.003Z

Everywhere you go on the web, you leave digital footprints.
Every web site you access, you send your IP address, user agent (which browser), which page you want, when you wanted it - and most of the time this gets written to a log. No-one tends to ever read it, apart from counting up a few stats, and eventually the log gets rotated to long-term storage or deleted.
It's a bit like walking on a beach with a crowd - eventually your footprints get washed away, and unless someone is trying really hard to find you, it's quite difficult to get anything useful.

That's just to start with, though.
Every time you touch the web you're adding to the information trail.
Post on a forum, post your facebook status, update your profile, edit a wiki, even shopping sites tend to track your viewed items to identify your likes and dislikes.
Every single touch adds. And it's not just the text of what you post - you can infer a lot of information from when and where posted. Even what you don't do can provide useful info. If you're running a shopping site, and one paticular item is viewed a lot but does not result in sales, this could indicate that a competitor is undercutting you, or you need to change the description.

Be careful where you step!

Google Stalking

2009-02-10T21:59:00.008Z

On the flip side of my privacy discussion, I've had reasonable success tracking people down on the net: having done it a couple of times I thought I'd share my successes.

In these few cases, I spent a half-hour or so with google: most of the time, it was pretty easy to do, keeping potential matches and scanning through a lot of chaff, and building a consistent profile of the 'target'.

Case 1:
I wondered what kind of people were in the mod team with me? Starting from their forum handles, I google'd a few. A few had pretty common handles, but one had a pretty unique username. I chucked it into google.
This produced about five or six forum profiles. Most had almost no personal info, but one had a link with a real name, also pretty rare.
Running the real name through google produced some interesting results. Several hits were from a paticular country, which I already knew matched my target's country.
Then I struck gold. Google returned the website for a band, where the keyboard player had the target's name. Even better, there was a picture of the band at a practice showing the target. Some of the info about the band indicated that they were together at college.
Combining one of the band members and the target's name returned a word document containing a college class list including the two names. The country and area matched, so I was pretty sure it was correct.
This gave me the name of the college and even the class ID. Googling again, it returned a handy timetable of the lessons for the class including the lecture theatres, dates, and subjects.
To recap, from an 'anonymous' name and hidden profile on the original site, I was able to find a picture, real name, school and timetable. In theory, I would have been able to stand outside waiting for the target.
(I later sent the photo to my friend in an online chat session - he was extremely surprised as he wasn't even aware the band had a site!)

Case 2:
I was looking for an old school friend, someone who'd been to my primary school. Starting from Friends Reunited, she had an account profile there but hadn't checked there for a while.
On her profile, she mentioned that she'd contributed some research to a paticular wiki article and she now lived in London.
Checking out the wiki page, the history gave me the list of edits. Of the article, most of the text had been added at one paticular point by one user, and all subsequent edits had been spelling mistakes, rewording and grammar correction. I had a pretty good bet that the username who added the main chunk of text was my target.
This username had also been discussing edits on another page, which I found on wiki search. This new page also had edits by the user, and one of them linked to a flickr photo.
The flickr photo gave me a flickr username (different) but checking through the other photos by this user, and reading the comments, confirmed my suspicion this was probably the target.
Google then was able to give me the other places that this flickr username had been used. I concentrated on the forum hits that included photos from the flickr account and found a regularly used forum that contained several of the flickr links. The forum poster username was different again, but shared a common topic linking it to the other usernames.
The new forum was interesting: it was a 'local' forum for a paticular area of London, and was quite happy to give me a list of posts by a paticular user.
At one point, discussion had touched on a paticular local shop, mentioned in other posts by name.
This gave me the exact local area of the poster. Combined with a couple of the flickr photos of 'my new flat' and 'the park across the road', and the googlemap ariel photos, I tracked down the exact building.

I stopped then, because it was getting creepy and felt voyueristic. Total time : 48 minutes (including half-watching Eastenders).

This was a person who did not have a big online presence, used multiple usernames, and stuck to general internet saftey rules (no addresses or real names in profiles).

This method isn't guaranteed, and does depend on building a likely profile of the target, crosschecking with what you know. You also end up wading through lots of chaff, but if your target has a relatively unique name it's a lot easier. You can also cross-ref with the location (town, country) and anything else you know, such as hobbies or interests.

Happy stalking!

Online Privacy

2009-02-05T18:41:00.009Z

I'm generally a pretty cautious guy with my online life. I've read the horror stories, seen people make *huge* mistakes and generally made a prat of themselves online (e.g. posting photos of yourself drinking when 'off sick', etc). So, although I've been using the internet in various forms since the late '90s, to start with I never had a blog, didn't have any online websites, and only communicated by e-mail. I was strictly a consumer only.

My strictly regulated privacy has slowly and gradually slid away until now, I'm posting a couple of times a day to random people I don't know via twitter (dave_renoir) quite happily. How the hell did I get from there to here?

The first step was probably forums. It started with one or two cautious posts, jealously guarding my email address, to stuff I really needed. One by one this crept up from a simple question and answer until I finally realised I actually sometimes knew more than some of the other regulars and started answering questions rather than answering them. In 2001, I got into building maps for Half-Life 1 and ended up joining a 'mod' team where I was introduced to the joys of chat rooms and direct messaging. I was still pretty cautious, and only chatted to a few people, but for the first time I'd given my real email address to someone I hadn't seen! The world didn't end, I didn't get hacked, and in fact, everyone I'd met was actually pretty nice (Hi to the T:FfF team!).

A couple of years later, I took up Aikido. I'd been to a several lessons and was pretty committed, so I set up a small website for the club (www.trowbridgeaikido.co.uk). I wrote up a few articles on the basics, a bit of publicity material, and really needed to post an email address so readers could ask questions. I took a deep breath, and posted my real address, waiting for the torrent of hate mail and spam that would inevitably follow.

I was pleasantly surprised. There was no increase in spam and no bad mail. Over the last 5 years, I've had about 30 polite questions which have been easy to answer and about 3 targetted mails from chinese martial arts maufacturers. I've only had one possible 419 scam, from 'the Nigerian National Judo team' wanting to hire our hall for the 2012 olympics.

The social networking sites started the same way, thin end of the wedge. I created an account on Friends Reunited to look up some old friends. Then it became a facebook account, just used to monitor and keep up with my family, who have adopted it wholesale. Even my mum and dad (silver surfers) have an account.

About this time, I started building a RepRap, and started this blog primarily to track my progress and to help anyone else building one. After a break to have hand surgery, I've started posting again.

I sat down and thought a lot while I was off - it was pretty much all I could do without my hands. I came to some conclusions:

Most people are either pretty nice and polite or just don't care. There isn't a large pool of 'stalkers' waiting to catch the unwary.
The 'signal to noise' ratio is so large on the net that only interested people are likely to find your postings.
Only people I know are even likely to be interested in my rantings. And they're probably just being polite.
Tracking down people on google is already fairly easy, and there's already enough there for a motivated user to track me down.

I came to the conclusion that there's not really a lot extra to worry about - the genie is already out of the bottle. I don't do anything that I wouldn't chat to a stranger about, and if they want to be bored by the geekiest nerd in existence then I'm quite happy to tell them all about it.

I might as well make the most of this new technology stuff. So I'll post more.

Added feet

2009-02-04T19:08:00.003Z

To avoid the rods scratching the table, I added some feet :-). I know some have reprapped them, but I haven't quite got it adjusted yet.

I went down to Wilko's and picked up a pack of 4 rubber feet and a pack of carpet coasters. The rubber feet worked pretty well the wrong way up, the holes for the screws were a bit larger than the rods. I wrapped the ends of the feet in insulation tape and the feet wedged on nicely.
I then superglued the feet into the carpet coasters, making some nice large rounded feet.

Worked pretty well!

Alternative Electronics mounting

2009-01-31T20:04:00.009Z

After looking at the darwin, and winding it up and down a few times, I found there is quite a lot of dead space inside the frame at the bottom. The z-axis cannot travel all the way to the bottom, because the motor and belt assembly prevent it.

With a bit of measuring, I found that the PSU and the electronics could be fitted inside the dead space.

I cut a chunk of plywood to size that would take all the PCBs. I found some non-conductive solid foam in the garage, and cut a couple of strips. Sticking the strips along the plywood, the PCBs can be mounted with some small bolts, without the undersides of the PCBs touching. The plywood and PSU are mounted to the frame with cable ties. They seem to be holding things together pretty well so far.

The x and y steppers leads were too short, so I extended them with some 4-core speaker cable and re-attached the plugs. The extruder leads I also extended, giving it plenty of slack to move around and reach to the PCBs. The power supply leads are now situated right near the PCBs so they plug straight in.

The biggest risk is a stray cable being caught up in the belt and either being ripped out or jamming up the belt. Make sure all cables are securely attached with cable ties and can't touch the belt. I routed all mine along the outside, underneath the lower sqare of rods and then direct to the sockets. The arduino is tucked away pretty much in the center of the space.

This arrangement protects the electronics and means that from the outside, all you need is the USB cable for the arduino and the power for the PSU. I think it also looks slightly neater than the boards on the outside, but since the Darwin is unlikely to win any beauty awards (only engineering ones) it probably doesn't matter too much :-)

Blowing the IR home sensors

2009-01-31T16:44:00.004Z

When my full kit arrived it contained limit sensors for home/end for all the axes - i.e. 6 sensors. Although I soldered them all, lazily I only attached the three home sensors to the build.

During testing with the stepper exerciser, I started getting some unusual symptoms. sometimes the stepper would only move in one direction (e.g forward and not back) and the 'home' buttons did nothing. Trying to find the range just sent the motors heading away from the sensor.

Finally, I worked it out and tested the sensors separately. I'd wired the 3-pin plugs backwards (+5v/grnd reversed) and this had blown the sensors. Even when there was nothing there, they reported closed. I guess I'd blown the IR source.

Luckily, since I'd been lazy earlier, I had three untouched boards. Once I'd rewired the 3-pin plugs properly, the arduino test program correctly reported open and closed when I blocked it with some card.

I replaced all three sensors and the homing function worked properly. The clear acrylic from the BfB kit doesn't block IR, so I glued some card squares to the moving pins to block the IR.

Tuning the stepper circuits

2009-01-31T15:14:00.003Z

Once I'd plugged in the installed steppers into the driver circuits, initial testing showed that the heatsinks got *very* hot. After a couple of minutes, the x-axis started to 'jiggle' - oscillate about half-a step backwards and forwards making a juddering noise. I switched it off.

I moved each potentiometer to minimum, and the steppers stopped moving completely.

Using the stepper exerciser and the 'home' command, I set the axis moving. Turning the current up slowly, you reach a point where the axis just starts to move. I gave it 10% above that and then stopped. That gave it enough to move all the axes reliably.

The heatsinks still got *very* hot, so I took off the standard ones, and grabbed a few from my spares box. Due to a few years of rebuilding PCs, I had several PC heatsinks around (for those who are interested, they are a from a 486dx2, a Pentuim 75, and an Athlon 800). I drilled a 5mm hole near the edge and slapped them on. Now, even after a while, they only seem to get warm.

I also extended the stepper plugs using some 4-core ribbon speaker cable.

Extruder (2)

2009-01-30T16:26:00.003Z

After completing the heater, I warmed it up to 220 and put through some ABS.
The motor ground through a few cm of extrusion! it works!

Pretty soon, though the filament stalled and the screw ground down the filament. Feeding through by hand started it again, but it needed help.
I had to experiment a bit to get a consistent extrusion. Things that helped:

I bought a cheap tap/die set and ran a die down the bolt thread to sharpen it
tightening up the screws and springs pressing the filament onto the screw
upping the temperature to 240 *really* helped. I think at 220 it's only just hot enough. I'm still not sure that thermistor reading is accurate.

I still need to configure the temperature thermistor/heater power to get a more consistent temp - it tends to creep up slowly to over 255.

Extruder assembly (1)

2009-01-30T16:04:00.003Z

I bolted together the complete extruder assembly.

I finished off the extruder and tested it. The barrel gets hot, the temp reader goes up and the motor starts on request. Result! or so I thought.
After testing, it seems that it wasn't getting hot enough. I measured the temp with a digital kitchen thermometer, and the difference was significant.
After a bit of investigation, I found I had the wrong include file for the thermistor in the arduino code. Switching it and re-loading the arduino gave me a much better reading - the kitchen thermometer (touching the outside of the barrel) now reads within 10 degrees of the thermistor (buried inside the fire cement).

I also insulated the barrel using a section of silicone plate mat. Tesco's had some reduced at 10p each so I picked up a couple. This equalized the temperature between the heater top and bottom.

Progress update

2009-01-30T15:58:00.004Z

Time for me to put in a progress update on my RepRap: Here's what it looks like today:

It's mostly together and working - it just needs calibration and testing!

I'm going to write up some further posts detailing how I got to the current stage, including mistakes and changes, in case there's something that helps anyone else.

Normal service has been resumed

2009-01-25T13:47:00.002Z

Sorry about the 'slight' (read 4 months) delay since I last posted. I had some serious problems with RSI/Carpal tunnel in both wrists, and ended up being off work for about three months. I've had surgery on both wrists and now things are much better. I've been back at work for a few weeks now, so I'm confident enough to restart working on the reprap and blogging again.

Extruder assembled

2008-09-18T07:15:00.003+01:00

Extruder kit mostly assembled. The fire cement winding was easier than I expected - I ended up curing it on one of my electric cooker rings which worked well.

Huge progress!

2008-09-15T07:08:00.002+01:00

This weekend I spent several hours building and made huge progress

Building the top frame. Note the extra 70mm bars temporarily inserted help make sure the gap is straight, and also that the 20mm wide spacer bars help you get the minimum 20mm overhang correct.

Completed frame with diagonals. All travel is smooth, all I need is to hook-up and test the motors and wind on the belts. On to the extruder!

Lower frame square

2008-09-10T07:07:00.003+01:00

The lower frame is built and square. Note: don't overtighten nuts. Use your fingers to hold the nut rather than a tool as it prevents cracking the acrylic.

A variety of other corners and parts of the y-assembly.

Complete x-axis and some brackets

2008-09-02T21:20:00.005+01:00

Here are the lower brackets and the z-motor support

The complete X-axis assembly!

Progress

2008-08-20T09:43:00.006+01:00

The main reprap bed parts

Download and print instructions from bitsfrombytes

A hobby box (this one is a cross-stitch box) keeps your nuts seperate

Some sub-assemblies from yesterday

I'm having fun.
:-)

Kit Arrived!

2008-08-18T22:37:00.006+01:00

I've been a bit quiet as my RSI is playing up and my wrist hurts so I have been off the computer for a bit.
Instead I will post some photos.
Normal service will be resumed asap.

rods

extruder kit

lots of bits

Final stepper board complete!

2008-07-30T06:54:00.003+01:00

Last night, I completed the final stepper motor driver board. I re-tested all three and all three leds light up nicely.
The final board went very smoothly. I'm finally getting a bit more confidence with soldering, and third time around I knew where most of the components went. I started after the police dogs program last night, and finished just before big brother, so it took me almost exactly one hour.

Timings for each board (starting from scratch, with little soldering experience, pretty cautious):
Practice - 1.5 hrs
Arduino shield, DC motor driver, PWM - approx 1.5 - 2 hrs each
6 opto-endstops - 2.5 hours total
stepper 1 - 1.5 hrs
stepper 2 - 1.25 hrs
stepper 3 - 1hr
(timings include setting up and tidy up for each session)

All in all, the electronics went better than I expected. Because of the separate boards, they fit well into doing a board during an evening. If you sat down and worked continuously, things would probably go faster - but I didn't have a weekend free.

I've been able to test the PWM and DC driver boards, but the steppers have yet to be connected to a real stepper.

Now, I'm just waiting for the bitsfrombytes kit to arrive...