Etched boards

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

From PCB

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!

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!

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!

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



Nice TV spot advertising!

Home-made (bodged) PCBs!

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!

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

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....
:-)