Sunday, 28 February 2010

Schoolboy Error

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
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...

Saturday, 20 February 2010

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!]
From PCB

Friday, 19 February 2010

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.]

Thursday, 11 February 2010

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.

Friday, 5 February 2010

RepRap - As Seen On TV!

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

Nice TV spot advertising!