Monday, April 21, 2008


Plotting Gerber Files

In the long term the ideal way for reprap to produce circuity is by additive processes (laying conductive substances embedded in plastic objects). These processes are still being developed so in the meantime it would be pretty handy for RepRaps to be able to plot PCB masks onto blank boards with a pen so they can be etched.

I've been working on a Gerber (universal PCB format) plotting script for the last couple of days and finally have the basics working. The picture below was printed by my repstrap today and measures 32mm by 26mm. The thin lines are there because I still have no Z axis to lift the pen.

(I know it's mirrored, my X axis is inverted, needs re-wiring)

The original file in KiCad:

The script creates a photo plotter trace by plotting the straight line between start and end points, then by drawing the loci of the aperture movement from the start point to the end point at several intervals from the central line (diameter 0), up until the diameter of the aperture.
Good summary on gerber format

At present the script controls the RepRap directly over the serial port though I plan to add g-code export functionality.


Excellent work, looks like the Python stuff is gathering momentum!
Nice work! I guess we've got to get you an extruder that will print solder now. :-D
yeah, this is rad!

i think i'll try this out...
I made myself a rather basic z axis today from a stepper with a piece of thin cord on the spindle attached to the pen, so I've got rid of all the lines that shouldn't be there.
Great work. I've been waiting for something like this, and in Python too. That means it stands a good chance on running on an OLPC, which reaches another of my goals.

Once we're replicated - which from my perspective at least has to come first - I'll have some fun with this!

Vik :v)
Most excellent.

I think everyone else has summed up my thoughts in that this is something I realy need.

I guess it contributes very significantly towards the goal of being able to reprap...

PCB's included.

I think we need a pen holder for the Darwin.....
How well do the various plastics stick to clean (sanded + alcohol scrub) copper-clad boards?

The 'normal' method or making your own circuit board uses polymerized toner that just happens to stick. Several of the other plastics should also stick well enough.

If they don't stick well enough for an etching bath, you could run the _inverse_ image as a mask. That is, have the script 'fill' all the non-trace areas instead of trying to do all the trace areas. Then you'd have a stencil you could spray-enamel or otherwise apply something simple that won't come off in the etchant.

(Of course, if you really can skip the whole etching step, that would rock far more.)
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