Milling PCB's

Brian Carpenter

Who has mastered this so far with their home machines? I have a Probotix comet CNC and have done lots with it so far. But i have not done pcb milling.
I use Diptrace to design PCBs. What is the process from their to get them to my cnc?
CNC sofware i have is VCarve and Cut3d from Vectric.
What software is required to created the gcode file?

JasonDorie

VCarve will do it - I think DipTrace will export DXF files. You specify how many passes you want it to take, how much to step away from the traces on each pass, and so on. It generates a set of outlines for the traces which you then import into VCarve. From there you use VCarve to profile cut on the lines at the depth you want, and VCarve is what outputs the GCode file you run on the machine (or files if your board is double sided). It takes a couple times to figure out good step values & cutting depths, but it's pretty easy to do overall. I started with a very simple circuit that was just a TSOP chip to header pin breakout. Once I got that to work making full circuits was pretty trivial.

Also, DipTrace will directly produce a drill file that Mach3 will load to drill your holes, and it can also export DXF files of the silk screen layers - if you have a pen attachment you can use micro-sharpies to draw the silk.

These are the bits I use for cutting the traces: http://www.drewtronics.net/

This is the first PCB I did: http://www.youtube.com/watch?v=PPPoKnK6aiY

The biggest circuit I've done so far is for the room lamp, here: http://www.facebook.com/media/set/?set=a.10150172173803973.344728.671403972&type=3&l=4320ebfe4f

There's a well written article here: http://www.chembal.com/cnc/mechanical-pcb-etching
He uses Eagle, but the methods are very similar.

W9GFO

Diptrace has the option to export a DXF in an 'outline' format so that you can perform isolation milling.

GordonMcComb

JasonDorie wrote: »

The biggest circuit I've done so far is for the room lamp, here: http://www.facebook.com/media/set/?set=a.10150172173803973.344728.671403972&type=3&l=4320ebfe4f

This is more than impressive! :thumb:

-- Gordon

Erik Friesen

I have done a little small stuff. One key is a flat table. What I would recommend is making a small vacuum table, and surface it. Without surfacing your base, you'll have trouble. I had the best luck milling around .005 to .010 deep. I use cut2d and the dxf export feature. For simple stuff, you can hand select the drill points out of the dxfs. It can get kind of complex figuring out how to mill correctly, as you need to figure out which side of the line to mill, unless you export from diptrace with the offsets already calculated. Be sure to build your board like you want it routed, with minimal clear area. One gotcha with diptrace is that it doesn't export ground planes properly, perhaps someone else has an idea for that.

EMC2 has some rotation features that would work for two sided boards.

Duane Degn

JasonDorie wrote: »

I started with a very simple circuit that was just a TSOP chip to header pin breakout.

Jason, do you have pictures of any of your finer detailed work?

I noticed your room lamp board used all DIP chips.

I'd love to see pictures of your TSOP milling.

JasonDorie

The TSOP was the header being cut in this YouTube clip: http://www.youtube.com/watch?v=PPPoKnK6aiY

It was for a 1mm spaced ribbon connector for a CDROM motor. Unfortunately I don't have any pictures of it and it's the only thing I've done that was that small. The end of the video shows a decent scale shot. I'm currently using a 60 degree bit, but a 30 would be better for fine pitch work because you can cut a little deeper but still keep the isolation paths narrow.

Erik Friesen

Not necessarily though. 30 degree is extremely easy to break, at least the bits I had.