PCB milling.

Recently I had a go at milling single sided PCBs on my cnc mill. I’m super happy how the initial tests went out.

First of all - vaccum table was perfect for this task. I didn’t have to deal with double sided tape etc. - mounting of the board was painless. On top of that I got it flat, didn’t have to work around the bends of the board.

The test project has been designed in Fritzing - which for hobby / simple project comes as highly recommended. I didn’t have to go through manuals to get the design done, it has taken literally minutes to get it done. The only catch was setting hole spacing for the components- initially I’ve used default ones, which turned out a bit too wide for the capacitors.

For more complex designs it might be beneficial to learn KiCad or something similar.

Exported traces have been opened and verified in MoI (as it works nicely under WINE on my Linux laptop), then Rhino where with the help of madCAM plugin I prepared the job. It was mostly contouring strategy and a couple of pockets. For the engraving / cone shaped bits it’s important to check how the angle of the bit is measured in the CAM plugin vs the catalogue. For the first cut I was too eager to get started and haven’t noticed the difference - thus got slightly wider traces.

I’ve used a cone shaped bit with 2 cutting edges for the task. The RPM has been set to 14000 with a feed of 400 mm/min. This worked nicely, the cuts were clean.

Which I can’t tell about the second tool - 3mm flat end, which I usually use for aluminium. I’ve decided to use it for cutting out the outline of the boards. Tried a couple of feeds and speeds but each time the copper layer curled up and the edge of the cut was not clean. To counter it for the time being I simply traced the edges with the cone bit first. Will need to try different bits (maybe downcut ones will be better?), but at this point that does the trick.

So all in all - it has turned out to be pretty straightforward, can’t wait to try it on more complex projects.