It is getting so easy to order a finished printed circuit board that it is tough to justify building your own. But sometimes you really need a board right now. Or maybe you need a lot of fast iterations so you can’t wait for the postal service. [Thomas Sanladerer] shows how he makes PCBs with a CNC machine and has a lot of good advice in the video below.
He starts with Eagle, although, you could use any creation package. He shows what parameters he changes to make sure the traces don’t get eaten away and how to do the CAM job to get the files required to make the boards. If you don’t use Eagle, you’ll need to infer how to do similar changes and get the same kind of output.
We’ve only heard a few people pronounce Gerber (as in Gerber file) with a soft G sound, but we still knew what he meant. We have the same problem with GIF files. However, once you have Gebers, you can join the video’s workflow about 5 minutes in.
At that point, he uses FlatCAM to convert the Gerbers to a single G-code file that integrates the paths and drill files. There were a few tricks he used to make sure all the tracks are picked up. Other tricks include leveling a spoil board by just milling it down and mounting different size bits. He also has ideas on aligning the Z axis.
He first did a mock-up with some MDF scrap. The final boards, of course, use copper clad FR-4. Interestingly, the mock-up served as a position guide for the board. Even if you didn’t do an entire mockup, milling the profile of the board might be a good idea. Naturally, the first attempt wasn’t great and he aborted it. He simplified the board layout and tried again but that didn’t work well. He then switched out the engraving bit he was using for a proper end mill. That caused a bit of an edge that needed sanding, but solved most of the other problems.
It looks like for simple boards, the technique works ok, although there were some limitations. Some of the traces were the wrong width and some annuli didn’t survive the drilling. It also appears it isn’t reliable to place traces between IC pads using this milling process.