Quick and dirty PCB milling with the Nomad


#1

Hi all,

I’m here to share my first “quick and dirty” PCB milling experience, hopefully to build up some karma for all of the questions I’ll inevitably ask in the future.

I’ve written this up super fast so sorry if there are mistakes or important information I’ve overlooked…

Basically I designed a board like this in KiCAD, and exported Gerber files:

(images combined at end)

It will be an RF amplifier so grounding is important, those white circles are holes for vias. The rest of the holes I did not intend to bother with, just the traces should be reasonable so that I can solder on some components. The “trick” is to make sure all cuts can be done with a 0.8 mm cutter, so that nothing fancy is needed, just the standard flat end 1/32" from Carbide 3D. I also checked how level the platform was on the wasteboard, over 5 cm left to right it was roughly 0.2 mm variation, so I supposed I’d just cut an extra 0.2 mm in (beyond the thickness of the copper) and that’s it.

So basically it’s three steps - cut out the traces, holes for vias, and then cut the board outline.

That was all set up in FlatCAM, another free and easy to use program (exported gcode files and ran them on the Nomad the normal way):

(images combined at end)

For the holes I used a drill bit of the appropriate size for the 1.2 mm “Favorit” rivet via tool thing (you can google details), though it can be done even simpler by using the same 0.8 mm cutter to drill the holes, and then just soldering in some wires for the vias. The rivet tool is super fast, easy, and high quality though, so worth the investment if you will make a lot of via’s in the long term.

Anyway, in my case it was the traces with the cutter, then the swap tool to do the holes with the drill bit, then back to the cutter for the outline. I don’t know what the RPM is, it’s not set by FlatCAM and I should have probably added a line in manually or something, whatever the “default” is seemed a bit slow but worked fine. I did the cuts 0.2, and then the cutout I did it 2.0 mm (1.6 mm thick PCB, it goes a little into the MDF wasteboard). I accidentally did the outline in one pass, probably not ideal but it did work. Finally popped it out and put in the rivets and it looked like this:

(images combined at end)

That little scratched spot is because I didn’t notice that the gap in the trace wasn’t quite implemented right, so the two pads almost connected, so I just widened it a bit. My mistake and nothing to do with the machine or software. Also, it’s two-sided FR4 blank from instructables, attached with double sided tape.

Anyway, it came out great and I’m super happy with it. I still need to solder on the components but I’m sure it will be fine. Next iteration will be trying to do more narrow cuts with a V-shaped tool or some such, you can find info on that elsewhere. Also I suspect either software or hardware leveling better than the intrinsic setup will be needed for finer details, and for 2-sided milling a repeatable flipping arrangement will be needed… to accomplish both of those things I will probably try to make a little vice with three screws for fine-tuning of the board orientation relative to the cutter… either loosely based on the “low profile vice” they sell, or by buying one of those and attaching the leveling setup.

Long story short - I’m super happy with the first results, which are quite good for minimal effort, great machine and I look forward to using it more.

http://imgur.com/UQI7Eo1


(Edward Ford) #2