Quickstart/Latest on PCB milling?

Hey all - wanted to check in with the collective regarding the latest on PCB milling. I’m a pretty experienced Nomad user (fusion360–>carbidemotion->go) but have done mostly plastics and metals. A friend wants to cut a custom PCB and I foolishly offered that I think I can do that on my 883pro.

He’s using KiCad and we need to turn that into gcode somehow, which then gets sent to the machine through cb-motion.

What’s the latest thinking in terms of:

  1. base pcb material - capabilities/limits (ie. trace width and accuracy)
  2. process to go from KiCad -> [gerber?] -> gcode
  3. how do thru-holes get made (in the gcode that is)
  4. cutters to use to get good quality trace-cuts, speeds and feeds - depth of cut if applicable

Have read other, pre-existing, threads on the forum but they date back to 2015 or 2017 (some have broken images so hard to see/read them). So wanted to check in with the collective to see what’s the latest and greatest?

Thx!

  1. I’ve been doing scratch milling [1] with very consistent results. Mostly what I’ve changed since making that video is I do three contours, and then do each side twice. That removes any lingering copper that can cause shorts. I originally was trying to make boards faster, but it’s better to be more unsupervised with minimal post milling verification imo. 6mils is the smallest I go unless smaller is really needed - I’ve done areas with 4 mils but you really need to dial that in.

  2. KiCad/Eagle - FlatCam - BCNC (due to autoleveling). Those programs are a bit painful and have a learning curve, but give good results. I’m doing board cutouts with them as well.

  3. I just use the regular excellon drill files and PCB drill bits. Careful as each drill size can have a different height, so you will probably need to measure and record those once. For vias, I solder a tight fitting wire or twisted wire threads.

  4. I’m now using broken PCB bits, sharpened with a diamond plate [2]. Works just as good as scriber bits, and I can sharpen them for a few seconds before each PCB making things consistent. I use and XY speed on 2400 mm/s, about as fast as the Nomad goes. The milling is at -0.04mm depth, really just a scratch. It looks like it won’t even work on the first contour, but three contours run twice works every time in my setup at least. Too deep is bad, it gets into the FR4 and makes a mess of the edges.

[1] https://www.youtube.com/watch?v=VN0X4jVp4XI (scratch milling)
[2] https://www.youtube.com/watch?v=GLuZiUt88OQ (sharpening drills)

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Most schematic/PCB packages output Gerber RS274 code. This is an industry standard format (antique, but standard none the less). The software here : https://carbide3d.com/apps/pcb/ will accept the Gerber files and NCdrill files and help create the gcode.

Other companies have translators too (LPKF for example) but they tend to be proprietary.