FlatCam and bCNC for Scratch Milling

  • Import front and back gerbers, excellon drill file.
  • Offset to mill area.
  • Use 2-Sided Tool to flip back copper and drill files. Check work.
  • Set isolation routing on copper, generate geometry.
  • Start milling once front is ready to save time.
  • Set tool params (create defaults), generate CNC job.
  • Save CNC code, label files.
  • Set drill speeds and feeds (create defaults), apply to all tools.
  • Select drill sizes one by one, generate CNCJob per drill.
  • Save CNC drill code, label files.

bCNC

  • Connect, Reset, Unlock
  • Make sure correctly zeroed.
  • Open top layer G-Code file
  • Make sure bit is scriber, and cleared height for x,y movement.
  • From Probe tab, Autolevel, press Margins, then Scan.
  • Make sure probe circuit is connected to board and ground.
  • From ending Scan position, set height less than 1 cm above board, zero Z, probe.
  • Set Z to zero at surface, raise bit slightly and begin Autolevel.
  • Move bit up, board to front access, apply 2-3 coats of Magnum Sharpie ink, or layout fluid.
  • Scratch mill board.
  • Inspect board, flip by sides if satisfactory (if not, adjust your z depth and notes, remill).
  • Repeat all steps for back side. Use spacer or mill cavity to avoid smushing the ink.

Etch the board

Etch board, clean with acetone, clean with alcohol, tin board. See etching section.

Drill the holes

  • Place to back side of the board back onto the milling surface, secure with screws.
  • Double check it is in the correct orientation by looking at bCNC image still on screen for the back side.
  • Load first drill file, I use largest holes first because they are the strongest bits if settings need tuning.
  • Double check the drill holes and paths line up with the board. This is an easy step to get wrong!
  • Make sure your Z-height is high enough for the first drill bit, they are very easy to break.
  • Probe and zero board again. CAUTION: Not all areas on the board will be connected anymore due to the etching. Make sure you probe in an area that is connected by copper.
  • If that seems hard, manually probe with a paper. This step is not very Z sensitive as it is just holes all the way through.
  • Click Margins and run a Scan with the Z height sufficiently high. This serves as a quick sanity check and puts the drill bit in the starting X,Y position.
  • Drill each round of holes with the proper bit size. No need to remeasure the Z if using bits with a plastic collar (recommended).
  • Remove and inspect the board, it should be ready for soldering.

Next: Scratch-and-Peel Milling

Setting up you milling machine for auto-leveling: Scratch Milling on the Nomad 883