I’m just getting started with PCB milling on a new Nomad. I’m having a couple of problems related to tool changes and zeroing when drilling.
I’m using Eagle with the pcb-gcode plugin to generate the gcode for the board and then running the etch and drill files with Carbide Motion, starting with single sided boards so I get that right before hassling with double-sided. I start by connecting, zeroing by bringing the engraving bit just into contact with the board, running the “etch” file, and then reloading the “drill” file (leaving the zero setting alone) and running it.
The drill gcode contains tool changes and I get prompted to put tool 1 in. After changing to the first drill size and clicking continue, the machine measures the length of the bit, and then returns to the board and moves the tip of the drill bit into contact with the board, apparently punching through the copper layer (fortunately this doesn’t seem to have broken the bit). Carbide Motion then prompts me a 2nd time to insert the same tool, remeasures it, and then returns to the board without punching into it, and then starts the spindle and drills successfully.
When it gets to the 2nd drill size I also get prompted twice and it punches into the board (in the zero position I think) again.
What’s causing the machine to hit the board with the drill bit, and why is Carbide Motion prompting for the tool change twice?
I don’t know anything about GCode but I looked at the file and did a little googling and my suspicion is this bit:
M06 T01 ; 0.0320
G01 Z0.0000 F20.00
The change to tool 2 has the same sequence later in the file. If my Google-fu has not abandoned me, this looks like a tool change, followed by selecting the first bit, followed by a move to zero height, followed by a second tool change. Are these redundant M06 commands responsible for prompting twice? Is the move to Z0 responsible for the bit hitting the board?
More importantly I suppose, what have I got wrong in Eagle, pcb-gcode, and/or Carbide Motion that is causing this in the first place?