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This is not a PCBgcode problem, but I need some gcode help

Posted by Ray 
This is not a PCBgcode problem, but I need some gcode help
January 04, 2018 03:51AM
This is NOT a PCBgcode problem, but I just don't know where to ask for help.
I am having some problems with, I think, g-code, for PCB isolation milling.
I'm not sure that the g-code is the source of my issue, hence I don't know where is the best place to ask for help, so I will describe the problems, and maybe someone has an answer, or can point me to the best forum to ask for help.
I have produced the g-code for several PCB's now, using EAGLE to create the PCB artwork, and pcb-gcode.ulp, in EAGLE, to generate the g-code.
Using this g-code, I have successfully milled the isolation tracks (0.06mm deep) using Candle, having done a Height Map of the board in Candle and applying it to the g-code, before doing the machining. This has produced excellent, and repeatable results.
With that success under my belt, I decided to investigate other methods of producing the artwork for PCB's where I had not produced the board in EAGLE, but by using a scanned image of a PCB out of a magazine.
I scanned some PCB artwork into PaintShop Pro, scaled it, and generated a Black/White high contrast image of the PCB.
I saved it and imported the file into InkScape where I generated an outline trace of the PCB tracks and saved that as an SVG file and a DXF file.
The SVG file I imported into MakerCam and produced the g-code to mill the isolation tracks.
The DXF file I imported into ArtCam and again produced the isolation milling g-code.
Both g-code files loaded into both Candle, and Universal g-code Sender, and visualised OK.
I loaded the ArtCam g-code into Candle and set up the mill, but without a milling bit, and the Z zero a safe height above the board, then sent the code to the mill. The mill and spindle started and proceeded to go through the actions to mill the board. Each time the Z axis moved down to do a cut, the Z axis showed -0.06 as the milling depth. The milling sequence finished completely. It looked like I would have done a successful mill with that run.
I then repeated the test with the g-code produced using MakerCam, and again, the results were as expected.
It was time to try milling a PCB.
I loaded the ArtCam g-code into Candle and performed a Height Map, and applied the Map to the g-code. I set up the X,Y and Z co-ords to Zero and sent the code to the mill. The mill lifted the Z axis to move to the first milling site and started the spindle, but just continued moving, eventually hitting the top of the Z axis, and would have eventually hit full Y positive, had I not aborted. All this happened within the first 20 or so lines of code.
I tried again, with the same results.
I then loaded the MakerCam g-code into Candle and performed a Height Map, applied the height map, zeroed the machine, and sent the code to the mill.
The Z axis lifted, and the mill moved to the first milling location and started to lower the Z axis, when I aborted. The spindle hadn't started.
I repeated the trial but at a safe Z height. Same results, and the mill continued to trace the isolation tracks to the end. If the spindle had started, it would have been a normal milling exercise.
I have repeated these tests several times, with the same results. Everything seemed to work fine, until I apply the Height Map, then things go pear shaped.
I thought the spindle not starting would be an easy fault to find, but I found the M3 command after the Z axis was lifted to start moving to the first milling location. I am used to seeing M03, not M3. I changed it to M03, but it did not fix the problem.
Any advice or assistance would be greatly appreciated.
Again, sorry for asking this here, but I just don't know where to ask.
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