Well, got my sherline/spectralight mill cutting, using GRBLShield. Very cool!!
Turns out that (one of) my problem was that the Inkscape Gcode generator was spitting out a frred rate of 400mm/min, which was, well, bad. All of initial by-hand testing had been done with the “default” feedrate of 100mm/min, which was working fine.
I wrote a littel g-code script that went to an offset, cut a square, and then cut the diagonals of that square, and finally returned (hopefully) to the origin. I changed the feed rate, and tested it out, initially because I was just too friggin’ impacient to wait for the milling to finish at 100mm/min.
What I found was that up to 300mm/min seemed to work fine for the seeking (although cutting at 300mm/min lost a couple steps), but if I set it to 400mm/min, the steppers just twitched, stalled, hummed, and then did nothing. (Which explains why my initial g-code test was so mangled.)
Can someone please explain to my what’s happening, and perhaps how to fix it? Do I need to apply more current? I understand that cutting too fast might be a problem, since you could try to move the cutter faster than it actually cuts, but as long as I meet the STEP signal timing, why would the motors stall?
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