Advice - Milling to the limits

[downrazor11 (Stephen)]

@luc.onthego

Thank you for the thorough reply Nathaniel, I was leaning in the same direction but did not want to play with resetting limits. I’m still using CC but I’m considering changing in the not too distant future. I will eventually have to deep dive into GCode because at the moment I can read most of the code, I’m not confident enough to mess with settings. I will reference your reply for future investigation.

I had problems when I made my first wasteboard, some of the holes on the edge ended oval instead of round so I learned to be careful milling near the edges. It is the first time however that I try milling on the south side of the southwest corner defined in CC…

Hi, I think the oval at the edge would be a different issue and would have to do with the stepper motors’ step size being slightly unequal, meaning if a step in the Y direction equals ‘1.000’ then a step in the X direction would equal ‘1.001’ or ‘0.999’ or something else, but not ‘1.000’ (like Y). This situation would make the step size mismatch most noticeable the further you get from origin (0,0). You would need to redefine the values for the grbl, namely $100 or $101, here is the list from the Shapeoko 3 wiki (I don’t know if these values are the same for version 1.x, I am still on 0.9):

CarbideMotion 0.9g
$$
$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=6 (dir port invert mask:00000110)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=255 (status report mask:11111111)
$11=0.020 (junction deviation, mm)
$12=0.010 (arc tolerance, mm)
$13=0 (report inches, bool)
$14=1 (auto start, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=0 (homing cycle, bool)
$23=0 (homing dir invert mask:00000000)
$24=100.000 (homing feed, mm/min)
$25=1000.000 (homing seek, mm/min)
$26=25 (homing debounce, msec)
$27=5.000 (homing pull-off, mm)
$100=40 or 20 (x, step/mm)
$101=40 or 20 (y, step/mm)
$102=40 or 20 (z, step/mm)
$110=5000.000 (x max rate, mm/min)
$111=5000.000 (y max rate, mm/min)
$112=5000.000 (z max rate, mm/min)
$120=400.000 (x accel, mm/sec^2)
$121=400.000 (y accel, mm/sec^2)
$122=400.000 (z accel, mm/sec^2)
$130=425.000 (x max travel, mm)
$131=465.000 (y max travel, mm)
$132=80.000 (z max travel, mm)​

I hope this is helpful (and accurate!)…