![]() $130=299.000 $131=179.000 $132=44.000 set the XYZ travel limits relative to the Home switch trip points, which feed into the $20=1 Soft Limits. These are two orders of magnitude higher than the default acceleration, which accounts for the as-received sluggish acceleration. $120 $121 $122 = 3000 set the acceleration along the XYZ axes in mm/sec². I’ll have more to say about speed limits, stepper current, torque, and similar topics. Note the hard upper limit set by the maximum microcontroller interrupt rate of about 40 k/s: 1500 mm/min = 25 mm/s = (40×10³ step/s) / (1600 step/mm) $110 $111 $112 = 1100 set the maximum speed along the XYZ axes in mm/min. The Camtool V3.3 board hardwires the DRV8825 stepper controllers into 32 microstep mode, so: 1600 step/mm = (200 full step/rev) × (32 microstep/full step) / (4 mm/rev) This depends on the mechanics of the limit switches, but seems OK with the MBI-style switches I used: $27=1.000 sets the Pull-off distance from all three Home positions, so the machine ends up at absolute XYZ = -1.000 mm relative to the switch trip points after homing. $22=1 enables the Home cycle, after which you must start each session by homing the machine. $21=0 leaves Hard Limits off, because I didn’t see much point in switches on both ends of all the axes for this little bitty machine. $20=1 turns on Soft Limits, thereby producing an error when you (or the G-Code) tries to move beyond the machine’s limits, as defined by the $120 $121 $122 values relative to the Home switch positions. $3=5 reverses the X and Z motor rotation, so you can use the same type of cable on all three axes and have them move the way you’d expect. There’s no force worth mentioning on a diamond scribe when the motors stop, so there’s no reason to keep them energized, and the DRV8825 chips resume from the same microstep when re-enabled. ![]()
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