Cutting depth is way off

Got a 3018 pro today and it’s cutting beautifully along the X & Y axis. The Z axis is always falling short.

As an example, I have drawn a 5mm cut in Easel to cut a 5mm thick piece of HDPE (Z axis zeroed at top of material) and it’s only cutting about 2.3mm.

Any clues as to what this could be happening?

If you jog 5mm on the Z axis, does it actually move 5mm?

no, just checked. Jogged 10mm and it only moved around 4mm

ok, it seemed my $102 was set at a different rate to my $100 & $101. Now all set at 800 and it seems to be better

The travel of any axis is primarely governed by three factors:

  • Physical travel per stepper motor revolution. Screws, belts etc can give different travel per revolution.
  • Stepper driver resolution setting (Microsteps) One common setting is 1/8 step, each of the stepper native steps are divided into increments of 8. If set to 1/4th travel double vs 1/8th.
  • Step/mm value (GRBL $102 parameter for Z)

You can not edit the first factor, unless you chance screw type, pulley diameters etc
You can edit microstep setting, done by dip switches on the stepper driver itself. Use as little microstep, just enough so the 3018 move smoothly, too fine step level will have an impact on available torque
You can edit GRBL parameters, but I recommend finding your optimum microstep setting first, then recalibrate step/mm.