Doing some small inlays in mother of pearl - but it’s making small divots where the tool changes depth. Anything I can do about this?
Tool marks on plunge/retract point come from tool deflection and/or not true perpendicular Z-axis relative to X/Y.
After some thought, if it was from non perpendiculararity (is that a word?) why would it stick out instead of just the rest of the cut being as far off as the plunge cut? Hope that makes sense.
I slowed the plunge speed and raised the tool rotation speed and slowed the movement down. I have about 3/8" of the 1/32nd bit sticking out, I’ll try just leaving much less sticking out since my material is only .060" thick.
What is your step idle delay? If the stepper motor is not kept in position but released after a movement it may pick up the next full step value, this may cause a different position when it continues to move. You will be surprised how accurate your eye can spot a very small height difference which you can hardly measure.
This will cause your stepper driver and motor to be under power the whole time so you need to monitor the temperature.
From the library:
$1 - Step idle delay, msec
Every time your steppers complete a motion and come to a stop, Grbl will delay disabling the steppers by this value. OR, you can always keep your axes enabled (powered so as to hold position) by setting this value to the maximum 255 milliseconds. Again, just to repeat, you can keep all axes always enabled by setting $1=255.
The stepper idle lock time is the time length Grbl will keep the steppers locked before disabling. Depending on the system, you can set this to zero and disable it. On others, you may need 25-50 milliseconds to make sure your axes come to a complete stop before disabling. This is to help account for machine motors that do not like to be left on for long periods of time without doing something. Also, keep in mind that some stepper drivers don’t remember which micro step they stopped on, so when you re-enable, you may witness some ‘lost’ steps due to this. In this case, just keep your steppers enabled via $1=255.
It doesn’t take much for the tooling mark to appear so any minute “non-perpendicularity” may manifest itself while not showing much during during X/Y movement. However I am pretty sure you experience it mainly due to deflection.
Addition - tool deflection is one part of the equation, material deflection may also apply.