- Put calibration card under nozzle
- Set Z height to proper friction point where card will just begin to buckle when pushed.
- Set jog height to 0.01mm custom increment in Luban
- Jog up until loss of friction
- Jog down until friction restored
- Jog up, counting steps, until loss of friction
In 6) if you jogged up 2 steps until a loss of friction on the card then your backlash is 0.02mm.
Notes:
- The above procedure can be optimized, but ensures that the measurement is taken in an up direction immediately following a downward motion, which is important.
- The minimum movement the machine will respond to is approximately 0.02mm. Successive 0.01mm movements will trigger motion approximately every other movement (at least in my experience).
- If your measured backlash is much more than 0.02mm that will result in software drift due to a firmware bug. Specified manufacturing tolerance is 0.02mm backlash. If you are much above that you have a hardware problem requiring mechanical fixes beyond software capability.
An alternate way to measure, which I have also tried, is to use a caliper to directly measure motion in Z. I have had issues with this, but it would be better to measure backlash over a longer movement, say 25mm, to eliminate possible influence from machine minimum motion restrictions.