There are a lot of mistakes from my point of view:
bed screw knobs to position the bottom of the plastic knobs to 9-10 mm away from bottom of metal bed plate above
Distance is still same, if you leave 3 threads or 8 threads at the bottom of knob as example. Only change is in threads count, not distance to the metal plate! It's still same. In mine it's about 10.8mm. You should measure, (I'am not sure what), bot no distance to the plate. It's defined by knob height at all.
Next is when leaving front left knob alone. In my printer, even I do platform reset and set middle point to pass 0.15mm and use for the measure 0.15mm metal plate, then front left knob is too close to the bed. You must in first set front left knob and left all others alone. Only pres next, next next and do it again in same. Finally, then repeat procedure, but leave front left alone and set up three others.
After this procedure, it's repeated calibration steps and +- same result.
original setup steps:
4. Set Piezo Sensors to Reasonble Pre-tensionBefore doing any bed leveling, set bed screw knobs to position the bottom of the plastic knobs to 9-10 mm away from bottom of metal bed plate above. If your printer has just the locking nut (no lock washer), that leaves about three threads visible below lock nut. Once at this position, lock the front left screw in place. Leave that screw alone. Do bed leveling ONLY with the other three screws. That should keep you in good pre-tension range for all four piezos.
There are a lot of mistakes from my point of view:
bed screw knobs to position the bottom of the plastic knobs to 9-10 mm away from bottom of metal bed plate above
Distance is still same, if you leave 3 threads or 8 threads at the bottom of knob as example. Only change is in threads count, not distance to the metal plate! It's still same. In mine it's about 10.8mm. You should measure, (I'am not sure what), bot no distance to the plate. It's defined by knob height at all.
Next is when leaving front left knob alone. In my printer, even I do platform reset and set middle point to pass 0.15mm and use for the measure 0.15mm metal plate, then front left knob is too close to the bed. You must in first set front left knob and left all others alone. Only pres next, next next and do it again in same. Finally, then repeat procedure, but leave front left alone and set up three others.
After this procedure, it's repeated calibration steps and +- same result.
original setup steps:
4. Set Piezo Sensors to Reasonble Pre-tensionBefore doing any bed leveling, set bed screw knobs to position the bottom of the plastic knobs to 9-10 mm away from bottom of metal bed plate above. If your printer has just the locking nut (no lock washer), that leaves about three threads visible below lock nut. Once at this position, lock the front left screw in place. Leave that screw alone. Do bed leveling ONLY with the other three screws. That should keep you in good pre-tension range for all four piezos.