I have a problem most likely very similar to some reported by other users: extruder stepper is visually skipping a step from time to time. It rapidly rotates in the direction opposite to the one it is supposed to rotate.
I noticed the following:
- The extruder stepper jumps totally randomly - there is nothing specific in the pattern printed, position etc.
- Stepper jumps more often on the infill, rarely on the walls.
Details about print:
- PLA (Devil Design - various colors, they doesn't matter)
- Filament guide installed on top, but not yet before the extruder (it is printing right now, I'm waiting for the ball bearings too)
- Filament mounted on the top - in the place defined by Creality
- Extruder is already replaced with the aluminium one
- The mainboard is SKR E3 mini V2 (replaced recently)
- 95% flow set in Cura
- Printing on glass, leveled bed (the jumping occurs on all layers, not only first)
- 215 °C hotend temperature, 60 °C bed temperature
- Stepper motor current settings (from Marlin menu): 580 for X, Y & Z, 650 for E1
- What's interesting is that extruder motor jumps even if I manually unwind some filament, so that the only force that it has to overcome is only pushing filament into the head.
- I did a quick DIY wooden spool holder, so that the filament was fed almost horizontally. This actually seemed to make things worse - stepper jumped more often. I moved spool to the top again and it reduced jumping a little.
- Prints are done beatifully (after changing the motherboard, that is) - no lost lines or layers, walls connected with infill, perfect first layer etc.
What may be the cause of stepper motor jumping? How can I solve it? Does it pose a threat to the motor or stepper? I need to print filament guide and spool holder with ball bearings, so that I can minimize force required by the extruder motor, but then the stepper will probably jump during the prints. I already damaged the original mainboard because of stuck filament, I don't want to destroy another one.
This is how regular extruder retraction looks:(10 seconds)
This is how stepper skipping looks:(13 seconds)
Today I replaced the whole heat block (radiator, heater, thermistor and nozzle) to a new one (original, for now) and motor stopped skipping - at least on the calibration cube. I will see, how will it perform on more complex prints.
However, even having the prior one in hands, I couldn't find the reason, why motor was skipping - other than the fact, that I couldn't extract the bowden tube from the radiator (so maybe some filament indeed was dripping inside?)