I have a problem most likely similar to some reported by other users: the extruder stepper is visually skipping a step occasionally. It rapidly rotates in the direction opposite to the one it is supposed to turn.
I noticed the following:
- The extruder stepper jumps randomly - 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 don'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
- The 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 the extruder motor jumps even if I manually unwind some filament, so the only force it has to overcome is pushing filament into the head.
- I made a quick DIY wooden spool holder to feed the filament almost horizontally. This seemed to make things worse - stepper jumped more often. I moved the spool to the top again, reducing jumping a little.
- Prints are done beautifully (after changing the motherboard) - 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 the filament guide and spool holder with ball bearings to minimize the force required by the extruder motor, but then the stepper will probably jump during the prints. I already damaged the original mainboard because of the stuck filament, and 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 the 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 the motor was skipping - other than the fact, that I couldn't extract the bowden tube from the radiator (so maybe some filament was dripping inside?)