Extruder troubles: Filament feeder keeps jumping back

[SusisStrolch]

Do we need the 1.05V ref only for the extruder stepper driver?
Or should X/Y/Z also set to 1.05 (mine showed ~0.75 on all four stepper drivers)

[maddin]

As long as you don’t have issues with the axis drivers, just stick with the default values. The preset (and measured) voltage refers to a certain motor current, which translates to a certain torque. The relationship is explained in the motor controller datasheet. If it ain’t broken, don’t fix it.

[edit:typos]

[ivan.gkzd]

@maddin

Hi riodoro1,

thanks for answering. Meanwhile, I have fixed the printer (the feeder and a few other flaws) and it’s working fine now.
You are right, the issue is caused by insufficient motor torque or too much sliding friction on the way to the nozzle respectively.
First thing I tried was increasing the motor current and hence its torque. That helped a little, but after 20 minutes of printing, the motor driver got too hot and its thermal protection kicked in, limiting the current. The problem was worse than before.
I then took a closer look at the cold end. The motor shaft was quite hot and so was the wheel attached to it. Friction between the feeder wheel and the filament was significantly reduced by the heat. I disassembled the cold end and found the filament path to be roughened by the filament. The cold end is very liable to wear.

Solution: I replaced the original plastic cold end by a metal one and glued heatsinks (thermal glue needed!) to the motor driver ICs. I also replaced the crappy and loud cooling fan by a better one.

That did the trick.

Thank for feedback. Its a life saver. Where did you get new feeder? Can you post a picture of metal cold end?

thanx