Pulley Motor Stalls  

Pulley Motor Stalls

Hi,

I encounter the problem that the pulley motor stalls sometimes when retracting the filament from the extruder to the MMU.

Observations:

• My MMU has many modifications, but the pulley part is mostly unchanged.
• Initially, I used clone components, but I upgraded to the original pulley motor.
• After swaping the motor to the genuine part, it did ont happen for quite a while, now it happened 2 times within 2 days. (Maybe still random since I did not print very much after swapping)
• When a stall occurs, I can pull on the filament. After I overcome a resistance, the the motor rotates again and the MMU will continue operation.
• I recreated the stall when driving the motor with a standalone stepper motor driver. It happened above a certain speed (only when the the speed is beyond a certain thershold and each time when going beyond the threshold). It also happened when the motor was outside the MMU and nothing attached to it.
• My MMU is mounted outside of the printer enclosure. Its orientation is such that the pulley axis points up.
• Before upgrading to MMU3, I used the stealth mode to prevent stalls. I think the lower retraction speed is key.

Is there anyone who encountered this problem, too?

I mostly guess that I damaged both motors, but I am not sure how.

Do you have ideas for the reason? Maybe the orientation lead to higher wear in bearings? Or what else could damage the motor? Maybe the reason is something totally different?

Is there a way to set the retraction speed of the MMU?