Pulley motor stops turning mid-print?  

Re: Pulley motor stops turning mid-print?

Problem is known -> https://github.com/prusa3d/Prusa-Firmware/issues/1377

Re: Pulley motor stops turning mid-print?

I'm getting this same problem. But it's only happened to the pulley motor once. It usually happens to the idler selector motor. It just quits and i can easily turn it by hand. It happened once with both motors.

I'm running 3.5.1 and 1.0.3

Frustrating, as I thought I had finally gotten everything working correctly.

Re: Pulley motor stops turning mid-print?

You can recover the print by pressing the reset button on the mmu2 unit.

I had the same issue. After I updated the PTFE tube to 2.5 mm id it didn't happen again. And I printed about a week non-stop since then. Don't know if it is a coincidence.

Re: Pulley motor stops turning mid-print?

Also just started getting this issue with the latest firmware, never an issue before.

I will try the reset option next time

Re: Pulley motor stops turning mid-print?

where is the reset button? everyone keeps saying they reset but i cant find in the documentation or forums where or how to reset just the mmu

Re: Pulley motor stops turning mid-print?

where is the reset button? everyone keeps saying they reset but i cant find in the documentation or forums where or how to reset just the mmu

Next to the usb input on the MMU2 there is a hole. Just use some filament and push the button.

Re: Pulley motor stops turning mid-print?

OMG. I have finally fixed my terrible MMU2 experience. It was this issue all along.

I've spent hours adjusting resistance, aligning gears, adjusting spool positions, etc. but always my MMU2 would fail randomly. And when it failed I could never resume the print. The inability to resume should have tipped me off that I was having a different failure than most.

Finally I read this thread and the related github thread. Turns out I couldn't resume because my idler selector motor had gone limp. It was easily rotatable by hand. Having no other experience I thought this was a normal part of the process. Maybe to let you easily clear stuck filament or something. It is, in fact, not normal.

The root cause theory on the github thread is that vibrations during printing cause a connection to the motors to briefly disconnect. That seemed kind of crazy to me because of how securely all the connections are in place. However I can tell you that this was absolutely the case for my failures.

Inside the Einsy box the MMU2 signal cable does not have any latching. For me it seemed to make good contact but it could also be removed without much force. I decided to ever so slightly bend the pins on the Einsy so there was a tiny bit more horizontal pressure to hold the signal cable in place. In addition, I took the other cables that I had neatly routed to the sides of the box and just piled them on top of the signal cable (where they want to go naturally anyway). Now when I shut the Einsy box those other cables are squished a bit on top of the signal cable holding it more securely in place.

After doing this I have had no more "limp motor" failures. I've done some pretty big prints and everything works well. I've had the occasional retraction failure but after fixing the issue I've been able to resume the print.

So if you are having a failure with these symptoms I highly recommend firming up all connection to the MMU2 (in particular the signal cable) even if they seem perfectly secure.

Re: Pulley motor stops turning mid-print?

I wonder if this issue is the cause for the shipping delay?

Maybe they are swapping out the bad parts for new ones, and waiting on the supplier.

I can only hope (since mine hasn't shipped yet, Sept 3rd order date).