UMO with "jerky" motion

[trevox 0]

Hi!

I have a UMO that is 5 years old by now. After not having used it for a while, I started it again today.

It behaves as usual for a while, maybe a layer or two, then it start behaving extremely weird.

The steppers motors randomly stop for a fraction of a second before starting again, creating huge offsets in the print.

 

When I stop the print, I can hear the stepper motors making "knocking" sounds as if that stopping behaviour is still active.

 

Please have a look at videos here: https://www.dropbox.com/sh/uchybg5w90g0x28/AAC-gMREDlmU-HKnsFPo_9DMa?dl=0

 

Why is this happening?

 

Thanks for your help!

[trevox 0]

No one? :/

[moschidreamer 0]

Cable break? Connection? Stepps lost because of sticking guidance? Check how easy axis movment is withour motor, or turn motor when off. Turn motor on while move and try to get it hold by fingers to feel how much torque motor has. Apply the same torque when motor off, and feel if guidances are free easy move.

Edited March 6, 2019 by moschidreamer

[peggyb 169]

Just an idea: can you check if your fan at the bottom is running? I have seen something like this before, loosing steps in the first few layers, a wire of the fan broke off.