Inconsistant filament driving

[Elaup 2]

Hi there!

 

I am suddenly experiencing under-extrusion with my UMO+ and I noticed that my feeder does not drive consistently the filament. When I rotate the wheel manually, I can feel that the resistance is not regular throughout the rotation, and the filament moves on and stops several times in one rotation. I tried to modify the pressure of the little wheel on the filament but it does not solve the issue.

 

Does someone had the same issue or know where this could come from?

[vincentbaas 19]

I don't have a direct solution (facing issues with my printer as well at the moment ;-) ), but maybe a step in the right direction: have you checked / cleaned the knurled bolt (the spiky thing grabbing the filament) and the feeder gear itself? 

[gr5 2,172]

Look for pieces of wood dust.  Find the assembly manual and look that over and take yours apart and look it over.  It could be many things.  Make sure the bearing rotates easily.  Spring should be compressed to about 10mm when feeder is closed up.

[Elaup 2]

Thank you guys for these advices! I will check these points. PLA dust was on the knurled bolt when removed it, so it could have come inside the bearing in the long run.

[Elaup 2]

Actually the bearing seems to be fine and to rotate smoothly. But the preset of the spring was really slight compared to what's recommended. I may have loosen the screw because of the plastic dust I was seeing when removing the wheel. This too slight pressure on the filament may have worn it without making it advance. Now I tightened the spring screw my material supply seems to be back to normal! Thanks a lot for your precious advices, as always!

[gr5 2,172]

As a quick test - the UMO can pull about 10 pounds (5kg) of force.  If it is pulling less than 5 pounds (2kg) it needs tweaking.  Set the filament in the bowden so it is about half way.  Hold the big gear in one hand and try to pull the filament out with the other.  Also try lifting something of known and similar weight (like a few liters of water) for comparison.  For example your printer should be able to "lift itself" meaning the force it can pull on the filament should be greater than the weight of the printer.

[gr5 2,172]

In this photo of PLA the tension on the feeder was too low for the pattern on the left and a bit too high for the pattern on the right.

 

 

[Elaup 2]

Thank you for these explanations! That's good to know even if I don't intend to use my printer as a lift...