UM 2 Belts grinding - I've noticed some black specks on the stepper motor case?

[francfalco 37]

Hi and a Happy New Year to all!

So I've been reading on a couple of resent threads about some UM2 having the issue of spacers/bearings being slightly out of align and causing belts to grind? I'd never heard of that before but looking at my machine, I've noticed some black specks on my stepper motor case as above (I always assumed it was normal dust?), but it may be this grinding belt issue?.

I havent noticed any effect in print quality but just wondering if:

1. Is it something that I should fix?

2. How can it be fixed?

3. What causes it?

Over to you guys.

Cheers

Franc

Edited January 8, 2016 by Guest

[shurik 87]

Hi,

Have the same story for a very long time. Really long, probably over a year now. So, it shouldn't be that bad, although it would be nice to get rid of that.

[SandervG 1,521]

The black specks are part of your belt, so it may not be urgent but you probably do want to take a look at it.

It is probably the belt rubbing against a rim or side of a pulley.

You can change this by either seeing if you can improve the alignment of the spacer, or replace the pulley slightly, maybe like a mm.

[francfalco 37]

The black specks are part of your belt, so it may not be urgent but you probably do want to take a look at it.

It is probably the belt rubbing against a rim or side of a pulley.

You can change this by either seeing if you can improve the alignment of the spacer, or replace the pulley slightly, maybe like a mm.

 

Hi SandervG,

Thanks for the update.

Have you any guidance/how to (video/blogs) on what i need to actually do to improve alignment of the spacer or align pulley please?

cheers

[Dim3nsioneer 557]

The rubbing of the belts against the pulleys comes from not well adapted lengths of the spacers between a pulley and the corresponding ball bearing. I printed myself some spacers with corrected lengths. Since then I could reduce the rubbing to a very tiny amount.

Just moving a pulley only leads to additional play of the corresponding axis as the pulleys fix the axis' position.

The black specks should be removed before a print with light filament. I found the fans blow them easily onto your print (standard fan duct).

[Morandir 3]

I too have been having the same issue.

By moving the print head and applying pressure to the belt from the side, I'm able to center the belts on the pulleys. It isn't a spacing issue as the pulleys have plenty of room for the belt. As the printer operates, the belt returns to it's grinding position against the side of the motor pulley.

Due to the natural return, my guess is that the axes of the two pulleys are out of parallel enough to have the belt walk against the pulley wall.

I too would appreciate some guidance on how to correct this issue, as I believe it may be contributing to my slight issue with gaps between the infill and the wall (the belts are tight, especially the short ones). My thought is maybe thin washers on one side of the motor to better align the axis, but as it's really tucked away in the corner, I haven't undertaken the effort.

Back over to you guys again.