UM2 Loose Front X-Axis Belt - solved

[garret-kelly 0]

I recently received my UM2, and the bottom of the front X-axis belt is very slack. It jumps around visibly while printing. Is there any procedure for equalizing the tension on the top and bottom of the belt?

 

It might be worth mentioning that the Y-axis rod had actually come out of the black boxes during transit, but only enough that it made the X-axis endstop switch miss the black box, thereby smashing the X-axis into the left side of the unit as it tried to home.

 

 

[IRobertI 520]

Loosen the set-screws on one of the pulleys that the belt runs over, that should let the belt equalize its tension. And of course re-tighten afterwards.

Am I reading it right that you've already fixed the second problem?

 

[garret-kelly 0]

Thanks, I'll give that a try. I'd read the same procedure elsewhere, but wanted to make sure it wasn't going to radically move one end of the gantry out of alignment.

Yes, I did manage to fix the other problem. The Y-axis rod had slipped out of the bottom of both the front and back rod retainers which resulted in the rear retainer canting slightly forward (less than 1mm). Unfortunately this was just enough to make it miss the limit switch, which led to a few painful moments of my clamouring for the off switch.

 

[IRobertI 520]

Good to hear you sorted the other problem out. Just to re-assure you in case it ever happens again, even though it sounds horrible when that happens it wont harm the printer.

 

[gr5 2,167]

That loud noise is sometimes called the "death rattle" but usually it is harmless although in your case I think the belt slipped a tooth. Not serious but you have to equalize tension.

 

[garret-kelly 0]

Just to follow up, I followed your instructions and it works perfectly now. Thanks!

 

[irfanz 0]

I have the same issue after about 10 prints. Untightened one of the set screws and the belt tension is back to normal. As reminded by IRobertI, the set screw needs to be re-tightened afterwards.