Refurbing / Repair advice on UM2+

[gdog 4]

Hello - First time here, someone on r/ultimaker suggested coming here for advice.  I recently acquired a used non-working UM2+ as a library cast-off.  If nothing else, as I am probably one of a small handful of library users who regularly printed stuff on this machine -- mostly household repair parts for my personal use -- I figured I would poke around and see if I could get it working again. 

 

As the librarian explained it, the machine started to mess up prints by shifting the print in the x-y plane as it was being built up in the z-axis.  I'm not sure if it was a gradual shift (i.e., leaning tower of Pisa) or it is was just shifitng the position of a level and breaking the job.  Librarian suspected a problem with the x-y motors, although it would seem odd for both x and y motors to break a gear at the same time.  The suggestion I got from reddit was belts slipping and need to be re-tensioned.  Currently looking for a way to print the alignment sticks to hold the rods in place while tension the drive gears....  but would be great to know what others here think.

 

Also, I can't really see the problem for myself because when I started to examine the hot end, it appears to be completely FUBAR'd.  I plan to make a seperate thread about those issues, because it's just too much detail and what I'd really like at this point is some help assessing if this "xy shift" is likely to be an expensive fix (like replacing drive motors and stop sensors), or if perhaps it's not even an alignment issue but a bad calibration or a loose set screw causing the drive gears to move on the shaft (or some grease on the sharf under the drive-gear where grease probably shouldn't go.

 

All input is much appreciated!

[IRobertI 521]

The belts do not need to be tensioned by you (except for the short belts on the motors if you ever remove those). The long belts are tensioned automatically by springs in the sliding blocks.

 

More than likely the shifting is caused by a loose set screw which is a five minute fix. Take a look here:
https://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#shifted

 

You can start by checking the set screws of the pulleys in the top corners of the printer which are easy to get at and then do a test print. If it doesn't shift any more you're done. If it does shift, you'll need to check the set screws of the pulleys that are mounted on the motors and for that you'll likely need to remove the motors to get to the screws as it's a tight squeeze in there.

[Dim3nsioneer 558]

On 1/15/2022 at 6:57 PM, IRobertI said:

The belts do not need to be tensioned by you (except for the short belts on the motors if you ever remove those). The long belts are tensioned automatically by springs in the sliding blocks.

Though one should allow those springs to tension the whole belt and not just the half that goes through the sliding block from time to time: https://ultimakernasupport.zendesk.com/hc/en-us/articles/115004168883-My-Long-Belt-Is-Loose

[gdog 4]

4 hours ago, Dim3nsioneer said:

Though one should allow those springs to tension the whole belt and not just the half that goes through the sliding block from time to time: https://ultimakernasupport.zendesk.com/hc/en-us/articles/115004168883-My-Long-Belt-Is-Loose

 

That makes sense.  Thanks for the tip.  Since I can't see those springs, I assume they are internal to the sliding block?

[IRobertI 521]

They are internal, yes.