Y belt skew  

Active Member

The Y belt of my MK3S+ is skewed. It's touching one side of the pulley on the motor side, and the other side of the pulley on the idler side.

See here:

I've tried loosening the rods to rotate the carriage and tighten, I've tried loosening the motor and idler, move them and tighten, but I'm still there.

Next step is to try and move the linear bearings under the carriage, but this is quite cumbersome since the fasten with nuts that are difficult to access. So I'm fishing for ideas and advice. The printer says my XY skew is just below the "slight skew" limit.

I believe that the this belt skew is what is giving me ripples, see two benchies printed pointing one at a 45 degree angle, the other straight to the right:

Posted : 04/02/2021 11:17 am
Peter M
Prominent Member

Check if the whole printer is not aligned.


Try loosening the y belt, to much tightened is not good, the belt should have a little play to adjust wen moving.(same for x belt).


There is a movie on youtube about putting better rails on the mk3, 200 dollar upgrade, it printed worse then the stock.

https://www.youtube.com/user/ThomasSanladerer/videos    he has made the movie.

Posted : 04/02/2021 11:57 am
Active Member


Thanks for the reply!

I'm not sure what you mean with "the whole printer not aligned"?

I've now loosened the belt much, see here.

Then I tried to move the belt sideways on the pulley, and move the Y axis back and forth. The belt got slowly back to touching the side of the pulley, see here.


Posted : 04/02/2021 12:33 pm
Active Member

So, I flipped around the motor pulley, and I think I got rid of the ripples. Tested on a smaller print (a cylinder), going to print one more benchy (but I'll try to fix my extrusion first).

This post was modified 3 months ago by Gauthier
Posted : 04/02/2021 8:07 pm
Estimable Member


Good idea to flip the pulley.  I don't know why that didn't occur to me to try that on mine.  I will do that this weekend.  I had not noticed any rippling on my prints, but I'll look to see if this affects the quality one way or the other.  Thanks for sharing.

Posted : 05/02/2021 1:43 pm

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