Ultimaker Belt Tensioner

by Gijs, published

Ultimaker Belt Tensioner by Gijs Mar 24, 2012
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Belt tensioner for the long belts. The wave shape is designed to minimize point stress as in other designs.


loosen pullies before installing, then realign the X and Y axis.
The belts for the Y axis are a bit more difficult to install than the X axis. It's important to put the open side pointing inwards, otherwise they will run against the sliding blocks.

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Thank you! Greatly improved the tension on my Prusia i3 x axis

This comment has been deleted.

These worked great on my i3, Thank You

printed two one for the back one for the front and it made a not so good noise

Basically you need to release one of the pullies for each belt before you can install them, otherwise you create more tension in one side of the belt. Have you done this?

dont have a clue how to do that

Are you sure that your belts aren't tight enough? Which ultimaker do you have and how old is it? On a newer ultimaker original I have, they are not necessary, neither on ultimaker 2.
If it's old and they need more tension, then just loosen the set screw in one pully with a hex screwdriver provided with your ultimaker, put the tensioner on and retighten the set screw.

I bought it second hand its the original

I recommend you go a bit through this page to see how the ultimaker is constructed:

see here if you need them at all:

theres lots of screws and i dont wana break the printer

you can't really break the printer. It's meant to be a maintainable printer. If however you are not confident, I'd recommend you find some fellow Ultimaker users in your neighbourhood to help you out. But it isn't really that difficult. If you read through the link I sent of the XY axes, you will see that it isn't that hard. It's only one screw you have to temporarily loosen per belt.

Theres like none in Ireland other than myself that has an ultimaker but I think I know what screw it is now

do you print 4 out 1 for each belt????

Put the belts back on strength, significantly increasing the print quality. Thanks a lot!

oh, that is a nice design...

Very nice looking design, but I couldn't get it to fit the 10-2012 Ultimaker. In the end these did the job: http://www.thingiverse.com/thing:17058http://www.thingiverse.com/thi... 
Hope this helps future users choose the right belt tensioner.

Ultimaker Belt Tension Clips

if you carefully insert these and make sure that the opening faces inward and that they are flush with the side of the belt, there should be no issues. The ones on the Y axes are facing upward in my setup and slightly touch the top wooden panel. But again this doesn't cause any issues.

I agree, I'd love the source for this one. I have bed adhesion problems, so I'd like one with a flat side, rather than the nicely chamfered edges, and I'd like to make the wave a bit deeper. I can recreate from scratch, but it would be a lot easier to fix this than recreate!!

What software do you use? I can post this as rhino file, step, iges.

If rhino, I can also post the source curves as well

I have Rhino, but I've mostly been using Autodesk's Inventor Fusion, so step is best, but by all means, share what you have! I'm sure others would like the Rhino, and I'll take a look at it if you post. :-)

I posted the Rhino file. I think it is better than posting the step file if you want to modify it, because you will need to modify the base curves. The posted Rhino file shows a step by step how I made the object.

Caution: These can rub against the sliding blocks (even inwards facing) and the Y ones axis against the top of the housing.

Yes, I have the same problem too. But with a little bit of trying I at least solved the problem with the sliding blocks- They are no longer touching the belt tensioners. But I have the same problem too with the Y-axis and the top of the housing. But I think that it is not a big problem as long as my prints do not become messed up.

Greez from Switzerland :)

This looks really nice! You're really producing some very nice parts!

Can you start posting source files with your stuff though? I always want to edit things and STL is terrible for that. I typically post my source file, an STL, and a portable format like STEP just so that no matter what software someone has, they can edit my files.

Love the simplicity of this.. I have been looking to get some slop cleaned up so I'll give it a try in ABS.. Thanks. :-D

Working very well for almost a month now, no noticeable differences :)

Is this really working with PLA? From my experience all designs are softening up over time and loose their main purpose.

Great looks nevertheless ;)

I used PLA and it worked great- I am printing with it for over a month.