Belt tensioner

by Misguided, published

Belt tensioner by Misguided Jul 15, 2011

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After seeing the Ultimaker Belt Tensioner by psync (http://www.thingiverse.com/thing:10034), I decided to model my own that didn't need a screw. But of course there's also Roboteer's Paperclip belt tensioner (http://www.thingiverse.com/thing:4535)

Note: It's been mentioned in the comments that there isn't enough space between the new style Ultimaker slider blocks and the belts. Which causes the tensioner to hit the blocks.


Hook the tensioner onto the belt (as per the picture) in such a way that it won't interfere with movement.

If you need more tension, make the part thicker (or make the post width thicker). Need less tension, make the part thinner

If it's too difficult to hook on, make the part longer.

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Belt tensioner by Misguided is licensed under the Public Domain license.

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Works fine on the Velleman Vertex (K8400).

The simpler the better. Does the job perfectly!

WOW. This saved my printer. My printer would print fine on simple blocks and straight things, but whenever I tried to print something more complicated it would shift layers really bad. I tried to tighten my belts but I just couldn't get them any tighter. I printed this and put it on my Y belt and It fixed immediately.
Thanks so much for thinking of this! It saved me a lot of frustration.

HICTOP Prusa i3

No-Go in the latest Ultimaker revision...  (november 2012)

You have to max out an axis and place it on the opposite end bud, otherwise it will hit. It works on Ultimaker 1 and 2, as well as Grid2 and Replicator 1 and 2.

Did 4 of them some week ago, no problem!

I printed 4 of these for my ultimaker, and I ran into a problem. The new style slider blocks are so large that they hit these belt tensioners. So I had to take them out again.

That's a shame. How much clearance is there between the belt and the blocks?

I'll take a measurement later, but it depends on the X or the Y belts. I think the Y belts worked, while the left X belt hit the tensioner. It only scraped the corner, but enough to make the motor skip steps. (And with a loud enough noise for me to abort the print that instance)

I'll see if I can take a photo of the problem.

Daid - in reply to Daid

Forgot to take a photo, but there is like 2mm of clearance at max at the problem belt. It's the left belt for me that causes these problems. (if you look at the machine from the front)

I'm assuming that the problem should manifest on the right belt as well?

But 2mm isn't much room to play with... I'll have a think/play and see if I can come up with something.

My circles came out a bit oval the other day, having checked every other option the belt tention was the only thing I could fix. I tried fitting these again, and you can fit them, but you need to have them the other way around then the photo for the Y belts.

With that new position, is there still the issue with the tensioners hitting the new sliding blocks?

As long as the tensioners are placed with the middle post on the side of the belt facing the block I have room to spare, even on the Y axis.