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Prusa i3 Rod-Mounted X Tensioner

by thinkyhead, published

Prusa i3 Rod-Mounted X Tensioner by thinkyhead Apr 13, 2013

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[2014-11-20] Try Prusa i3 Add-On X Tensioner instead!

This is a simple adjustable belt tensioner that mounts on the top rod on the right end of the X gantry.

See it in action...


For an adjustable tensioner you need to add a 624 bearing, a 4mm screw, and a 3mm screw to this part. It's designed for mounting on the top rod on the right end of the X gantry. Of course your x axis needs to be set up so the bottom span of the belt attaches to the x carriage. This tensioner will probably work fine inverted on the bottom rod too.

The parametric SCAD file also allows you to print a non-adjustable part at your adjusted tension. A sample non-adjustable one is included in this Thing. You can also adjust other parameters, such as wall thickness, bearing screw size, etc.

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Really interesting. Not to say...smart!

Thanks! I liked this approach better than sticking a spring-tensioner on the belt or printing a whole new X-idler part. Of course now I'm using http://www.thingiverse.com/thing:554719 on my i3, but these little things are great for any printer where belts come close to the rods.

Prusa i3 Add-On X Tensioner

Very nice simple design! I've been using this for awhile now and it's been reliable. Also, I didn't have a 624 bearing when I originally made this, so I designed a 3d printable replacement.

Nice! That's a new idea. Should work ok as long as it's nice and round. I've switched to using my "add-on x-tensioner" on my i3 but I'd still use this design on any machine that didn't have an easy way to add a tensioner to the end.

Yeah I've ended up not buying any real bearings because the plastic ones I made have been surprisingly reliable. Didnt even use any lubrication or anything. I may switch to the design you mentioned simply for the sake of change and keeping things fresh, but thus far I've really had no need to.

Nov 9, 2015 - Modified Nov 9, 2015
thinkyhead - in reply to PazmanianDevil0

I'm in the same boat with my printed bushings. They work so well I don't think I'll ever need to go back to LM8UU bearings or Igus bushings. That's 10 more parts (on an i3) that can be printed instead of sourced!

When I slice this there is a gap where the screw hole is. Any tips?

What slicers have you tried? It seems fine for me using Slic3r