Friday, 26 August 2011

LM8UU Linear bearings and T2.5 pulleys and belts

Ive also upgraded my system to use real LM8UU Linear bearings on all 3 Axis.

For this you need to print new x-carriage, x-end-idler and x-end-motor parts, and some LM8UU Holders to replace the bushings on the Y axis.

Currently all these things are in different places on the net.
LM8UU x-carriage is here in scad format
LM8UU x-end-idler and x-end-motor is here
LM8UU holders here

This is the underside of the new x-carrage.

This is the underside of my Y axis
This is the new x-end-idler
This is the new x-end-motor

In all of these I found the LM8UU holder to be very very tight, and inserting the LM8UU was difficult.

With the Y holders I broke several before I got a good set. I found that PLA is a little to brittle for these to be pressed into position and they just snapped. The best way I found to get these in was to reheat the holders in an oven to about 50c and then put the bearings in, while it was warm.

With the x-ends I put them in a vice and slowly squeezed it shut, forcing the bearings in.

One unexpected result of this upgrade is my commercial 11 tooth t5 pulleys was to large a diameter for the new x-end-motor. It physically fitted, but belt would rub on the lower stepper mount. The quick fix was to upgrade the belt and pulley to T2.5. These fitted without issue.

I then updated the Y pulley and belts to match

This image makes things look twisted, but they arent.

I got the t2.5 belts and pulleys from and


  1. Hey, nice work.

    I'm in chch and quite interested in building a rep rap, would be keen to come and have a look at yours if that's ok. I work at an engineering place so might be able to help you get a good price on stuff.


  2. @Euan I tend to have Reprap viewings on Sundays. Cant find anyway to send you a PM with any contact details.
    You can also find me on,68560 You can send a PM from there.

  3. Hello! What setup are you using for your idler pulleys? Just a 608 with washers, or...? I've got printed 608 bearing shells on my Prusa Mendel and they're coming apart.