MonthJanuary 2016

Z Axis setup for the Duo Cube

At the top the M8 threaded rod is mounted using an axial ball bearing, so it just hangs down from it.
At the lower end it goes through a radial bearing that is mounted from the bottom. The pulley is mounted in a way that the whole screw is tightened slightly, that way it never bends but will always be straight.
I use an axial bearing at the top since the load is the weight of the X assembly plus the tension on the screw, while at the bottom i only use a radial bearing since it mostly has to cope with the pull of the belt and in axial direction only with the tension force.

Z-Axis-01 Z-Axis-05 Z-Axis-04 Z-Axis-03 Z-Axis-02

Using Sinterbronce bearings

This popped up a couple of times on the reprap forum.

Often people ask what bearings to use and i am surprised how often the recommendation is LM8UU for linear bearings.

While LM8UU are cheap (at least the low quality ones) and easy to source, they come with some drawbacks. Ballbearings like LM8UU are designed to withstand rather high loads, much higher loads than are usually encountered when building 3D printer. They are also comparably loud and bulky.

For me sinterbronce bearings are a much preferable alternative for most cases.

They are cheap, even the quality stuff, they are silent, small and very easy to use.

Here are a few images on how i use them for linear motion.


x carriage

DSCN1033_small DSCN1032_small DSCN1029_small DSCN1028_small DSCN1024_small DSCN1022_small














As you can see i only use the rather thick walled variation, they don’t deform easily, which makes it much easier to use them.

The images show the use for the X carriage of my Duo Cube printer as well as the use for Z. Depending on load and available space i either use zip ties or counter plates to mount the bearings.

The rendering shows the shape of the mount. It only holds the bearing in the middle and stops it from leaving the mount. Other than that it can rotate rather easily, which makes it super easy to align the bearings.

I have been using this type of mount in various prototypes over the last year and never had any problems, on the contrary, the precision fit is first class, even the small X carriage has no noticable give at all, but runs smooth and easy.


LM8UU to Sleave bearing adaptor





If you want to replace a LM8UU linear ball bearing with it’s more silent, cheaper and less weighty sleave counter part 8x12x12 you canuse this adaptor.

I basically only use sleave bearing for all linear bearings nowadays and for quite a few radial bearing uses as well. The smaller formfactor alone is a huge argument for me.

LM8UU Adaptor


On Thingiverse

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