Easy Needle Bearing uses 1.75mm chopped filament

thingiverse

I wanted to replace a 608Z bearing with something more compact for a focus rail I'm designing. I wondered if I could make a needle style bearing using chopped raw filament, which would have the size and precision I need. This object is a prototype, but it appears to work ridiculously well and only adds 4mm to the height of the 8mm lead screw. (Half that of the 608Z). It should translate well to the focus rail project as this is a low speed, low mass, and likely low wear environment. It would be interesting to know how much speed, weight, and wear this design could tolerate; I suspect as is not a lot. However, when the bearing needs to be very small and load, speed and wear are not too high, it may be the only alternative to no bearing at all. In theory, to overcome these shortcomings, the concept could be extended with alternative materials like fibreglass rods as these come in various appropriate diameters, longer 'needles' and a thicker outer casing. Update: I've added a primitive rolling cage to remove the friction caused by the counter-rotation of the needles where they meet. There was little perceptible change. My guess is that the pins would have to be mounted axel like onto the cage, but this would be very hard to achieve in FDM.