1605 Ballnut Floating Coupling

thingiverse

This is a simple Oldham coupling to eliminate the runout effect from low cost 1605 ballscrews when used for a 3d printer z axis. I have been converting a Leapfrog Creatr and found that the ballscrews were causing a lot of z wobble so this is my solution. This will de-couple the ballscrew nut from the bed and allow the nut to float without allowing it to rotate. It does require that the bed is constrained to vertical motion by means of rails or some other system. I have seen other designs that use ball bearings and magnets but I have my doubts about them due to rotational float which would cause imprecise z movement. The complete assembly requires 2 main bodies, 1 centre disc and 4 magnets to hold it all together and ensure the bed isn't relying solely on gravity when descending. I printed mine in ABS with quite a tight fit and then shaved the drive dogs down with a scraper to create a smooth and precise fit with no play. The mounting holes are simply tapped to suit the requirement for mounting, in my case I used M4. Support is needed for the centre disc only.