this are my new design for a anti-backlash z-axis. If you’re using the autolevel fuction it is very nessecary, that there a no clearances in the spindels to avoid inhomogeneous layer thickness. At first i tried the china-anti backlash T8 spinde nuts, which composed of 2 parts and a spring. But the tensing of the two parts wasn’t strong enough, so there was no anti-backlash effect.
i tought, that the idea of the split spindle nut wasn't wrong, so i just took two of them per spindle. But one of them i've modified with slot holes, which offering the possibility to adjust the backlash to zero.
To manufacture these slot holes you ideally need a milling machine whith a round table, but i think it is also possible with a drill press, a machine vice and a file.
At the x-end idler, i've also added a belt tensoner and the motor end has an optional mount for a igus energy chain (E2.10.10.018) so look at my offset chain link:
Both parts are designed for IGUS rjmp-08 linear bearings. A *.step file, if you want to make some modifications is available to download
Have fun with your Prusa modification