How to pre load screws

[JAZZCNC]

Using C5 screws doesn't mean or guarantee zero backlash it's just the quality of the screw and accuracy over a given distance is better.!
Ball Screws are usually measured for accuracy over a set distance IE: 0.001mm over 300mm. The higher the accuracy over longer the distance the more they tend to cost.
The better quality C5 and above screws are nearly always ground screws has where C7 and low quality C5 tend to be rolled screws.
C5 and above ground screws are at best expensive, upto the point of obscene for C1 high accuracy. £1000's not £100's.!!

Notice I never mention zero backlash because true zero C5 & C7 rolled screws don't really exist off the shelf.? People make them or force them to be near has damn zero by trickery using using 2 ballnuts back to back with Belleville spring washers forcing them to preload against the screw.! . . This works but can if over done wear the screw and nut's prematurely.!
Double nut preloaded ballscrews can be bought of the shelf and use various ways like adjustable collars or shims, tough these are not always true zero backlash just very close.!

Robin and Jonathan have played with Belleville washers and C7 double nuts so search or check there posts but I think you'll find the Belleville washer the easiest method.?

If not wanting to DIY then be prepared to spend BIG BIG money for true Zero backlash C5 screws.!!