Originally Posted by
HimyKabibble
Six thou of backash is pretty typical for rolled screws and nuts. With double nuts, the amount of backlash with no preload is totally irrelevent, within reasonable limits. Set the pre-load as loose as you can, and use a drill or something the run them end-to-end for a while. I think you'll find they loosen up, and get a lot smoother and quieter, pretty quickly. I assume these are black? The black coating is rough, but will wear down pretty quickly, making things a lot smoother and quieter. Once they're smoothed out, flush them out thoroughly, and re-oil them.
BTW - You shouldn't use grease on ballscrews - only oil. Grease will collect a lot more crud that can jam up the balls. A good thick oil, like way oil is good.
Regards,
Ray L.