[HomeCNC]

I have taken two ball nuts and made the ability to pre-load two wave washers against the nuts to get pressure seperating them on the screw. This is how the purchased ones work. I did this because of the price of the pre-loaded ball nuts are aroung $160 each from Reed Tool or McMaster Carr. You can get single nuts for $23 each and build the parts between to make the same thing.

Remember that the nuts are only ONE part of removing backlash. You can get backlash built-up from linear movement of the screw as well.