I am converting a Rong Fu mill to CNC and the use of a single ball screw nut unloaded is not my idea of accuracy. Does anyone have a good idea on how to make a antibacklash nut using two unloaded nuts.

I have looked at numerous websites and I have not found any good ideas.

Thanks in advance as this group has numerous good thinkers and this idea is bugging me. I am used to programming machines with glass scales and accuracies in the 0.1 mircon area for HIGH RELIABILITY AEROSPACE applications and I want a highly accurate machine for home shop use.:cheers:

Although I don't currently have any good plans for building your own preloaded nuts, I am going to recommend Moglice. It's a great product, inexpensive, and gave me less than 0.002" backlash the first time I tried it. In theory, you can get less than 0.0005" backlash with it, but it might take a couple of tries.

HomeCNC has some plans for sale on his website (http://www.homecnc.info) I'm sure he'll be along later to fill you in.

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.