Re: BallNuts, 1,2 or a double.
Stuart,
I did this a while ago so trying to remember the exact figure. Around 0.05mm (50 microns) from memory based on a 16mm diameter 5mm pitch chinese ballscrew and single nut. Measured this using a DTI on the Y axis and jogging it from Mach3 back and forth in 0.01mm steps.
Re: BallNuts, 1,2 or a double.
I have a Chinese 12 mm ballscrew on my S7 cross slide, single nut and IIRC the backlash I measured when first installed was about 0.03 mm, 30 microns. My Novamill has about the same value using double nuts on 16mm screws, but that has had a lot more use! On a lathe it's nice to have low backlash if you want to do profile turning though would have to turn compensation on. I have tried compensation on the screws before but it doesn't work very well if the backlash is too large. In fact I found it didn't work at all!
Re: BallNuts, 1,2 or a double.
Thanks for the info on backlash amount's that you guys have experienced, always nice to have an idea of what is achievable.
With regard to the preloaded nuts (either springs or balls oversized) is their any rule of thumb for the added drag/resistance in the system?
Stuart