I thought the same thing about that screw when I first priced it. Why so cheap? I assumed it was rolled vs ground?
It does have an odd lead value (about 0.201 inch/rev), but If my thinking is right, any inaccuracy caused by a difference in actual lead vs the lead that Turbocnc is given, would not be cumulative. Parts would be scaled up or down by a constant factor.
I have only checked the repeatablility of multiple movements over a 2" distance. It repeats within .001. I think I will check my accuracy by boring holes near each limit and checking hole locations on a CMM at work.
If my accuracy is off 0.0006 over (0.201x120) 24" I would be very happy. I probably have more inaccuracy due to the drill rod I am using for guides.
That screw vs an acme thread seems to me to be a good choice.
Bill |