Re: [CAD_CAM_EDM_DRO] Positioning

The specs on the screw accuracy are irrelevant.
What IS relevant is that there be no slop, as a machine with dual-feedback, ie glass scales, will shake itself to pieces is it has backlash.

Thats why you cannot use the crap chinese scales, because they are off, ie inaccurate, by upto 0.00" or 0.04 mm, in short distance, and the error varies.
So using such, would make the machine jitter (sometimes, in some places).

This causing back-and forth motion, upto hundreds of times a second, depending on how fast the secondary positoning error-correction mechanism is.

It is impossible to make a (working) secondary-feedback mechanism if you have backlash in the system.

Tony..
Unlike some people here, I try to be factual and polite.
Grin.

Re: screw accuracy.
Everything is inaccurate. Its just a question of how much.
One good part about glass scales, is that they are usually accurate (to 1 micron, or down to 0.01 micron with some Mori Seiki machines).

 

Sure, when you read the specs on the average screw, and that "Dummies Guide To Fantasy Machining" you've got.

Do you know what a drunken thread is?

Do you know what a temperature coefficient is? (Go work out the expansion on a 600mm steel screw for a 1 degree delta.)

Tony

(You and your microns, lol)

-- 
-hanermo (cnc designs)