Re: Fw: Z axis conversion

"F. de Beer" wrote:

> An other possibility is to split the gear of the quil pinion and make
> it a
> pre loaded one.
> Now you can drive the quill pinion shaft with a servo.

The problem with this is that none of these parts is a precision
component.
The rack teeth on the quill, the pinion gear, the pinion shaft, etc.
With a bakkscrew, you are pretty sure that you will get only a tiny bit
more backlash that the ballscrew itself has, and otherwide, the accuracy

will follow straight across from whatever accuracy the screw was made
with. With the rack and pinion, I wouldn't even guess what the error
might
be. Now, I do have a precision ballscrew in mine, and I've measured
backlash at about .0015", total, for the entire Z axis as a system.
Above
that, the accuracy is hard to measure, but it is better than .0002" over

the entire 4.5" travel, excluding the backlash (which I'd like to
improve).

I know you'll never do this well with the rack and pinion.

Jon