Re: re:Final leadscrew design - thanks to all (not yet?!?!)

Hugh,

Looked at the .jpg . Not quite. Remove the spacer between the
bearings. Increase the thickness of the "step" opposite the retaining
plate(on the mount block).

The spacer between the nut and inner bearing race is not what I
described, but IS ok. Just "eats up" some leadscrew length, and
increases the "moment" of the part of the screw which is driven.

>So, if the bearings are "face ground angular contact pair" they are
>made to be correctly pre-loaded when forced face to face? i.e. no
>slop.

Correct.

>How about the "double row ball bearings" or "double row angular
>contact bearings". Are these built with a pre-load so there is no
>slop or simply to take more load than a single row?

These are made both ways. More common is NON-preloaded, to handle
more load as you suspected.

Those built with a pre-load are specialised and VERY expensive. One
exception is the bearing which is part of the Bishop-Wisecarver Dual-
Vee linear bearing system. This is a double row, pre-loaded bearing
with an outer race designed to be rolled on the B-W track. Very
fairly priced. I have used these in leadscrew apps where space is at
a premium, but prefer the 2 radial bearing trick.

Hope this helps.

Ballendo

P.S. The only difference between a fixed and rigid mount is the space
between the bearings, which requires spacers between the inner AND
outer races. Also requires a thicker mount block.