Re: Ballscrew Nut-blocks and Thrust bearings

In a message dated 08/27/1999 8:37:41 AM Hawaiian Standard Time,
timg@... writes:

<< Needle thrust bearings are about US$3.50 for the set of cage and
thrust washers from MSC.

Tim
[Denver, CO] >>
Tim,
Another possibility is to use Timken taper roller bearings. I was
supprised to find they come as small as 10 mm bores. Approx .3937". They will
hold up to thrust much better. I'm using thrust type ball bearings but am not
completely happy because they are difficult if not impossible to get with
shields or seals.
One note on using two nuts on an axis for preload. I bit the bullet and
got the twin preloaded nuts for the .631 X .200 screw. (Mainly because of
space restrictions.) They have a large wave washer between the two nuts. By
turning the preload ring nut, the amount of preload on the wave washer can be
adjusted. The instructions caution against turning the ring so much that the
wave washer is flattened. I believe that is so no large binding forces are
placed on the assembly if the lead varies too much from place to place in the
ballscrew's travel.

Peter
P T Engineering Co.