Re: Re:- Ball Screw mounting block

Mike Gann wrote:
How is the pre-load determined?
Is this based on a spec from the bearing?
Thanks for your input.

Mike,

Not sure what you're asking here. How is the amount of pre-load
necessary determined? or... How is the desired pre-load achieved?

2nd question first. By adjusting the relationship between the bore
depth(s)and spacer width in the case of a RIGID mount; and by the
manufacturer in the case of a ground face, matched pair (FIXED type).

To determine the amount of pre-load necessary is an engineering calc,
(based on ball/race hardness, size of balls/rollers and expected
loads) and yes, you can get this info from bearing mfrs. Also check
out the book MACHINE DESIGN, or any of a number of other similar
books.

You can empirically determine correct pre-load for your use, and if
you are careful, not waste a set of bearings in the process. Roland
Friestad has written about this as it relates to spindle bearings on
mill/drills. He is a member of this list. Roland, are you there?

Basically you try a setting and watch bearing heating and check for
"play" in your usage. Then correct and repeat.

Ballendo

P.S. You CAN "fake" a fixed style mount with 2 radial bearings with
shim washers between.(a few thou thick to take out the end play).
Load capacity is not nearly that of ground face matched pair, but
cost is not nearly that,either :-)