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Jim Wilkins[_2_] Jim Wilkins[_2_] is offline
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Default Linear Way Saddle

"Bob La Londe" wrote in message
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I'm working on a mid size CNC mill with linear rails. I've got a
lot of it figured out including squaring it up as its built. The
goal is a mid size bed mill with very good acceleration to optimize
use of a high speed spindle. Hence linear ways (amoung other
things) for its construction. Sometimes though the simplest things
seem to hang me up.

Optimally for support the bearing blocks both on the top and bottom
of the saddle would be at the outside corners of the saddle, and the
saddle would be a similar size (in X&Y) to a dovetail saddle
relative to the machine. If this is the case the bearings blocks
over lap each other on opposite sides of the saddle making it
impractical at best to bolt on the bearings. If I make either
dimension longer so they do not overlap then I lose a lot of travel.
If I make either dimension between the blocks shorter for the same
purpose I lose more stability and support than I care to. The table
is modestly heavy and I do need to minimize sag from table weight.

The only solution I have come up with is to make the saddle out of
two pieces that are keyed for alignment and then bolted together
after the bearings are mounted to their respective halves.

I am hoping one of you guys will have a simpler more elegant
solution.


Thomson rod bearings have mounting flanges:
http://www.thomsonlinear.com/website...xtra_rigid.php

-jsw