On Thu, 16 Feb 2017 11:23:44 -0700, "Bob La Londe"
wrote:

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.



Are you aware that the both the cars and rails are available with
either tapped or clearance mounting holes? See THK or IKO.

--
Ned Simmons