Re: [CAD_CAM_EDM_DRO] thermal expansion

At 07:14 AM 1/28/03 -0500, you wrote:

>The bottom line is:
>with fixed- fixed end bearings one end must be able
>to float axially a little.

Not so, consult oh say Techno Isel ball screw ref for comparisons of
mounting methods. They advise the most rigid IE best setup is duplexed
preloaded bearings on both ends, with fixed mounting of each set. If one
end floats, the screw carries compressive loads in one direction, which can
induce the screw to buckle, elastically or otherwise, and that causes
whipping.

>by a tensioned fixed mounting are absolutely huge
>even with a few degrees temperature rise.

Actually, you mean a few deg differential heating of screw and machine
base. But that's seldom a problem. First, they're in same environment and
neither is heated much let alone differently and second, a few deg
difference amounts to only millionths inch difference.

Regards, Hoyt McKagen


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