Re: [CAD_CAM_EDM_DRO] thermal expansion

Best to read the old thread...and again
"Precision Machine Design" has a good section on the subject
as well.

Les

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.alltel.net/~leswatts/wattsfurniturewp.html
engineering page:
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Surplus cnc for sale:
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----- Original Message -----
From: "Hoyt McKagen" <bjammin@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, January 28, 2003 7:20 AM
Subject: 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
>
>