Re: [CAD_CAM_EDM_DRO] Sizing a Ballscrew ( was Re: Price of the ballscrew??

In a message dated 3/1/2003 9:35:15 AM Central Standard Time,
davemucha@... writes:

> I found the beam deflection file, is there a screw-sizing
> calculation ? after it gets so long it will sag under it's own
> weight. and if it is too small it will bend when pushed.
>

The BSA catalog gives extensive data and formulæ on calculating
screw-diameter for length and max. expected RPM. Just sag alone is not so
much a problem! It is when you ROTATE a long screw rapidly (say, over 600
RPM for 10' screw?), you can get into problems! There are different
bearing-configurations with different names like "unsupported",
"single-supported", "double-supported", and "double-fixed" and such (I forget
details now, and am too lazy to look for catalogs!). For an 8' table, you
will probably need at least 1¼" dia screws, if not 1½" dia., unless you will
be rotating them no more than 300 or 400 RPM. I know! I built a 5'x10' CNC
table for an English firm, and "did the math", and it WAS a project!

I just saved you the Google-hassle! Try this site, and see for yourself:
http://www.ballscrews.com





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