[TheForge] bar twisters

Wed Aug 27 13:06:02 2003

I'm not convinced:~)

You may only be stretching the extremities, and the centroid shall not
change, no matter how many revolutions.
Sounds like a good place for a test piece. But can we measure that small a
shrinkage?

dan tull
georgia
abba, afc, S.C. psba, obg,sofa
----- Original Message ----- 
From: "gladish" <[email protected]>
To: <[email protected]>
Sent: Wednesday, August 27, 2003 12:14 PM
Subject: RE: [TheForge] bar twisters

> >
> > Please explain how a solid piece shortens when twisted!
> >
> Hope you don't mind if I chime in on this one-
>
> Think about what's happening when you twist square stock- You're taking a
> piece of square, and in effect making it round. That is, if you gave it an
> "infinite" number of twists, say 100 to the inch, you'd end up with a
chunk
> of fairly round stock the same diameter as the corner-to-corner (not
> flat-to-flat) diameter of the square stock.
>
> My tables show 1" square weighing 3.4 lbs. per foot, and 1 5/16" (corner
to
> corner) round at about 4.6 lbs. per foot.
>
> Where does the extra bulk come from, if not shortening the bar?
>
> Of course, in real life the diameter of a highly twisted bar isn't as
great
> as the diagonal thickness of the starting stock- it's more of an average,
so
> the shrinkage isn't as noticeable as all that on most hot twists.
>
> Is that at least as clear as mud?
> Andy G.
>
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