[TheForge] bar twisters

Wed Aug 27 19:03:03 2003

t i have made a few bars twisted each and every time it get fatter and shorter

Dan Tull wrote:

> 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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