[modeleng] Re: coarse threads

Previously, I mis-spoke about using it for cutting
grooves in rifle barrels.  This machine would not do
it, but now the question arises, in my mind, at least,
is HOW are the correctly pitched groves, say one turn
in twelve inches, cut in the guides that control the
cutters that actually do the work?  Old timers carved
them into a cylinder of wood with chisels, following a
spirally wound string, but how now??

Al Messer
--- Alan Stepney <alan@xxxxxxxxxxxxxxxx> wrote:

> Very interesting, however, one thing is certain, I
> wont be trying to make 
> one of them.
> 
> I am gradually restoring an old lathe I bought a
> couple of years ago, and 
> although lack of time has limited the amount done so
> far, the other day I 
> did clean one part, to find a brass plate detailing
> changewheels for thread 
> cutting.
> The threads listed are:
> 1,2,3,4,5,6,7,8,9,10.11,12,14,16,18,19,20.28 tpi.
> Some are the usual ones I would have expected, but
> the others are unusual.
> I was wondering / hoping that the threads might have
> given a clue to the 
> purpose as it appears to have been built for a
> specific use, although thus 
> far it has been impossible to identify the maker
> thus far.
> 
> 
> Alan Stepney
> 
> http://www.alanstepney.info
> Model Engineering & steam engine information pages
> ----- Original Message ----- 
> From: "Edward Bean" ebme@xxxxxxxxxx
> [modeleng] Re: coarse threads
> 
> The
>
<http://www.vcalc.net/cu.htm>Curta<http://www.vcalc.net/cu.htm>
> 
> mechanical calculators of the 1950s,
> 
>  Edward Bean 
> 
> MODEL ENGINEERING DISCUSSION LIST.
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> 



 
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