[modeleng] Re: Unknown Thread
- From: "georgecoles" <georgecoles@xxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Fri, 15 Oct 2004 14:54:30 +0100
My wife has just plonked "Machinery's Screw Thread Book" (11th Edition,
published 1941) on my lap. It was published by The Machinery Publishing Co.
Ltd. of Euston Rd NW1 (War address: 17 Marine Parade, Brighton 1. 'Frying pans
and Fires ?)
On the first page of the section on 'British association Thread' after some
preamble, and a defining drawing, the following appears:
Designation:- B.A. : sometimes the Swiss or Thury thread on which the B.A.
system is based. In the Swiss prototype the thread was rounded off at the top
and bottom of the triangle by a radius equal to 1/6 p at the top and 1/5 p at
the bottom, whereas in the B.A. thread the top and bottom of the threads are
both rounded to the same radius, viz. 2/11 p.
I don't even remember having this book, which has a myriad of screw threads
systems defined therein, including 'The Progress System' for watch screws,
which originated in Switzerland, is based upon the Thury thread, but has a
thread angle of 50 degrees.
I don't know if a scan, inserted rather than attached, would work on this list,
but I'll try if anyone wants the BA or any other thread diagram.
George Coles
Lurking and learning.
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