Only sightly off subject

[p.cole@ntlworld.com]

Hi gang More than a few years ago, when I was at school, I remember being force to recite Mr Whitworth s formula that he devised for relating the diameter of one of his bolts to the A/F dimension of its corresponding nut. I can t for the life of me remember the formula now, nor can I find it in Machinery s Handbook or anywhere on the web. As best as I can remember it went something like: A/F = (O.D. x 1.25 + 1/8) inches. Thus the A/F dimension of a 5/16 bolt should be 0.3125 x 1.25 + 0.125, or 0.516 inches. This formula seems to get into the right ballpark each time, but modern practice seems to vary. Does anyone know why? Surely just because poor old Mr Whitworth turned his back somebody didn t get in there and fool around with it did they?

[Dave & Diana Dwyer]

When BSF threads were introduced, the finer thread meant that a given torque on the spanner would produce a greater tension in the fastener. To offset this, the spanner sizes were all stepped down by one: hence a spanner-end would be marked 1/4W 5/16BSF. If you can find an #OLD# 1/4W bolt or nut you will find that the AF is clearly bigger than on a 1/4BSF. I think from about post-war the hex on Whitworth was reduced to the same size as on BSF, and many years later the practice of dual marking was also dropped. Regards Dave Dwyer J2, TA, TC

[Badger]

To whom: A Whitwhorth bolt is not whorth a whit whithout a whitwhorth whrench whith which to whrestle it. Thank you Badger

[Clifford Lockrow]

Badger... Your really need a wench to wrench a whitworth wrench!!!! BADGER wrote:

> To whom: > A Whitwhorth bolt is not whorth a whit whithout a whitwhorth whrench whith > which to whrestle it. > Thank you > Badger > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[Roger Furneaux]

Peter - there might well be a formula, but yours is not it! All BSW head A/F sizes are 1/16" less than the old original BSW heads (at least, up to 3/4 BSF) so your formula would have to give 0.600" for 5/16 Whit. (O/D x 1.52) + 0.125 gives the right result, and is nearly correct for other sizes, but not all. I think the old larger Whit sizes were discontinued during the WW II to save steel, but spanners (and wrenches!) used the dual size markings for many years after. Hexagonally TCRoger Peter Cole wrote:

>More than a few years ago, when I was at school, I remember being force to >recite Mr Whitworth s formula that he devised for relating the diameter of >one of his bolts to the A/F dimension of its corresponding nut. I can t >for the life of me remember the formula now, nor can I find it in >Machinery s Handbook or anywhere on the web. > >As best as I can remember it went something like: >A/F = (O.D. x 1.25 + 1/8) inches. > >Thus the A/F dimension of a 5/16 bolt should be 0.3125 x 1.25 + 0.125, or >0.516 inches. > >This formula seems to get into the right ballpark each time, but modern >practice seems to vary. Does anyone know why? Surely just because poor >old Mr Whitworth turned his back somebody didn t get in there and fool >around with it did they? > > > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >

[Non-text portions of this message have been removed]

[Sam Suklis]

Ahhh....Badger: Whitworths interchange with SAE wrenches in 32nds and 64ths. Best regards from the rainforest, Sam.

----- Original Message ----- From: "BADGER" mrbadger@cox.net> To: "MG-TABC" mg-tabc@yahoogroups.com> Sent: Monday, July 08, 2002 4:11 PM Subject: Re: [mg-tabc] Only sightly off subject > To whom: > A Whitwhorth bolt is not whorth a whit whithout a whitwhorth whrench whith > which to whrestle it. > Thank you > Badger > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > >