Quote:
Originally Posted by Railcarmover
Whitworth..
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While Whitworth generally follows the UNC/UNF thread TPI convention, the taps/dies themselves have a 55 degree included angle.
In my basement I have a circa 1860 Wood turning lathe made by one the early Worcester, MA machine tool builders (Likely Lathe & Morse or their predecessors.) The headstock bearing caps are threaded 7/16 -14 BSW - It was common for pre-Civil War American machine tool builders to "import" their tooling for threading.
A 7/16-14 UNC bolt will not screw into the hole more than about 8 turns.
I was tempted to drive a 7/16-14 tap into the hole to allow use of UNC dies to make the machine cut bolt - but I resisted opting instead for a $24.95 BSW die from Ebay.
Originality matter in historic machines. At least in my mind/wallet.
Joe K