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1/2" x 22tpi tap ?

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Andrew Tinsley18/03/2021 15:22:23
1817 forum posts
2 photos

Just sorting out some taps and came across an LAL 1/2" x 22 TPI tap. As far as I know, this isn't a standard Whitworth size, although Tracy Tools do list them.

Is it some kind of Whitworth special and if so what for?

Andrew.

Edited By Andrew Tinsley on 18/03/2021 15:23:38

old mart18/03/2021 15:35:09
4655 forum posts
304 photos

At the museum, we have been left toolboxes often over the years and I have a tin with all the special taps in it. From buttress tap sets to 40 tpi micrometer pitch and everything in between. Tap manufacturere will produce any size and pitch to drawing and they usually end up in a toolmakers box and surface many years later. Amongst the specials are pre plating sizes with + 0.003" or similar, they need to be kept well apart, or binned in case they get mistaken for standard sizes.

Howard Lewis18/03/2021 15:41:34
7227 forum posts
21 photos

Sounds like a special, since the normal 22 tpi Whit form is 5/16 diameter.

Tool small a diameter for a direct focussing thread in something optical, so more likely to give a fine linear adjustment..

Possibly for a nozzle capniut on an injector for an old stationary diesel engine, such as a Ruston Hornsby or a Fowler?

Just wild guesses

Howard

Oily Rag18/03/2021 20:17:46
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550 forum posts
190 photos

Think this was an 'Enots' thread standard. Probably used on sleeve nuts - so you could be close there Howard!

peak418/03/2021 22:07:30
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2207 forum posts
210 photos

I've not looked very hard, but did find a reference from someone on a Ford Model T forum, who was looking for a tap that size to repair a mechanical oiler.
Complete with photos towards the end of the post, and yes it looks to be for sleeve nuts
http://www.mtfca.com/discus/messages/29/49804.html?1205866146

Bill

Oily Rag18/03/2021 22:39:34
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550 forum posts
190 photos

Enots made pneumatic and hydraulic fittings and were used regularly in the M/C tool industry and in automotive. They were a company based IIRC in Birmingham and the name was Stones - hence the trade name of Enots was Stone 'arris about face! Now owned by Norgren and based in Liverpool.

It was always annoying using their stuff as the threads were specials and then also mixed in with BSP - so you might get something like a 1/8" BSP male to Enots female 1/4" 'special' which was from memory a 22tpi thread also. Apparently the reason given for the 'Enot standard' was the confusion that the BSP thread size was related to the pipe size not the thread size and Enots thought they would rewrite the book on this and hence make the thread size the actual thread size!

Edited for incorrect use of There/Their!

Edited By Oily Rag on 18/03/2021 22:41:08

Howard Lewis19/03/2021 07:14:15
7227 forum posts
21 photos

Thank You.

Shall bear that in mind, if ever I need to work on anything withan Enots fitting.

Howard

Pete Rimmer03/02/2023 17:56:33
1486 forum posts
105 photos

Andrew, do you still have this tap? My friend called me today wanting to chase out a 1/2"-22 thread on an old DSG lathe he's restoring. It's a thread for a detent plunger.

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