Hello All,Can anyone enlighten a poor yank about threads in the size of 5/16-26TPI? This is called out for the piston gland nut on the Stuart Turnermodel 10V casting set I am currently working on.I have been trying to locate a tap and die for this size and havelooked within the BSW, BSF, and BA series of thread forms to noavail. Of course they are also not to be found in the american systemUNC or UNF types here. I have found most every other TPI but 26.I suppose I can always substitute the UNF 5/16-24 size, but I havebeen faithful in all other instructions for size of threads and suchwith this engine.This is one of two Stuart casting sets I inherited from my Dad, theother being a model 10H. The 10H had been started by him back inabout 1970, but is only about 1/3 complete. The 10V was stilluntouched in its original box. I know they are quite old sets now. Theprice listed on the included instructions for an unmachined set was 1+ 3/4 Purchase Tax. They cost a lot more now I see. I really do notwant to mess these up.My grand plan is to finish them both as a matched set. So far so good,but I'm not that far into it at all. Mostly focused now on planning,research, and gathering tools, and as I said, I still need to get onemore tap & die, 5/16-26. Any hints, or other help at all, would bemost welcome at this point. I know my questions must sound like I'm areal newbie, sorry bout that. I suppose most of you guys built yourfirst Stuart Double Ten at age 5, hooked it up to your Mum's teakettle, and hob-nailed it into a home-built cedar-strip launch forlazy summer cruises on the channel. ;-). Do be gentle.With kindest regards,Paul Schiller

Look for BSB (British Standard Brass) or BSC (British StandardCycle).Should get you what you need.Here`s a link to a page which has all the thread data.

5/16-26TPI Thread form?

Apr 07, 2009 22 Replies

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PaulS 17 years ago

Thank you for the very helpful link Jason. Yes, I understand what you're saying about the ME pitches. If I recall correctly, Guy Lautard of TMBR, lists 5/16-32 as the ME pitch for this size.

Best regards,

-- Paul Schiller PDA Panache Corp.

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gunsmith 17 years ago

A note for our friends over the pond. ME threads use a Whitworth form i.e. 55 degree.

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Steve R. 17 years ago

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In North America, why not just use 5/16-24 UNF/NF, or the harder to find

5/16-36 UNS/NS? The engine will look the same, and work just as well.

National Special (NS) threads include obsolete, and seldom used threads. Taps and dies are available, but sometimes have to be ordered from suppliers.

Steve R.

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