odd threads

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odd threads

Post by mikechoochoo » Wed May 08, 2019 12:14 pm

I picked up some Little Giant threading dies at a flea market. There are a couple BSF sizes with them, not marked BSF but the diameter and tpi match. There are also a 13/16-10 and a 1 1/32-8. Another one is marked 7/16 1/32 14 ? I can't find these sizes listed anywhere and the 7/16 one has that odd 1/32 on it between the 7/16 and the 14. Any idea what machines might have used these thread sizes, or the meaning of the odd marking on the 7/16 one? By the way there is a "standard" 7/16- 14 die with them, looks the same except for the markings.
Anyway it's interesting to me learning about these obsolete and specialty threads.

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Re: odd threads

Post by SteveM » Wed May 08, 2019 1:39 pm

1-1/32x8 seems so close to 1x8 that it doesn't even seem worth the effort to make an oddball size, unless the express purpose was to make something nobody else would have.


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Re: odd threads

Post by spro » Wed May 08, 2019 5:39 pm

sounds like conventional sizes for iron pipe at That time. We think of tube and pipe having a standard inner diameter but it was certainly different measure then. Older Machinery's Handbook.

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Re: odd threads

Post by Rwilliams » Sun May 12, 2019 1:19 am

A century ago, threads were still not standardized real well. Many companies developed and used proprietary threads just insure you bought their parts if you needed spares for repairs. The singer sewing machine company was notorious for such activity. The Nathan Manufacturing Co often included some specialty threads for parts that would wear out on their injectors. Insured sales of spare parts unless the railroad had a good machinist with plenty of time to set up for the specialty thread. Today with Nathan long out of business, keeping the surviving Monitor injectors in good repair can be challenging to even the best of machinists. New old stock often exhibits slightly different pitch diameters which have to be checked and almost custom fitted as if one was building up a custom rifle.

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Re: odd threads

Post by NP317 » Sun May 12, 2019 10:01 am

As we are rebuilding the WAAAMuseum's ( http://www.waaamuseum.org ) 1901 Locomobile engine, we just tackled rebuilding the steam engine's mechanical water pump.
The bronze cast pump body has unique threads on each of the three openings! None are standard today.

Our solution is to machine adaptor fittings to fit each unique thread, with the other end threaded for today's standard commercial copper tube fittings.
This way we can easily maintain an operating vehicle, without altering the original pump casting.

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