1 inch fine thread?

[Bob Bancroft]

My charts show 1 inch fine thread as 12 TPI. My die is also 12 TPI. Now it's appearing as if somewhere along the way 14 TPI has become the standard?

 

[Butch(OH)]

Coarse threads used to be called USS (United States Standard) are now also UNC, Unified Coarse. Fine threads used to be SAE (Society of Automotive Engineers) are now also UNF. All special non standard threads are designated UNS.
1"-8 is USS/UNC
1"-12 is SAE/UNF
1"-14 is UNS

 

[Bob Bancroft]

Interesting, thanks. I got into a bit of a pickle working on my Woods bush hog type mower. The manual showed the rotor/gearbox nut as metric. After much consternation, I discovered another page with a different gearbox, 1 inch 14 thread. The local industrial hardware had all types of 1-14 nuts, but not 12!

 

[Butch(OH)]

Well I'll be hanged, it so happens I had purchased a couple 1" grade 8 cap screws last month. Checked them and they are 14tpi. Hmm, guess somebody has decided that 14tpi is now the standard? My tap and dies set is 10 years old and the 1" are both 12TPI

 

[Watthour]

Wait until you get into shaft lock collars, bearing locknuts, and fixture nuts. Some of those are a lot finer than 14TPI. For example, an NI-03 bearing locknut is 1-16, and fixture nuts can be 20 TPI. Standards are for amateurs. Pitch gauges rule.

FWIW, 1-12 IS a standard UNF nut, so any real hardware store or industrial supplier should have them by the box.

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[timcasbolt]

I've seen 1"-16, and there is a 1"-6 in acme.

 

[Russ from MN]

We used to run into that at work, some equipment would be 12 tpi, some 14. We had to be careful to check them.

 

[bc]

I just run into a different issue with a rebuilt engine missing an oil galley plug under the oil filter housing and another on the side that leaked. An 1/8" plug that didn't leak was a tapered pipe thread. The leaker was a straight thread. The only thing I can figure out is that one is a pipe plug and the other is a set screw. Both use an allen wrench and have the same tpi. The set screw never acted like it would tighten up and probably could have been screwed clear through. Went to an auto parts store to get the tapered ones. IH dealer only had the straight threads.

 

[Watthour]

A straight thread could be a BSPP pipe thread. be aware that a NPR pipe thread is 1/8-27 with a 60° thread profile, while a BSPP thread is 1/8-28 with a 55° thread profile. A BSPP can be forced into an NPT hole, but it might not be the correct fit and should present some resistance as an indication.

 

[DWF]

I looked in my Cat hardeware marketing book from 1998. All of their 1" fine thread bolts and nuts are 1" 14 thread.
I use quite a bit of Cat bolts as they are good quality and I can get just about any of them overnight.
DWF