1/2 - 12 tap

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earlgo
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Re: 1/2 - 12 tap

Post by earlgo »

whateg0: If you ordered a 1/2-12 tap I will stop looking for the one I am 'sure' is in my inventory somewhere. I remember seeing it and wondering why. Apparently it is the old 1/2" coarse standard.
Good luck with your parts.
--earlgo
(You know I will not stop looking until I find it. :roll: )
Before you do anything, you must do something else first. - Washington's principle.
whateg0
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Re: 1/2 - 12 tap

Post by whateg0 »

earlgo wrote: Mon Jun 25, 2018 12:54 pm whateg0: If you ordered a 1/2-12 tap I will stop looking for the one I am 'sure' is in my inventory somewhere. I remember seeing it and wondering why. Apparently it is the old 1/2" coarse standard.
Good luck with your parts.
--earlgo
(You know I will not stop looking until I find it. :roll: )
I find that the best way to find something is to buy another. Then when i go to put the new one away, there's the old one! i appreciate the offer.

Funny enough, I might not need it anyway. I decided to try 3D printing one last night. I had to make a custom thread in Fusion 360, but it printed well enough. I think I'll increase the wall thickness, though, so I can hit it with a file and polish it up.

Dave
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Harold_V
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Re: 1/2 - 12 tap

Post by Harold_V »

whateg0 wrote: Mon Jun 25, 2018 11:34 am Maybe I'm just old.
Perhaps, but I choose to think you're simply a better person. If there's anything I detest, it's talking to an individual who is supposed to provide help, but won't. Seems that is becoming fashionable these days---folks working in a job about which they know nothing, and that's the way they like it. They're often in it for the check they receive, paying no attention to the fact that are receiving unearned money.

Brings to mind the experience Susan and I had when we owned the castle. The county had purchased a piece of our property when the new road went in, so taxes on that portion were abated. All we had to do was show the cashier the letter that was sent to us and it would be handled when we paid our taxes.

I presented the letter at the window, at which time we were told "we don't do that here, they do it over there". With that in mind, imagine how it went from there. "Over there" sent us to another "over there", and that "over there" sent us to the next floor. The next floor gave us one of those "over there" things, which promptly sent us to yet another floor. That floor sent us to their version of "over there", which sent us back to the first floor, where we began our quest to pay our taxes. The clerk told us that they didn't handle that here, that it was handled "over there", at which time I told her no, that wasn't going to happen again, as we'd already had our tour of the City-County Building. I demanded that she either handle the payment, or find someone who could. Within 30 seconds the payment was accepted, with taxes abated as they were supposed to have been. Clearly, none of these people were willing, or able, to deal with their jobs. Why were they there?

That said, rant mode off.

The above story about paying our taxes really happened. Talk about frustration with inept people.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Glenn Brooks
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Re: 1/2 - 12 tap

Post by Glenn Brooks »

Holly smokes. So being this is a very interesting thread - about tap sizes - I went looking and got lucky with Mr. Google.

1/2” x 12 is definitely an historical tap size, known as “Sharp V Thread” and used up until 1909, having a flank angle of 60 degrees.

Here is the web site I found this on.

https://www.gewinde-normen.de/en/sharp-v-thread.html

Which brings up the question, with all these other thread specifications, is there maybe a newer Unified thread spec that includes 1/2 x 12? There is a apparently a current UN fine 12 TPI thread specification, where EVERY thread size is 12 TPI, from 5/8” to 6”. Although the specificTion does not go down to 1/2”, it does reach 5/8”. So maybe some manufacturer extended the thread to small diameters??

See: https://www.gewinde-normen.de/en/12-un-thread.html


Fascinating!

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
whateg0
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Re: 1/2 - 12 tap

Post by whateg0 »

There's a section in the Machinery's Handbook 17th edition that lists all of the 12 TPI sizes, though it starts at 9/16". Also interesting is that the mill/drill that gets these knobs is a Grizzly, which certainly wasn't around before 1909! I didn't look closely to see if it was a 60 degree thread or a 55, which if I am not mistaken would make it a Whitworth thread.

Dave
whateg0
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Re: 1/2 - 12 tap

Post by whateg0 »

FWIW, I did email Greenfield, so I guess we'll see if they respond about the "1/32" marking.

Dave
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NP317
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Re: 1/2 - 12 tap

Post by NP317 »

I was able to locate "odd" threading taps and dies at:
https://www.midwayusa.com/taps-and-dies/br?cid=23814

While rebuilding a 1901 Locomobile steam motor, we require 1/4 - 24 taps and die.
This size turns out to be popular with vintage motorcycles, bicycles, and ... old steam engines.

A good business to bookmark for our sometimes unusual threading needs.
~RN
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liveaboard
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Re: 1/2 - 12 tap

Post by liveaboard »

Could the 1/32 be the Whitworth number?

Whitworth has weird inexplicable [to me] numbering, and this seems to be a size from that place and era.
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GlennW
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Re: 1/2 - 12 tap

Post by GlennW »

liveaboard wrote: Tue Jun 26, 2018 6:53 am Could the 1/32 be the Whitworth number?

Whitworth has weird inexplicable [to me] numbering, and this seems to be a size from that place and era.
The designation would be 1/2 BSW.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
whateg0
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Re: 1/2 - 12 tap

Post by whateg0 »

Well, I got a response.

"David, this is a 1/2-12 British Standard Whitworth.

I’m not sure what the 1/32 means.

We don’t mfg this style of tap.

I would make a call to North American Tool 800.875.8277
They have this style of tap as a catalog standard."


I guess maybe I'll give them a call when I get some free time and see what they say. I'm really curious what that means, even though it doesn't really matter anymore for what I'm doing.

Dave
SteveM
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Re: 1/2 - 12 tap

Post by SteveM »

I had a fellow over to buy my old arbor press when I got a new one.

I had a bunch of taps in a box on the bench and I asked him if he needed any taps.

He said, yes, but I wouldn't have the one he needed - a 1/4-24, not a 1/4-20, not a 1/4-28, a , 1/4-24. It was for an old Stanley plane.

Opened up the box, pulled three of them out and said "here, take one".

Steve
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GlennW
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Re: 1/2 - 12 tap

Post by GlennW »

whateg0 wrote: Tue Jun 26, 2018 2:54 pm"David, this is a 1/2-12 British Standard Whitworth.
I'm not buying it!
12 Pitch001.jpg
Which still doesn't explain the odd designation.

A 55° BSW thread angle is fairly obvious.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
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