Special Die

[Russ Hanscom]

Has anyone run across a 19/64"-32 die? (aka .2969"-32) It is the external thread on a tire valve stem. The internal tap for the valve core is readily available but all I can find for the cap thread is the cheap 4 in 1 valve tool, which may be fine for rethreading a bad thread, but is not suitable for cutting a new thread. I need to do a number so single pointing is not desired. Plan A is to see if a 5/16-32 in a Geometric head will collapse enough. A regular round die would be great but none of the special die sources I have checked carry that size.

A not critical, but would be nice, type of project.

[warmstrong1955]

What you need is a .305-32 die, for a standard Schrader valve OD thread.
Last taps & dies I bought, were from fleaBay. Industrial type tire shops usually have them, but they charge an arm & a leg for 'em.
Amazon maybe?

FYI, the valve core thread, is .206-36. I have bought some taps that were labeled .209-36, and they worked fine.

[Russ Hanscom]

Thanks. You are correct. Don't know how I got confused (any more than normal!) I have seen the .305" in abundance.

[warmstrong1955]

You're welcome Russ!

And, another tidbit of trivia, should you ever run across it; On the large bore valves & stems, used on heavy equipment, the valve core is .305-32, and the OD threads are .485-26.

Schrader.....was on opium....how else could he come up with thread sizes like that??

[Russ Hanscom]

The Schrader valve is probably 100+ years old (since 1891 per Wikipedia). There were lots of "different" threads in use then. Once one has become established by common use, it has a life of its own. Consider the light bulb thread. I have an assortment of strange, by current standards, taps and dies from my grandfather's shop.

[warmstrong1955]

The Schrader valve is probably 100+ years old (since 1891 per Wikipedia). There were lots of "different" threads in use then. Once one has become established by common use, it has a life of its own. Consider the light bulb thread. I have an assortment of strange, by current standards, taps and dies from my grandfather's shop.

But.....opium sounds so much more plausible Russ!
Maybe that has something to do with the day & age we are in now too! Times change.

Like my old Craftsman combo wrench and socket sets I got when I was about 12. They had 17/32" and 19/32" in the sets. One of those fit the bolts in the rear spring shackles on my '55 Chevy.....I forget which size though. Past that.....almost never been used.

[Russ Hanscom]

Exactly, I too have a bunch of the 32nd increment sockets and a few open end and tappet wrenches in the same calibers.

[Patio]

Russ, here is an idea. Thread milling on a manual lathe. I just watched Stefan Gotteswinter, from YT, do it.
https://www.youtube.com/watch?v=6_1Nlf-X4bw
I don't know if this will help or not. If high precision is required, it may not work.

[Russ Hanscom]

Interesting; it would take a fine cutter as it is 36 threads per inch. The material is brass - might be worth a trial for grins. I already have a holder for the die grinder.

[SteveM]

I always wondered why lamp parts are 27tpi.

That comes from pipe threading and the pipes they used for gas lamps, and it carried over when they went to electricity because they just converted the gas lamps to electric lamps.

Now I just want to know why my microphone stand is 27tpi.

Had a friend over to buy some tools. Asked if he needed anything else. He said "you got a 1/4-24 tap?'. Looked in the box, sure enough I had three of them. They were used on old stanley planes.

Steve

[warmstrong1955]

I have a 1/4-32 tap. It's what a lot of oilers are.

Why they made grease zerks in 1/4-28, but oilers are 1/4-32....I have no clue.

To make me go 'huh?' I suppose.
And have one more tap in the drawer, I've only used a few times.
I still blame opium!

[SteveM]

I have a 1/4-32 tap. It's what a lot of oilers are.

Why they made grease zerks in 1/4-28, but oilers are 1/4-32....I have no clue.

So that nobody would mix them up.

Same reason different gasses have different threads, even left hand vs right.

Steve