I've got an automatic chicken waterer (made by Little Giant) that uses what looks to be a truck valve stem and a common automotive Schrader valve. It froze again and broke a fitting and I have tried to find a tap and die in the past that matched up to these threads, but no luck. I tried Google and am probably using the wrong key words, but no luck there either. Does anyone know what sizes these would be? Thank you.
We went over this here a few years ago, so it should be archived on Google Groups. It's really odd and a couple of us did some digging to come up with it.
-- Ed Huntress
Reputedly:
Internal thread 0.209 inches (5.3mm) by 36 threads per inch (0.706mm pitch), External thread is 0.302 inches (7.7mm) by 32 threads per inch (0.794mm pitch).
I haven't confirmed these.
And I should add, that the reputed measurements aren't sufficient specifications for actually cutting these threads, if that's what you had in mind, although if you know thread-cutting, you can figure it out.
I went through that a while ago. The external threaded part of a Schrader valve is 7.7 mm (.302") x 32 T.P.I.
YOu think my memory is that good. I found it on the site below.
John
The following link it's
7.7 mm OD 32 tpi, or 0.794 mm pitch Minor diameter is 6.9mm Thread designation is .305-32 or 7.7-32
That internal thread sounds awful close to 12-36. I bet a 12-36 tap would do the job.
Most automotive stores sell a thread chaser for tire valves. It will fix the internal or external threads on a tire valve. I have several lying in my toolbox. Bugs
Even out here in the outback they are around, so you should be able to find one, check with your local tyre store!
Should cost less than a six-pack!
Hope this helps, Pete
First off, thank you for the information. I figured if I knew the size I could get the taps and dies, but they don't seem to exist. I've got the little 4 way tool with the thread chasers, but am really surprised that no one seems to make a tap and die set for these valves. McMaster-Carr doesn't have them and a google search doesn't pull up any, either.
I was able to make a replacement part from a piece of nylon and fudge the threads close enough that it seems to be working fine. But the lack of taps and dies is a surprise.
Any time I need these threads, I take a discarded valve stem from the tire shop garbage, cut the rubber off, wire brush it clean and silver solder it in place. I even have one of these complete with core and installation tool/valve cap in the glove box in case some a**hole pulls a core on my vehicle again. Gerry :-)} London, Canada
I've fought this several times while making custom accessories. I forget precisely what thread it is, but IIRC, it's a 5/16"-34... a REALLY bastard form.
I finally took one of the better quality chasers and hardened it to use as a tap (in brass, only).
I called Schraeder valve, and they DO make the tap -- about $140, custom-run only.
LLoyd
Don't have my books handy, but isn't it 1/16" straight pipe?
Dan
replying to Wally, shotgun wrote: A standard Shrader Valve male thread is .305 x 32 T.P.I. Taps are available but very expensive!
That's for the cap. It's .210-36 NS internal. I stopped working on air conditioners way back, mid '80s, but they also have Schraders and are differently sized. There are many standards now.
Here, maybe. $25.10 for a North American Tool tap.
But If you're just chasing threads, you can get a 4-way valve tool for $1.46 or four for $5.65 on Ebay. Tap, die, valve remover, and reamer.
What about "Judy Blow-up Dolls"?
None of my do...oops, nevermind.
Isn't 'Fast Eddie' the only expert on those?
What's that supposed to mean, asshole?
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