tyre valve thread size

[jim]

i was just looking around the shed for some taps/dies. found some nuts off tyre valves (i always save them, never seam to need them!).

just wondering what thread they were

found this http://www.gewinde-normen.de/en/valve-thread.html

its a .305" 32tpi / 7,747 x .794 pitch thread.

unless i'm missing something, how on earth did we end up with a thread that is neither metric or a fractional imp size

and whilst i'm on the subject, its bothered me for a long time that tyres are both imperial (dia in inches) and metric (the width)

i'm going to use the nuts on my poppin engine, just need to "pick up" the thread and open out a bit, it'll bother someone one day that i used M8 .8mm pitch threads

[Stilldrillin]

Jim,

There are some things in this life, it is better not to know..... 

I once thought about those sizes, when I was an apprentice learning to measure things. 

I never did find out....... That was 50 yrs ago! 

David D

[sbwhart]

Jim

Thats near as dam it 3/16 * 32 Model Engineering thread you can get taps and dies from a number of suppliers try Tracey Tools.

Hope this helps

Srew

[mklotz]

Thats near as dam it 3/16 * 32

Huh?  How's that?


3/16 = 0.1875 ~= 0.305  ?

Yep, true for small values of 0.3.


(or is this one of those weird British things like hundredweights that weigh 112 lbs?)

[tel]

In my experience the threads on Schraeder valves are always 5/16" x 40 tpi - don't ask me why.

[sbwhart]

 

Whoops I mean 5/16"

Some ones been swaping the little numbers around again.

Its been a long day

 


Stew

[Stilldrillin]

I`m still confused...... 

[Bluechip]

More confusion for you ... see 'Dunlop' threads ..

That German site has errors in it .. although not on tyre valve threads  it seems ..

http://www.watchman.dsl.pipex.com/thread.html

Dave BC