Schrader 8v1-32 question

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Corby Dawson
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Schrader 8v1-32 question

Post by Corby Dawson »

Hi, I have an 8V1-32 tap and I want to tap a hole to accept a Schrader valve for a Nitrogen purge/back fill port an a project. Only thing is that I cannot find what drill size to use to drill the hole prior to tapping it! My google-fu has not been up to the task. Any help appreciated.

Cheers Corby
ian_krase
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Re: Schrader 8v1-32 question

Post by ian_krase »

If it's any help to you, traditionally 1/2 to 3/4 of the "depth" of the threads depending on how hard the metal you are tapping is.
John Futter
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Re: Schrader 8v1-32 question

Post by John Futter »

Corby
Ian got it almost right
This also depends on the tap you have got as to what sort it is
roll tap number1, number two or number three.

I have never seen 0.5 thread depth as an option in the engineers bible.
You need to get one of these, all and more than you what to know is in there.
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Rich Feldman
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Re: Schrader 8v1-32 question

Post by Rich Feldman »

Cool. First time I heard the size given as 8v1-32. Is the 8v1 part of some systematic nomenclature that you know of?
The thread hasn't changed since August and George Schrader began production in 1893.
Today's Internet gives the basic major diameter usually as 0.305", sometimes 7.7mm, occasionally 0.307", and (perhaps a uniquely Wikipedia value) 5/16".

Sounds like your tapped hole is to receive a valve stem whose OD is threaded for its full length. Do you have a matching nut, or valve stem cap, on which you can measure the minor diameter of internal thread? You will need epoxy or solder to seal the joint, no matter how high the internal threads stand. Would h=0 work?
Schrader_valve_advert_in_Horseless_Age_v43_1918-02-15.png
All models are wrong; some models are useful. -- George Box
Corby Dawson
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Re: Schrader 8v1-32 question

Post by Corby Dawson »

Ended up drilling a 9/32" hole (in 3/16" thick aluminum) and running the tap through. Worked great! Cut out silicon gaskets for each side and will also apply sealant to the threads when I assemble.

Cheer,

Corby
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