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Where to find the tap to accept schrader core?

Unread postPosted: Tue Feb 17, 2009 11:44 pm
Author: newcomer
The internal thread to accept a schrader is as follows:

Metric: 5.30 mm OD x 0.706 mm pitch
English: 0.209 in OD x 36 tpi

I've been looking for this tap everywhere but can't seem to find it, even in specialized stores. If anyone could tell me where I could order this tap online I would be grateful.


Unread postPosted: Wed Feb 18, 2009 12:04 am
Author: starman
Are you wanting to tap metal or PVC?

If PVC and you can drill the hole close, you may able to just use a sacrificial schrader itself to tap the hole. If metal, no way that will work.

Interesting problem though, although I'm sure it exists out there somewhere.

Unread postPosted: Wed Feb 18, 2009 12:43 am
Author: newcomer
Metal, mainly brass or steel.

Anyways it's either a UNS thread or a special class of thread (can't remember but it's called special valve thread or something).

Edit: Think I found it. It's Valve Screw Thread DIN 7756.

What I found on Schrader website:


Unread postPosted: Wed Feb 18, 2009 2:42 am
Author: Gippeto
I skipped the whole issue by soldering the schrader body (suitably modified with the lathe.) into an appropriately drilled hole.

No tap required, and I didn't have to form the seat for the valve either. :)

I was modifying an airsource/ASA adapter. It now has a sealing check valve, and functions as a normal paintball CO2 tank.

Just to see "If it would work." :)

Unread postPosted: Wed Feb 18, 2009 2:59 am
Author: newcomer
Thanks for the workaround tip, Gippeto. After reading abit on this forum I realized that spudders would rather fabricate a component as cheap and practical possible while maintaining functionality than taking the high cost techy route.

Still, it would be nice if I could tap my own seat.

Unread postPosted: Wed Feb 18, 2009 3:05 am
Author: Gippeto
If you're set up for it, you could always make the reamer required to cut the seat.

You'd still need to find the tap though.

Unread postPosted: Wed Feb 18, 2009 3:31 am
Author: john bunsenburner
I agree to gippeto, its best to solder ou sharder in, the only thing you have to rember is to take the core out before soldering, i pretty much fried my sharder because i brazed it, the rubber just evaporated into nothing...Pretty annyoing!

Unread postPosted: Wed Feb 18, 2009 7:46 am
Author: ralphd
If anybody ever finds one please notify me. I'm in the air conditioning business and I haven't found one in years. The only thing i found and use is a tool for bicycles that chases the threads and removes the core.

Unread postPosted: Wed Feb 18, 2009 8:02 am
Author: newcomer
Hi Ralph think I found it. USD38 for a tap!

Look under Vg 5, there're two actually. One of them is called spiral flute, have no idea what that means.