Blow Down Valve

[Alan Worland 1Participant @alanworland1]

I am having great trouble getting my brass tapered blow down valve on my water gauge leak free.

I have tried all sorts of grinding media from proper fine ginding paste through to a variety of paint cutting compounds and all seem to produce a nice even finish to the mating parts, but it always leaks! I assemble it (after a thorough clean) with a small amout of graphited grease for smooth operation.

Any ideas or guidance very welcome!

[Alan Worland 1Participant @alanworland1]

[TelstarParticipant @telstar]

Hi Alan. On larger water guage cocks we used “Brasso metal polish”, however make sure you have not managed to get a ‘step’ on your valve.  When lapping it is easy to leave a ridge at the end of valve, (at the thick end on the plug/core, or the thin end of the body) this stops the core fitting snug, and further lapping dosn;t always remove the step.

Hope this helps   Happy New Year Tom

[Alan Worland 1Participant @alanworland1]

Thanks Tom, you are right, I had made a real mess of the taper!

I ended up making a reamer to true up the bore of the valve then made a new plug as the original was now far too small  which I finally lapped in with toothpaste.

It was assembled with graphite and is now water/steam tight – thanks

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