PreWar Workshop: How to fit a Conical Oil pressure gauge fitting

Thank you all for the effort in providing me with a solution. Certainly I was heading down the flared pipe / compression nut route until the always extremely helpful Sue from Flexolite here in the UK sent me an adapter which I think comes from the compressed air industry that takes me down to a 1/4bsp thread onto which I can then start using standard and widely available fittings. Thanks again to all.

"Pressure" lines require "compression fittings". The lines themselves need not be copper, as brake lines are plated (minimally) to deter rust.

If I were you, I would take your gauge to your FRIENDLY neighborhood auto parts store(now chains), the PRIVATELY owned ones usually had a LARGE, TALL drawer filled with every bronze fitting under the sun. You will find your place in the sun there.

http://royalbrassandhose.com
http://omrudrafittings.com/brass_tube_flare_fittings.html

british american or euopean?

work out the angle of the cone and type of thread if not already done, then go from there...

If you don't want to ruin the gauge you could make a short adapter pipe that will fit the tread of the gauge and seals with teflontape or loctite on the gauge. At the other end you can make the desired flange/connection

concerning the quenching of copper, I used to make headgaskets and after some folding/moulding i quenched them to be able to fold further. So this seems to work in my experience

You should make a nut on a small lathe that has an included angle of slightly larger than the included angle of the gauge fitting.
Then slide it over a piece of piping you want to use and make a cone on the end of a pipe that has an included angle slightly smaller than the fitting.

Then heat the pipe to red hot and water quench it (it's not a myth, it's science, it softens up the copper which work hardens again when it's hammered/tightened).

Then fit everything together tight (do not overtighten, it's just copper) so the pipe stretches a bit over the gauge fitting and the newly turned nut secures the pipe on the top of the part.
It then seats only on a small section of the top part of the cone.

I've drawn up a simple sketch:
http://i.imgur.com/toS48L7.png

undo the fitting , refit with a conventional piece.

That flared fitting is used for many of the pipes on Stanley steam cars, just needs the pipe to be flared and a female cone nut to keep the pipe in place. Tolerates 600psi easily on a steamer. By the way the quenching of red hot copper to anneal it is a bit of a myth - quenching does not change the metal but just means you can handle it more quickly after heating.
Mike

There are many sices od a cone in the 20th
on Instruments.
The best way, put the nut with flat inside at the pipe, make a steelring with the same cone put it on the pipe, than make a cone on the copper pipe and it will fit perfect.

I had the same problem during my ten years at sea. aka Make it work from a loose selection of none standard parts. The trick with the cone is that the male fitting should have a wider angle than the female one, a few degrees is usually enough, and that the point of contact with the securing nut shoulder should be approximately where the two "cones", male and female, will seat.

Bit difficult to put in to words really. The actual seal needs to be a thin line backed by the locating nut. A big sealing face will not seal properly so don't over tighten it. Also annealing the copper pipe by heating to red hot then quenching in water will soften it considerably and make it seat well. A brake flaring kit or Air Conditioning pipe flaring kit is usually good start. Securing nuts can be made on a small lathe easily enough.