Cylinder drain cocks

[John RutzenParticipant @johnrutzen76569]

Well here's a problem. I thought I would make a batch of cylinder drain cocks, they are quite expensive to buy and I had all the materials to hand. There are drawings of them by LBSC, Martin Evans and Don Young and probably more. I have come unstuck though trying to make the brass washers with 5/64 square holes in them. I made and ground a punch on my Quorn and tried to square up the holes in 10ba brass washers but the things just stretch and even split. So has anyone successfully made cylinder drain cocks?

Incidentally I notice that in most of these descriptive articles there's no end of descriptions about how to machine a wheel, an axle or simple things but they never seem to mention the tricky bits like these drain cocks or bending the curved flare on the top of a tender side.

[John RutzenParticipant @johnrutzen76569]

[roy entwistleParticipant @royentwistle24699]

Small square files for filing holes in watch hands can be obtained from the likes of Cousins or Walshes

They are certainly smaller than 5/64 and about 2 1/2 inches long

Roy

[Dave WoottonParticipant @davewootton]

Just an idea, and I must stress never tried it, but if the washers split could you use a short length of brass rod with an o/d larger than the finished washer drill and punch the square hole then turn down to the required o/d and part off as many washers as required. Sounds like the washers are too fragile for the biff required, might be better to make a simple broach, which could be filed by hand.

Just seen Roy's post above, didn't realise you could buy needle files that small, they would probably be the thing.

Edited By Dave Wootton on 15/06/2022 15:53:33

[John OlsenParticipant @johnolsen79199]

I was going to say that I would probably try to file them, but Roy has beaten me to it.

John

[LukerParticipant @luker]

Trick is to have a lead-in and the slightest of undercut behind the cutting edge (basically just to remove the cutter radius)…

[LukerParticipant @luker]

A different washer for stops…

[LukerParticipant @luker]

Posted by John Rutzen on 15/06/2022 15:23:39:

Incidentally I notice that in most of these descriptive articles there's no end of descriptions about how to machine a wheel, an axle or simple things but they never seem to mention the tricky bits like these drain cocks or bending the curved flare on the top of a tender side.

I think you'll enjoy my construction series(s)

[roy entwistleParticipant @royentwistle24699]

Just a further thought. If you consider how washers are made ie. by punching, they will work harden. try annealing

particularly in brass

Roy

[noel shelleyParticipant @noelshelley55608]

Spark erosion will do jobs like this with ease ! Noel

[Howard LewisParticipant @howardlewis46836]

The washers will stretch because they are nit restrained, The washer needs to be compressed, hard, between two surfaces before the punching operation.

Howard

[duncan webster 1Participant @duncanwebster1]

Or in a recess in a bit of bar? That would stop them expanding.

[Nick Clarke 3Participant @nickclarke3]

Alternately why not go automatic and do away with the need for washers and the (usually) difficult and easy to damage linkage to operate them?

[John RutzenParticipant @johnrutzen76569]

Thanks for the replies everyone, for some reason i didn't get notified. I've done them by turning them from 3/16 brass rod. This was strong enough to take the stress. It also meant I could make them about 1.2 mm thick. I have tried automatic ones but I like another lever to fiddle with! I'm making a Jeannie Deans compound so I will have plenty of levers. Thanks for the pictures Luker, I do like your articles having done some castings myself including iron wheel castings and I make my own boilers.

[John RutzenParticipant @johnrutzen76569]

By the way Luker, how do you cut your threads right up to the hex? That's another pet peeve of mine, drawings with threads right up to the hex and no mention of how to achieve it.

[julian atkinsParticipant @julianatkins58923]

I use 2 x 10BA nuts locked together.

Cheers,

Julian

[LukerParticipant @luker]

Posted by John Rutzen on 17/06/2022 09:28:26:

By the way Luker, how do you cut your threads right up to the hex? That's another pet peeve of mine, drawings with threads right up to the hex and no mention of how to achieve it.

Hi John, my home made dies have the lead-in on the one side only, then the other side cuts all the way to the head, but this is saved for only the end operation as it blunts quicker. My cheap dies have one side ground to the first full thread (carefully/slowly to avoid damaging the temper). My ME dies were a gift from an old friend so they aren't ground. When using those dies I use a tiny grooving tool (I made by soldering a piece of broken slitting disk to some MS) to cut a groove at the end of the thread. I plunge 90% of root depth and the tool thickness is roughly 1mm. When tightening, the female part completes the thread and seals nicely…

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