Author Topic: Making Cylinder Drain Cocks  (Read 14131 times)

Offline sbwhart

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Making Cylinder Drain Cocks
« on: July 30, 2012, 02:15:13 PM »
I asked a ? about cylinder drain Cocks and you guys came up trumps with the answer, that enabled me to draw up some simple automatic drain cocks for fitting to my loco. A drawing of the cocks is attached.

So now to make them first job the body this is simple enough to do machine a length of brass to the required OD enough to make all the cocks required and part off to all the same length.



Then chuck them up one at a time drill through No13 drill and tap each end 7/32"*40 ME

Set the mill up to drill a 3mm hole part way through to attache the T peice using the vice stops helps with this. and with a slot drill mill spot a small flat.



Thats that bit done.

Then turn up a length again to do all the T peices required and thread 1/4"*40 ME and part off to required length, put a small centre in each one and at the other end turn a small pip a tight fit in the 3mm hole in the body, press them into the body making shure they sit down square on the flat.



Then turn up the two end caps



sorry about the poor pic but used the wifes camera whilst mine charged up and didn't quite get to grips with it.

The parts



Silver solder the T peices to the body.

Drill through the T peice into the body this is easy to pick up on the centre drill hole particularly if you have left the mill set up


 
Set the ball onto its seating by giving it a sharp tap with a hammer throw the ball away and replace with a new one after this as you'll knock it out of shape.

And this is where they fit on the loco



I have a few unused bodies left if any one wants to try them just let me know what size you're cylinder is tapped and I'll finishe them of and post them.

I just have to keep my fingers crossed know that I've drawn it up correct and that they work.

Stew

A little bit of clearance never got in the way

Offline Dan Rowe

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Re: Making Cylinder Drain Cocks
« Reply #1 on: July 30, 2012, 02:25:02 PM »
Nice Stew those look good on that cylinder. Thanks for the photos.

Dan
ShaylocoDan

Offline Stuart

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Re: Making Cylinder Drain Cocks
« Reply #2 on: July 30, 2012, 03:36:33 PM »
Nice write up pics there Stew

now lets hope they work as planed note the may not perform as you would like on air but as you well know steam is a different animal


Stuart
My aim is for a accurate part with a good finish

Offline arnoldb

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Re: Making Cylinder Drain Cocks
« Reply #3 on: July 30, 2012, 07:34:54 PM »
Good going Stew  :)

I'm curious as to how well these work...  And how they scale; I'll have to try them on a small engine one day.

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline Dan Rowe

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Re: Making Cylinder Drain Cocks
« Reply #4 on: July 30, 2012, 08:12:28 PM »
Arnold,
They are available for G1 live steam engines so they work even in very small sizes. Just need smaller drills and a smaller ball.

Dan
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Offline tel

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Re: Making Cylinder Drain Cocks
« Reply #5 on: July 30, 2012, 11:05:01 PM »
Yo Stew, your drawing is coming through as a blank page here
« Last Edit: July 30, 2012, 11:08:24 PM by tel »
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Offline modeng2000

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Re: Making Cylinder Drain Cocks
« Reply #6 on: July 31, 2012, 07:20:42 AM »
OK with me Tel.
John

Offline sbwhart

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Re: Making Cylinder Drain Cocks
« Reply #7 on: July 31, 2012, 07:27:35 AM »
Yo Stew, your drawing is coming through as a blank page here

Hi Tel:- checked things out this end and all OK

Stew
A little bit of clearance never got in the way

Offline sbwhart

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Re: Making Cylinder Drain Cocks
« Reply #8 on: July 31, 2012, 07:28:46 AM »
Good going Stew  :)

I'm curious as to how well these work...

Kind regards, Arnold

So am I  :ROFL:

Stew
A little bit of clearance never got in the way

Bogstandard

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Re: Making Cylinder Drain Cocks
« Reply #9 on: July 31, 2012, 07:30:22 AM »
OK with me as well.

For anyone else having trouble, I have converted it to a standard image below.

John

Offline b.lindsey

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Re: Making Cylinder Drain Cocks
« Reply #10 on: July 31, 2012, 02:15:01 PM »
Stew, I must be missing something here. What makes the ball go from the closed to the open position?

Bill

Offline sbwhart

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Re: Making Cylinder Drain Cocks
« Reply #11 on: July 31, 2012, 02:47:42 PM »
Thats something I also had problems getting my head round Bil  :thinking:l,

I think what happens is that when you get water condensing out into the cylinder it builds up a back pressure that lifts the slide valve off the ports causing a pressure drop that allows the ball to drop off the port and allow the water to be ejected, when the waters gone the slide valve seals, presurising the sytem and sealing the ball.

I've seen these type of Cocks work so I know they are effective, but I'll stand correcting on how.

Thanks for your interest

Stew
A little bit of clearance never got in the way

Offline Alan Haisley

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Re: Making Cylinder Drain Cocks
« Reply #12 on: July 31, 2012, 06:22:21 PM »
Without cylinder pressure, the ball will fall from the seat; even with the cock full of water. At that point, water in the cock and cylinder will drip out and most will be cleared. With steam into the cylinder, the ball will be "washed" toward the seal, eventually mating up and pressurizing the system.


Another design would have two balls with a seat at each end so that if the cylinder is on a grade rather than level, at least one of the balls will be depressurized and allow the water to exit. It's probably unlikely that a grade steep enough to block the single valve style would be found on a rail line though  :Lol:


Alan

Near Raleigh, NC, USA

Offline doubletop

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Re: Making Cylinder Drain Cocks
« Reply #13 on: August 19, 2012, 10:47:56 AM »
Ah! new thread I wondered why I'd not been pinged with these updates

PM sent Stew

Pete
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Offline robmort

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Re: Making Cylinder Drain Cocks
« Reply #14 on: November 01, 2012, 02:16:42 PM »
A simpler solution which is also better for scale models, especially small ones, is to install the ball valve in the bottom of the cylinder wall ends, then you don't have to make separate fiddly devices.

This method is shown here:
http://www.modeng.johnbaguley.info/locos/25inch/A1/A1-2.htm

- bottom of page.