Adding the Drain Cocks

These are the tales of Bloggin’ the Blog…

One of the ommissions with the Stuart Victoria castings set,  is that the plan makes no reference to the installation of drain cocks.   The cocks can’t be fitted to the cylinder conventionally,  since the bottom of the cylinder is obscured by the mounting flanges and on the piston rod end,  access would be prevented because of the valve gear arrangement.

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As an example the in-board drain cock would be buried under all this mechanism!

So the answer is to make connections to the bottom of the cylinder,  then with a bit of plumbing,  bring the drain cocks out to the side of the sole plate,  well that’s how I did it.

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The Victoria cylinder is a shared casting with the Stuart Beam.  For the Beam engine,  the two lands in the casting are drilled and tapped to take the steam cocks directly.   This does’t work for the Victoria as the cocks would be inaccessible.  So I’m drilling and tapping them to take a couple of connectors to take a 5/32 copper pipe.  I would strongly recommend making this the next operation after facing the steam ports,  not the very last as I did.  A mistake at this point would cost a lot of re-work.

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The connector in the centre is a standard 1/4 * 40 tpi fitting.  I’ve converted two of these to the design left and right of centre.  One end I’ve simply shortened to 4.5mm.  The other end,  I’ve turned off the threads,  shortened to 4.5mm and drilled out to 5/32 and about 8mm deep so I can silver solder in the copper drain pipe.

Next,  it’s necessary to bring the pipe to a drain cock.   I decided to make a brass connector (between the cock and the union fitting in the picture) from 1/4 brass rod that will be a press fit through the sole plate.   The connector has to be made in a specific sequence and I also used a collet chuck to hold the workpiece.    Step 1.  is to face and thread the bar 1/4 * 40tpi.   Then I used a centre drill to create the taper socket for the cone nipple.  The part off the piece 16mm long and clamp the piece the otherway round in the collet chuck.    Now face off,  drill 3.4mm and tap 5/32 to take the drain cock.

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Next,  need to drill the sole plate to take the brass connectors:

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To get everything square,  I mounted the sole plate on an angle plate on the mill bed.

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Finally, all installed less the pipe work.

The the pipework.   Not particularly pleased with the finished pipes,  but they are functionally OK.   I made a mandrel for bending the pipe and kept the pipe annealed during the bending process,  but still couldn’t get a good finish.   One mistake was squeezing a flat on the pipe whilst soldering on a nipple.  Oops.