Your Projects

Some time ago, probably last year, at a club roadshow, we commented that there were no GWR live steam locos on the club layout. After some thought, I decided to try and convert an A3 into a Castle, based around an old Hornby Dublo cast body. I've finally made a bit of progress, so here are some photos etc.

I started the tender first, but the Hornby boiler is too tall/wide to fit into the Dublo casting. I bought some 25mm copper tube (Hornby boiler is 32mm) and added a set of live steam parts to convert it into a smaller/longer boiler that stood a chance of fitting inside the Dublo tender once I had machined it out as much as I dare.

I haven't bothered with a new frame to space the wheels correctly, but just cut down the Hornby plastic and threw away the trailing axle. It will do for now:

As for the loco, apart from being a lot shorter than an A3, the cylinders are much further back (relatively speaking). I started with moving the cylinders, by chopping out part of the front of the chassis and removing some of the flange that holds the rotary valve block onto the cylinder saddle. I removed the two rear screws and put new ones in from underneath, so it's all still held nice and tight. That allowed me to move the cylinders back by 8.5mm, almost the correct scale amount.

The cylinders are now screwed on to the chassis from above into two new tapped holes. Hopefully they won't keep undoing now as everything will have to come off to tighten them. As the cylinders move back, so does the rotary valve, block, oil chamber, superheater etc, which will all need managing.

I hadn't realised how tall the valve block + oil chamber are. The Dublo body rests on them, nearly 4mm too high to be screwed together properly. It all needed to be shrunk, so I machined 1.5mm out from the cast body, took 0.75mm off the top of the oil chamber and 1.5mm off the top of the rotary valve block, ensuring I kept the recess for the small O-ring. I also took 1mm off the mounting point for the lights board....hope that will be enough. It fits now, although there's no room for an oil screw/exhaust. I made a flush fitting oil screw and will need to make alternative steam exhaust arrangements. This photo is down the inside of the body, to show how much space is now available. It's not easy to see, but the yellow line is to emphasise the inside of the casting. There's less than 0.5mm clearance now.

From the outside it looks like this. You can just see where I have broken through the casting by over-machining the inside. That will need fixing in due course.

I also machined out quite a bit of width to take the live steam mechanism inside the body. The important parts fit, although I have yet to try the lights or the whistle.

The back of the superheater is now VERY close to the top of the gears, so I wonder how well the plastic ones will cope with the heat. I also shortened the timing shaft by 8.5mm to fit in the new space.

Next steps will be the shortening of the superheater-pressure relief valve pipe. I moved the valve forwards (it was sticking out the back of the cab), so overall I need to reduce the length by 12.5mm.

After that, it's the "cosmetic" stuff - double crosshead/slide bars & dummy valve mechanism in front of the cylinders. Oh and finding somewhere for the PCB & lights to go.

Another post will follow when I've done some more work on it.....but it won't be soon!

David