DUBS A
But I did want an NZR locomotive to complement my existing Model T and Fiat railcars.
A search of New Zealand Railway Steam Locomotive Classes soon revealed the 'A', 0-4-0T, at the head of the list.
Wanting a new G gauge project, live steam posed a suitable challenge.
The Australian Model Engineer’s Edwin project was a good place to start.
The provision of dimensioned elevation drawings by a fellow modeler was all I needed to make a start. Using the free drawing software, NanoCad, I traced over scanned images of the side and end elevations. This is a technique that I have used on my two previous models. Having scaled them to 1:24, I determined that the loco was only 228mm over the buffers!
Already having pieces of brass sheet, (ex scrap metal yards), I started by making the side frames and end beams. The four wheels were turned from bronze stock, coming from another modeler’s workshop. I was quite pleased when I managed to get the assembled coupling rods and wheels turning freely. And yes, there had to be some inbuilt slack.
The boiler, which is 120mm long x 40mm diameter, complete with safety valve
and Goodall filler valve, has been pressure tested. So too has the butane gas tank.
The butane gas tank with tapped hole
for the Ronson filler valve and the
poker burner without a gas jet.
The finished burner with Ronson
valve and jet assembly.
With the boiler and burner complete, I was able to raise steam, hopefully in sufficient quantity. Time will tell.
Another necessary part of construcion
was the displacement oiler,
with filler bung and water drain.
Cylinder and steam valve construction.
Originally I intended using a piston valve, since I thought this would be easier to make than a slide valve. The cylinder is made from a purchased ½ inch bore bronze bush. This was faced on one side and pinned together with two brass plates and the valve block. The whole assembly was soft soldered together.
Unfortunately I could not make the piston valve with sufficient accuracy.
I removed most of the valve block, back to the white line, and proceeded to make a slide valve assembly. The two contact surfaces were faced using cutting paste on a
piece of glass.
Slide valve and ports.
And fully assembled.
The parts disassembled.
The bolts are all 10BA and made to suit. At this time there are no piston O rings.
I expect that performance would be improved with them.
I had decided to make the engine reversible, with radio control, so had to make expansion links, fiddly work, and radius arms.
Eccentrics and expansion links.
Construction well advanced. Radius arm lifting levers in place. These will be moved using a radio control servo located in the left side tank.
By this stage I had run the engine satisfacturally on compressed air, in reverse too.
Only time will tell whether this project ever gets off the ground, or is that onto the rails.
Latest comments
26.02 | 08:23
this is a beautiful model. I first saw a ststic DM model at Napiers Lillip...
29.04 | 04:09
Fantastic video Dean!
20.08 | 11:21
Thats great Dean love to see the video.