By Dave Watkins
Jack Wheldon’s writings in the Railway Modeller first aroused my interest in16mm scale live steam railways. His description of the Archangel “Brick” in 1977 made me long for the day when I might be able to afford such a live steamer (This article was reprinted in SMT 128, May 2009). Archangel models were way beyond my reach at the time. My first steam loco was the newly launched Mamod in 1980 which was much cruder and cheaper. I learnt a lot modifying and repairing the Mamod and after that I started building my own locos. The thought of one day owning a “Brick” never completely faded and after several years I started to think about building my own.
The prototype “Brick” was a very small locomotive built by W.G.Bagnall at the Castle Works in Stafford, just a few miles up the road from where I currently live. The local connection was another spur to building this model. It was works number 210 of 1879.
There appears to be only one known illustration of “Brick” which was published in the magazine “Engineering” in 1879.
“Brick” was built for Beckenham and Penge Brickworks. They are said to have had a tunnel just 5′ 1” high. The loco was built to fit, being just 4′ 10 ½” from rail to chimney top. This was the last of the very early Bagnall locomotives built with the cylinders between the frames at the firebox end driving the front axle. This accounts for the long wheelbase for such a small engine. The original locomotive was 1′ 8” gauge, wheels 1’ 3” diameter, wheelbase 4’ and cylinders 4” x 6”. Very little is known about the engine other than these basic dimensions.
A true 16mm scale model would really run on 27mm gauge track (26 2/3 mm if you really want to be precise). I decided to stick to 16mm scale to match the rest of my stock so set the wheels to 32mm gauge. An alternative approach to get the gauge correct would have been to work to 19.2mm to the foot.
In view of the lack of definite information this model is somewhat speculative. I had the height but could only estimate the overall length from the engraving above and then had to guess at the width.
Like the full size engine the model has cylinders at the firebox end driving onto a crank axle at the front. There the similarity ends as the model has twin oscillating cylinders of ¼” bore. I had spent some time with abortive attempts to use a single piston valve cylinder with slip eccentric and internal meths firing. This might just have worked if I had not completely failed to get the valve travel and port spacing to match each other. The best run with the piston valve cylinder was no more than a couple of yards before the works locked up solid. Piston valves with lap and lead do not like condensate, especially when the ports are not uncovered properly. Feeling disheartened I opted for a simpler approach. The oscillators have the added advantages of being self starting and are reversible from a lever in the cab to a rotary reversing valve. I drew heavily on the design of Tony Bird’s “Aderyn” steam motor.
The meths firing too was problematic. The tank seemed far too small for a decent run so I switched to a centre flue gas boiler. There was no more space for a gas tank than for a meths tank but you do seem to get more stored energy in the same volume. A cylindrical gas tank is located in the cab between the frames with the filler valve accessed through the rear buffer beam. I struggled with the gas burner design, eventually settling on a gas poker type which gives plenty of steam and is fairly quiet. The cab back, buffer beam, tank and burner form one assembly which can be removed by taking out two screws.
The cab roof is removable for easy access to the lubricator and it hinges to flip up to enable one to adjust the regulator when running. Water capacity is inevitably rather small. A Goodall type valve is used to top up and so a reasonable length of run can be achieved.
The wheel recesses, the frames and the coupling rods were cut on a CNC mill. The works plate was photo-etched from a master inkjet printer transparency. The only commercial items used, apart from bolts, nuts and rivets, are a gas jet from Chuffed To Bits, a gas filler valve from John Prescott Engineering and lettering from Fox Transfers.
I do find that the finishing stages of a model always take far longer than I anticipate. I had been thinking of leaving a plain finish but when I compared a photo of the painted model with the engraving above the lack of lining was obvious. “Brick” had been displayed on Bagnall’s stand at the Royal Agricultural Society show in 1879 and was dressed up with intricate lining. I used a bow pen for the lining on “Brick” but for future models I intend to try one of the specialist lining pens which have been described recently in SMT. The multi height buffer couplings and dummy brake blocks were added just days before the loco was entered in the 2010 National Show. There was no time to add sandboxes and piping; these are still missing.
It is a good thing that the judges don’t get to see competition entries in steam before making their judgement. My “Brick” runs smoothly but would not win any prizes for controllability. It can run slowly but that requires a delicate touch on the regulator and constant adjustment on a typical up and down garden line. There is nothing like a low powered live steam engine for finding out where the unintended gradients are on your railway. With the National Show approaching there was little time to make wagons for “Brick” to pull. I found the solution on eBay where Richard Stacey sells 1:19th scale bricks which are just right for 16mm scale wagon loads. The bricks are carried in a couple of Coopercraft NWNG open wagons.
When running on other people’s lines I hitch a brake wagon to the train. Eric Skinner gave me this wagon that he built round a flywheel drive toy car. It makes a great automatic brake by absorbing more energy as the loco tries to go faster.
There is a recent video clip of my “Brick” in action on YouTube:
Some working drawings of the model are being posted to the Yahoo “Steammodelloco16mm” group files. Several members of the 16mm Association, “Steammodelloco16mm” and the “16mmngm” e-mail groups were very helpful when I was designing and building “Brick”. Fellow members of Stafford & District Model Engineering Society also contributed, not least by tolerating early running sessions where “Brick” would either refuse to move at all or would take off like a rocket.
References:-
- Bagnalls of Stafford, A. C. Baker and T. D. A. Civil, Oakwood Press 1973.
- The First Hundred Bagnalls, Allan C.Baker, Industrial Railway Record 100, Industrial Railway Society, February 1985
- Bagnalls of Stafford, Allan C. Baker & T.D. Allen Civil, The Phyllis Rampton Narrow Gauge Railway Trust, 2008, ISBN 978-0-9544546-2-3
Dave Watkins
Postscript
Dave’s ‘Brick’ won the Allcomers’ Cup at our 2010 National Show. Dave has also made the drawings for ‘Brick’ available for download from the File Downloads area of the Association website.
