Saddle tank Joan caught the eye at the 2019 London Model Engineering Exhibition at Alexandra Palace. It is to the Molly Ann design from Polly Engineering, based on parts from the successful 5” gauge Polly design.

The locomotive is designed to be built using a minimum of hand tools. There is no drilling or soldering required and once completed it will pull around eight people.

Pre-assembled horn-guides on laser cut frames ensure precise wheel alignment. Wheels and axles are precision machined and keyed to facilitate ease of assembly, precise quartering and to eliminate slipping. Similarly, all axles and shafts are dimpled to locate the eccentrics and other parts of the valve gear In their precise angular positions. Wheels and other components are simply fixed using Loctite, and the engine will work properly without any of the usual trial, error and adjustment.

The boiler is hydraulically tested to twice working pressure and is supplied with a test certificate in full compliance with current EU regulations, and has a fusible plug fitted to the crown of the firebox. It is constructed from 1/8" and 3/32" copper, silver soldered throughout. Working pressure is 90 P.S.I.

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Editor: David Carpenter