3mm Society

From a London member

3mm London area group

Fourteen members gathered on Saturday 6 September for the third meeting of the ‘informal’ London Area Group at the Model Railway Club’s Keen House HQ. Wim Harthoorn was unable to join us this time, but Steve Driscoll was present, and introduced two informative and appreciated talks, by Andrew Shillito on locomotive chassis building and by Phil Smith on 3-D printing.

Andrew led us through the process considering both pre-formed frames and scratch-building, and gave a clear explanation of each stage, with useful tips that made it all sound very simple! Those of us who have yet to tackle a chassis will have the chance to find out for ourselves, as Andrew offered to host a ‘hands-on’ session at a future date. Whether or not to compensate the driving wheels was discussed, his view being that this – like several other issues, such as whether to use a flywheel – was largely a matter for personal choice. A rigid wheelbase, pivoting beams and sprung hornblocks can all give good results with care, while Andrew described his use of pivoting sub-frames holding the axles and set inside the main frames, in which slightly oversize holes allow the wheels the necessary freedom of movement. His practice of gluing a motor to the chassis, rather than bolting or screwing, appears to work well, using a five-minute epoxy.
Philip Smith reminded us that Wim Harthoorn has set up a Society working group to look at potential applications of 3-D printing, particularly its possible use in creating a ready-to-run chassis. While the process is already being rapidly developed for industrial uses, its application for railway modelling has some way to go before it becomes a proven technique. In particular, the ‘printing’ is actually achieved by depositing thin layers of material one above the other, and this can leave conspicuous striations at layer junctions. These can to some extent be smoothed away at extra cost, but complex shapes such as loco chimneys and domes are proving tricky to generate successfully – and describing the required shape to be formed, held as a ‘pattern’ in the computer for the printing process, is also laborious. Superglue appears able to bond printed parts together, and to other materials. As with etching, it is always worth talking to a company specialising in 3-D printing before going too far with a project. PD Models and Shapeways were noted as two helpful firms.
The next LAG meeting would be arranged for mid-February. Before then, we were encouraged to support the Model Railway Club’s Open Day on Sunday 16 November, in which the Society is taking part.

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