I wanted a HOm tractor for Neuburg but the Bemo models of the Shoma Tm 2/2 are few and far between and pricey when they are available. Looking at the Brungger and Finkle DVD drawings and pictures, thought that it might make a workable 3D project so did some CAD and was quite pleased with the outcome.
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Found a supplier of a 12mm gauge tram chassis with 42mm wheelbase which was just 1mm short of the prototype so thought that would be quite acceptable. Got and modified that chassis for DCC by electrically seperating the motor and pick ups from the chassis and fitting a 6 pin socket. Also had to replace the whitemetal motor retaining strap with a brass strip to get a neat fit within the body.
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So - 3D print later and as I have found before, I simply cannot get a good enough finish to represent a metal surface without a lot of effort and loss of detail. I did however get a really good result with the chassis and handrails which I printed for ePLA - an engineering grade PLA that ends up closer in strength to ABS as you can anneal it in a domestic oven after printing to cure.
For the bodywork, I took a different approach and sliced the flat survaces into SVG files and used SWMBO Cricut Maker to cut these from styrene sheet and assemble like a plastic kit. Interesting bits with this - by using the cuts out for the windows as objects, was able to cut these as exact fit for the glazing in acetate sheet By using these as a template both adding and subtracting 0.5mm made window surrounds out of vinyl sheet, black front and rear, silver for the sides. Handrails are made from scrap bits of Sommerfeldt overhead wire - off cuts give up a useful amount of 0.4 and 0.5 mm wire! The front and rear handrails I snipped off the print and replaced with wire to get the rounded effect which had been lost in printing.
Managed to install SMD lights into the headlamps on the front and rear frames which are very effective. Installed a Micro speaker and am waiting for delivery of the Zimo sound chip with the correct project loaded from Germany.
Decals are not as good as I would like - but I know how to fix them! They are created from a mix of screen grabs of the actual loco and the nice set of original artwork files the kind people at RhB sent me with my license. Orange background on white decal paper - but the orange ended up very slightly off, I do now have the RGB match to the RAL code and a test re-print looks much better.
Its been a very interesting project combining materials and techniques. Learnt things and it could be improved. On another forum Paul S sparked an idea which I am going to try - might even make an infrastructure version if it works!
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