Working with Julian Watson on his Victorian Railways modules (http://vrdays.blogspot.com) we came across the problem of how to represent VR switches. His branch had a delightful lack of tie plates, and so, the first problem was how to reduce the thickness of the ties to allow for the slide plates. The second was how to represent the peculiar VR rail braces.
The Proto:87 Stores (http:www.proto87.com) sells some very nice museum-quality rail braces and etched slide chairs, but the rail braces won’t match the VR, and we would still be left with the problem of accurately reducing the tie thickness.
I had been thinking for some time about 3D printing the ties for a switch complete with rail braces and slide plates. So we decided to give it a whirl on Julian’s layout. We started with official VR drawings, along with some good detailed black and white photographs, which Julian had. In an evening, with Julian and Andrew watching, I worked up a SketchUp drawing of the ties and rail braces.
We then uploaded the drawing to Shapeways and a couple of weeks later had the casting shown in the photo above made out of their White Strong Flexible sintered nylon material. Unfortunately, the WSF didn’t quite resolve the rail braces, and so, most of them have disappeared. Their White Detail material will probably give a better balance between detail and cost, and so, we will try that next time.
For the proof of concept shown above, we glued the rail in place with Pliobond. The switch rod is PC board, and the points were hand-filed on three planes to a rather dodgy, but workable profile (the pukka ones from Proto:87 Stores would be better).
Notice that the prototype’s diverging stock rail bends near the tie before the points. This is a critical detail, and provided it is replicated, the points sit tight enough to the stock rails to work nicely. Overall, we declared the experiment to be an interim success, and with a little further refinement of the model, we will go ahead and print all of them for Julian’s model.
I also worked up a standard gauge version based on a CPR drawing. This one has a printed switch rod, which is meant to slide beneath the head blocks. Unfortunately, the tolerances are too tight, and so, it doesn’t really slide. It also incorporates a detente to hold the points over firmly, but I made the switch rod too well, and that doesn’t work either. It shows promise, though, and is pictured below.