Regarding the use of do-it-yourself two-part polyurethane. A few years ago a friend and I did some experiments with 90-duro hardness PU to cast experimental sections of Weasel track bands. Wanting to see how the embedded cable looked in the results, I omitted the black pigment. The casting went ok but it is very easy to get tiny bubbles. If you could arrange to build or borrow a vacuum chamber then these could be greatly reduced or eliminated. The PU is easy to work with but it does have a shortcoming alluded to above, that is, chunking. It also has a tendency for splits to run along the cracks.
However the most interesting effect was when I left a test piece outside and it got soaked in the rain. The PU which had hitherto been a clear honey colour turned an opaque pale milky shade, obviously it did seem to absorb moisture, but unknown as to how much. Later on after it dried out in the sun it returned to its original state, but that swayed me against using home-cast PU for Weasel bogies wheels or track bands. I suspect the factory-cast stuff is much more robust, such as a forklift wheel, and we have explored that avenue a tiny bit too.
As for Big Tyre, we visited them a few years back to discuss Weasel track bands in rubber with kevlar or cable and they were indeed very receptive - the CEO gave us a good deal of his valuable time. In the end the major problem was the sheer cost, well outside our expense limit so we didn't pursue it any further unfortunately. I did see the carrier wheel mould there at the time and a re-rubbered wheel made from it and it was truly excellent.
Steve.
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