OK, so if I want to make a gauge, where do I start? I would think the distance from the back of 1 wheel to the back of the other would be a constant, but knowing how all the manufacturers love to be different, is that distance really "standard"?
If not the back-to-back measurement, then what? There's a lot (width) of angled tread to deal with if I have to determine where the rail rides (is it the middle of the tread width?). I would think the back-to-back would be the common and let the contact between wheel and rail fall where it may.
Then there's wheels that aren't "fast-angle" wheels. I noticed most/all of my Weaver 3-rail passenger cars have basically flat treads (maybe a 4-sided gauge with different tread designs, one per side). Just how many different designs can I expect?
