Hal, I haven't, but LEDs and light sensors offer a possibility. As explained in a threas a few years ago, I jave converted all my operating cars to use loght sensors ratherthan slide shoes. They only open when the car is properly positioned at the coal or log dock. I am confident that the tolerance could be tightened up,
I still can't figure out why the brass shaft of my Bowser would have gotten very tight in the steel bushing. I could understand the clamps swelling and reducing the ID of the shaft holes, since they seem to have been zinc, but the 5/16" brass shaft and matching steel bushing shouldn't change. Right now my plan is to make new shaft to table/disc clamps out of aluminum, drill through them and the new 5/16" shaft (aluminum preferred over steel for ease of drilling), and use roll pins.
