David O says:

I used Atlas Snap-Track and Atlas switch machines designed for under table mounting. Both worked well. My track was on cork roadbed on a 3/8″ plywood table top (‘was’ because I moved and am starting a new layout). Make the hole in the top and roadbed plenty big (1/2″ diameter, I think is what I used). The leg of the switch machine HAS to be free to move completely. Also, the bigger hole makes it easier to align the switch machine, which I found the most critical part of the whole excercise. Best if you can reach under and position the switch machine while watching the operation of the switch on the table top. Manually test it, test it, and test it again for smooth operation before wiring and walking away. Also, make sure to snip off the excess leg that sticks above the track AFTER you have secured the switch machine. The leg needs to be trimmed pretty close to the railroad tie so as not to interfere with cars going over it. The first snip was scary because I thought about how much the parts cost and how tedious it was to get the switch machine positioned just right. Installation requires patience, but once you do one, the rest are much easier.