Hi Bruce,
I've installed over 70 Totoise machines under my layout and the wobble you mention has never been a problem. Just do as others have suggested, use 2 screws in opposite corners and that's it.
By the way, when I first got my machines, I talked to the owner of Circuitron (the company that makes the Tortoise) and he suggested I drill a 1/2" hole under the turnout's throwbar to leave plenty of room for the wire and also allow for adjustment. When I say "adjustment" I mean that you may have to offset the wire from the middle of the hole to be sure that the throwbar of the turnout throws equally to each side.
Here's a trick I use. I apply power from a DC power source to both outer terminals on the bottom of the Tortoise, to get the wire positioned EXACTLY verticle. If the wire goes too far to one side, I simply reverse direction on the power pack and try again, till I get it vertical. Then, when I get under the layout to mount the Tortoise, I make sure that when the wire enters the hole in the throwbar, that it is not pushing to either side. Actually, before I get under the benchwork, I place a piece of masking tape over the throwbar to hold it in the middle of the throw. That way, if the hole I drilled is slightly off center, I can adjust the position of the Tortoise accordingly.
Using this approach, I've managed to get most of my Tortoises to throw with equal pressure to either side, which is what you're aiming for.
Hope this helps.
Mondo
They wobble because of the way you are mounting them. What i do is first mount them to a piece of scrap 1/4" plywood then mount the plywood to the layout...
chuck
I have only two Torti and they both have their casting halves off by a few thousanths. This results in a wobble when they are placed on the underside of the layout. It is hard enough to fasten them up with screws let alone screws and spacer washers.
Question, can I sand the mounting surface flat without messing it up?
73
Bruce in the Peg