As I am planning my foam top layout, I have been pondering how to avoid space conflicts between Tortoise switch machines and benchwork joists should my plan be imperfect and I lack flexibility in turnout positioning. Forum contributor, electrolove, did a nice job of raising this matter back in February. Within this posting, I have included his graphic.
I have come up with a few ways to avoid these conflicts, and I would appreciate your feedback on them:
Use a total base thickness of foam that is greater than 3.25 inches, the height of a Tortoise switch machine. I was planning on using three inches (2" + 1") anyway;
Avoid or hold off gluing the foam to most of the joists. This will permit the joists to be repositioned. To maximize this flexibility, I am considering using one of Lin Westcott’s designs to position the L-girders above rather than below the bracket arms of wall-mounted benchwork. This keeps the foam far away from the bracket arms which are not movable; and
Use Aspenmodel switch machines, a lower profile slow motion machine. Does anyone have foam experience with these that they could share? Do these machines offer contacts for routing power to the frog?
Should I stay away from any of the three approaches above? Which sounds best to you? [:)]
Well, given that I’m told I overbuild my benchwork…
I use 1x4’s for the crosspieces, and if there was a conflict (i.e. item B above) I would probably just notch out the 1x4 to make room for the machine.
This would admittedly weaken the 1x4 (how much depends on thickness of foam), but I generally don’t span enough distance for it to really matter. you could also brace the remaining portion of the 1x4 (i.e. glue/screw additional wood to the remaining section) to compensate.
I use foam as well. This is a version of point one. Under turnouts use gator board, a foam sandwich with hard phenol or other plastic impregnated paper on both sides. The gator board forms a hard and flat surface for the turnouts (vastly reducing later running problems). It also forms a thin (1/4 to 1/2 ) inch structural substrate to mount switch machines, switch stands, signals etc. You can also reinforce it further with styrene sheet or profile for screws and machine mounts. The greatest benefit is that the machine and switch can be mounted on it away from the layout and then glued in place. I give the gator board a one inch overlap with the thick faom around it and a clearance of two inches from anything on it. With your planned foam thickness, it should be easy to have the cutout provide all the clearance and access you will need.
Consider plan #2. I’m not sure if you even have to glue the foam down. Your diagram only shows crossmembers. It does not show what the crowwmembers are attached to, or how they are attached and what they are supported by.
If your crossmembers create clearance problems, you can cut the offending crossmember out of the way. Then brace the crossmember by either using short pieces to drop down on either side of the Tortoise and another piece to span between the drops or by boxing each end of the cut crossmember by installing a piece between the two crossmembers on either side of the one you cut.
Another simpler solution is to use 4" of foam as your base. No clearance problems there! You would still cut all the way through the 4" of foam, and if you’re on top of a crossmember, only the wires from the Tortoise need to get past the crossmember.
I guess I lucked out, non of my tortoises impacted a joist underthe foam. But I do have a few point to point orientations which required the tortoise to be mounted ‘backwards’ with the bulk of the machine under the turnout. No big deal, they work equally well either way.
These machines have a SPDT set of contacts. I expect to embed mine in the foam by cutting out a little ‘grave’ for the machine. My foam is two laminated 1.5 inch sheets so I just need to cut the hole in the top sheet.
