I decided to go the plywood (3/8") and rigid foamboard (1/2") route for my tabletop. My question is; since I will have a two level design (elevated so the main passes over itself in a 'J' shape figure eight pattern), should I adhere the foamboard to the plywood first, then cut for the elevated portion, or cut one or the other first, then cut the other before gluing? My concern is; if together, the mess of sawing through both the foamboard & the plywood then supporting with the levels afterwards from the grid work underneath. I'm using the Lynn Westcott method. The room/layout is 9'x19', the layout is N scale and it is a double track main with a hump yard. I hope all of that made sense.
I am assuming that you are planning on using what is called the "cookie cutter" method, cut through the surface, then block up for your grades.
First, I would recommend a thicker foam, even in N scale. It will allow you more leaway in below track scenic features. In N, 1" is just over 13'. If you use 2" foam, a layer of plywood underneath is not necessary, just a supporting frame and a trim to protect the edges.
I have not heard of anyone cookie cutting foam, but with the 1/2" it would probably work. I would think that since you are going trough less than 1" of material, you could cut both pieces, after they are bonded together. As long as you don't use too much latex caulk, it shouldn't gum up the blade too much. As for the "sawdust" from the foam, a fine (blywood) blade shouldn't make too much. Keep a shop vac handy, even if you are just cutting plywood, helps keep the mess under control. You might try spraying the area you are cutting with an anti-static spray to help control the foam. I have found it helps a lot when I am cutting foam.
As I have not done this, this is the way I would try it. Maybe someone has some experience and can give you some better advice.
Good luck,
Richard
I wasn't planing on any mountains nor valleys. The 1/2" foam was half price (2nd's). I figured I can also go up. A good portion of the layout will be a yard. I'm in WNY.
Ok, related question; the small portion that will be elevated, do I really have to use foam? How about just plywood? How much of a audio difference on this portion would there be?