Foam and L-girder construction

[MisterBeasley]

I've been going through the Linn Westcott book on Benchwork. For my needs, L-girder looks like the way to go. However, that book only makes passing reference to using foam board, and the basic technique for fastening the tabletop (either flat or open) to the joists is to use screws into plywood. Obviously, you can't do that with foam.

So what do people do? Is it enough to glue foam directly to the joists? Or do most people use 1/4-inch plywood as a base below the foam? I'd like to keep this as light as possible, and foam sounds like it has the strength and stiffness required, but then there's the problem with the joists. Thanks.

[rrinker]

Take al ook at my web site. Not an L-girder in sight (always seemed WAY too complicated and a waste of wood to me. I'm no professional, but I had NO problems making cuts to accurate lengths and building my framework using regular open-grid construction WITH HAND TOOLS). And no plywood, either. The 2" thick foam is MORE than strong enough to not sag across 16" centers. The foam is fastened to the wood with Elmer's Carpenter's Glue, the yellow stuff. I tried Liquid Nails previously and after a week it STILL did not set up a good bond - it was dry and hard, but I was able to easily pop the foam off the wood. With the yellow glue, I could probably get it apart but I would surely damage the foam in doing so. After the 4 sectins were assembed and levelled, I actually had to slide it back into the corner, about 2 feet one way and a foot the other. Two of use lifted up on the layout and slid it back - no foam broke, nothing popped loose, etc. (that was BEFORE any track was down). It's all quite lightweight and strudy, the only thing you can't do is lean hard on it, it will dent the foam. Probably a GOOD thing over grassy areas (or what will be grassy area, anyway), but dents where the track had to go are not good.

--Randy

[orsonroy]

Randy's right: building a layout out of fom requires a completely different approach to benchwork. In general, L girder, box frame, or any other sort of traditional benchwork construction is a complete waste of time, material and resources.

True, you CAN build traditional benchwork and roadbed support, and just use the foam as a substitute for the hardshell scenery, but unless you're running indoor live steam, there's no need. One layer of 2" foam, supported ONLY with 1x3's set every 16", is more than enough to support any scale from Z to O. Foam is surprisingly strong and dimensionally stable, so you only need enough support under it to keep it in place.

Mt 12x25 three level layout is almost all foam. Basic benchwork construction is 2" foam laminated to 1/4" Lauan plywood, and attached to the walls with 10x12 U channel shelf brackets. IIRC, it costs me about $1.29 a square foot to build benchwork, as opposed to $2+ to build the same layout out of wood. It's also blazingly fast to assemble. I had 100 brackets and all the plywood (two levels of my layout) up in an afternoon. My lowest level, being 2 feet wide, is built on a simple 2x2 box frame, which supports two storage shelves and the bulk of my wiring. The 2x2 box frame covered with 1/4" plywood and 2" foam is strong enough to easily support me crawling around on top of it (I'm 6'2" and weigh 220).


Eliminating as much traditional benchwork construction as possible, including things like plaster rock castings, brings the cost of foam-based layout construction down below

[Anonymous]

I used to have an around the walls layout, 32 by 11 feet, all with foam on simple wood rectangular boxes two feet wide and eight feet long. You may also cut your foam and use it only under the track and road/town areas, to save foam cost. That's what I did, and it worked great. Very easy to use risers (I think mine were about 18 inches apart), to build grades into it, too. It's also super easy to lay track on foam. When I tore it down, sadly, it was easy to take up with a plastic dry wall knife, without damaging foam. I had used wood glue to hold it down, and it was solid. Foam's light weight and track laying ease make it a super train surface.