On couple of previous micro layouts, such as the Bush Terminals one, I’ve used paper-backed foam core board as a media for benchwork construction. I am still a major fan of that approach and would recommend it as something to try.
I’ve read several articles describing a modification of that approach but more along the lines of foam clad in light plywood. Gordon Gravett described it in a rather nice article in Model Railway Journal and Mike Cougill has tried it for a project he’s working on. Mike wrote a great blog post describing his approach and you should check it out on his blog: http://www.ostpubs.com/the-p48-experience-pt-4-construction/
I was curious and really wanted to try it out for myself but didn’t have a layout in mind and didn’t want to waste materials on something that was only a study in benchwork construction. Last weekend I was cleaning out the shed and managed to unearth some door skin plywood and a panel of 1-1/2″ thick white (“beadboard”) styrofoam. Realising this for the opportunity that it was, I dug out some contact cement and set to work.
Investing a few minutes each evening and using only old material from the shed’s collection of “someday I’m gonna use this” wood pile I’m done. I’m really pleased with how well it worked out. Sounding only a bit like I’m hosting an infomercial on late-night television: I’m sold. It’s super lightweight. It’s strong. It won’t twist. Given its laminated layers it should not warp. Did I mention it’s deceptively light for it’s size?
It has a heart of foam. Not the nice extruded stuff that is so fashionable for layout construction these days but a sheet of beadboard, 1-1/2″ thick. We normally shy away from this becuase it’s real mess to work with. Clad in a protective shell of plywood that problem goes away.
The strength from this method comes from the marriage of laminating foam to plywood. I reason that you could extend this logic to apply a thicker sheet to gain a longer span. I doubt that weight will increase at the same rate as it would were one to use more traditional framing methods for a portable layout as I expect it will using this method. Not only less weight but I expect the rigidity to stay constant and it will far out-perform the equivalent in almost any other traditional framing method.
I used 1/8″ thick three-ply plywood that I’ve always heard and called “door skin”. It’s the same thing an interior slab door in your house is clad in – at least if you grew up in 1970’s Canada in a house decorated as a shrine to clear-finished faux-wood panelling as I did.
When described in the various construction articles, each author has described cladding all six sides with plywood. I didn’t have enough so used some 1×2 strapping I had. No other reason than, as James Barber would say: “You use what you got.”
I used water-based contact cement to bond the foam to the plywood. The wood at the perimeter uses just plain-old white glue from the school supply section of the grocery store.
Look Ma, no drywall screws
I’ll admit it. I’ve used my fair share of drywall screws to fix benchwork lumber together. It’s the kind of guilt secret I’ve been hiding from the public for far too long. I know better. I’ll try to do better in the future.
In this style of construction I did use some temporary staples to tie things together while the glue set but have removed them now. They wouldn’t contribute anything to any sort of strength and just looked clumsy.
Clean joinery made simpler
I reasoned that during the assembly phase I would make sure that the bond between each piece was very tight and the glue well set. Once the glue was set I’d just square everything up with a few passes through my table saw. Those lovely sharp corners and clean sides are evidence to just how efficient this actually was.
I’ve been drawing a lot of layouts and Krista’s super engaged in getting one of these off the ground. I guess I’m on my way now.