I’m about ready to start laying track, and I thought I’d use pink rigid foamboard instead of plywood for my subroadbed - seemed easier when I was in the planning stages.
Now I’m realizing that I know very little about using it. I know how to do everything with plywood, but thinking aobut using foamboard in its place leaves me with lots of questions.
Main ones:
I have up to 2.5% grades over most of the layout, so I’m thinking cookie-cutter method for subroadbed. Is that the best approach for foam too? What are the alternatives?
Any tricks with risers and foam that is different than with plywood?
How do you splice two sections of rodbed together? Same as plywood - glue a splice plate under the ends?
How well does foam hold up when stressed over a long period of time? I know it will make natural vertical curves going into and out of grades, but will I walk into the train room at some point in the future and find it snapped at the bend (I’m not talking about sharp curves here, but they do induce some stress in the boards)?
What’s the best way to cut foam? Electric knife?
Anyone care to share their experiences with foamboard?
Anyone know of any helpful reference materials? A quick Google search didn’t turn up much.
Maybe I should just go back to plywood, which I know how to work with?
What thickness of foam are you thinking of using? The 2" is pretty rigid.
I used the Ken Patterson approach of gluing layers of foam together and then carving the grade.
It is messy, he uses an electric chain saw too.
It is hard to get a even grade
Glueing foamboard is tricky. Gorilla glue or Great Stuff spray foam insulation work the best. Expired caulk does not ever set up. Liquid nails can eat into the foam.
2" foam (and thinner) can be scored with a knife and snapped. That works well for straight cuts. I don’t know how that would work on modest curves. I am chicken and don’t know for sure that the depth of a box cutter blade would be deep enough. Don’t tell my wife but I use the french chef knife and cut about 2/3 deep.
If you don’t know, Gorilla glue, needs water to activate it. Patteson mists it like you would mist scenery with wet water.
My railroad is mostly mountains and consists of 3/8" plywood with 1/2" pink foam glued to that as a base working surface. This provides an extremely strong, flat, non-flexing surface to work from. From there I use the Woodland Scenics foam riser system due to the fact that:
It is extremely versitile and easily shaped to any curve I need.
It is extremely accurate for creating slopes, as you can get 2%, 3% or 4% slope riser systems that are very consistant.
It is no more costly than buying sheets of foam, cutting the foam to the correct curves, cutting the foam to create the required slopes, then throwing away most of it as the biggest portion is now scrap unless you can use it somewhere else as filler. After you do all this, you find you made a small error in either the shape of the curve or the slope (or both) and have to remove most of it to correct the problem and go buy another sheet of foam.
The foam risers are easliy glued together and to the 1/2" base foam with low temp glue guns.
They can be dissassembled with minimum loss if you need to.
They can be bought in bulk packages should you need to.
They can be easily modified to change the slope with a Woodland Scenics Hot Wire Cutter, Foam Factory Hot Wire Knife or any other melting tool.
Once I have the foam risers in place with pins (not glued), I can lay track on the foam with pins and test for all the curves and slopes. You can even power up the track if you want to verify your slopes are not too steep, curves are not too tight or tracks are not too close together.
After you are happy with the locations, shapes and slopes of the risers, mark where the are with a felt tip pen, remove the pins and glue them down. The low temp glue dries and is workable in about 5-10 seconds.
You can then go to any of the Dollar type stores and buy 18x24 or 24x36 1/8" thick foam boar
I’ve never heard of anybody using foam for a cookie-cutter type subroadbed. I doubt very much that it would work. Every layout I’ve seen built on foam, other than using the Woodland Scenics stuff is based on Flatland.
Box cutters are kind of unsafe to cut 2" foam - you have to stick the blade out far too much. What i did was take a cheap putty knife and sharpen the edge - I saw this somewhere in the bobby press. Worked quite well. Key is never try to cut allt he way through in one or two passes, make multiple shallow cuts, at some point you cna just snap it and get a clean break. Compared to any sort of toothed blade, be it a saw or a knife, there’s very little mess.
Best way to do foam is flat and do the grades with Woodland Senics inclines. Works great and all you do is caulk and pin till the caulk dries, then run your cork which is caulked and pinned also. Take note that at the apex you need to trim the WS stuff for a smooth transition and at the bottom use extra caulk and stretch it between the base and incline for a smooth transition (have used bits and peices of whatever so that there is no saging).
For doing the grades on my layout I used a level that gives grade in %, Used a Surform scraper to cut the grade to final slope. Did my longest grade, double track, in less than a half hour. Was a little messy but nothing like using a chain saw! “GOOD GRIEF Charlie Brown !!!” Shop vac had it cleaned up in minutes.
