In the past I’ve always used L girders and plaster but on the new layout I thought that I’d give styrofoam a try. i had about 25 linear feet of two foot wide styrofoam glued down when I noticed that it wasn’t actually flat. This is the 2 inch blue stuff from Lowe’s. It is partially pre-scored the long way and the thickness varies from sides to middle. The difference in thickness is nearly a quarter of an inch. I had planned to glue luan on top of the foam where the track would be and them put on a homasote subroadbed and finally cork roadbed. I don’t see how the luan could possibly lie flat on the foam without a lot of planing and I think that I’d be better off tearing up the foam entirely rather than face that mess. Has anyone else run into thickness variations with foam and how did you handle it? Thanks, Werner
Have never noticed such variations in thickness. How quickly do the changes occur? I would cut your pieces of luan roadbed and lay them in place, see how much variance there is under the pieces. If there is a really high spot, a sur-foam plane would lower it. When it is reasonably level, put a bead of latex caulk down, spread it as you normally would. When you put your luan down, do not press it. Anywhere it leaves a gap, fill with a little more caulk, after the first bead has dried to hold your roadbed in place.
I have used cork on 2" foam and had no trouble with thickness variations,
Good luck,
Seems like your really building a complicated but very interesting subroadbed /roadbed systems. Fret not continue with your plan but first go back to Lowes and get yourself a small sureform file seen below. at the point where you have the high spot lets call it where the two pieces of foam meet lay the luan where u want it to go and trace the side with a sharpie on the foam. Use your sureform toll to knock down the high spot of the foam until your piece of luan sits flush. You can also take the opposite approach and just shim the luan in that area to make up the difference.
When you think of it your doing nothing ore then excavating the terrain of your layout just as the real railroads had to do. The world is not a billiard table.
Another thing you can do is build the roadbed up the amount of the difference or even use woodland scenics 2 degree incline starters to gradually correct the roadbed. You just cut it down to the section where it matches. Looking at the product a quarter inch will correct in 1 foot. http://woodlandscenics.woodlandscenics.com/show/Item/ST1412/page/2
Werner, I just use a sanding block and 80 grit paper to sand it flat. When I added a new section of bench I found it was a 1/4 inch taller than the section I was adding it to. Using the sanding block I got the two section to line up perfectly.
I have no idea what luan is, I use cork road bed. After I have the cork down I sand it as well with the sanding block. Makes for a nice level track.
Cuda Ken
I leave it alone, unless it’s at a joint, in which case I sand it down to make a smooth transition. I don’t put any wood on top of the foam, just under it. I use cork roadbed, right on top of the foam. The minor variations are like natural undulation in the ground. I use caulk to attach the roadbed and track so that keepsit level side to side but the very slight up and down grades that result from some of the variation don’t bother me. It’s not even enough to cause the slack to run in on a ‘downhill’ spot.
–Randy
I went to Lowe’s yesterday and looked at the current stock of blue foam and it was flat. The sheets that I bought several months ago must have come from a batch that wasn’t quite up to par. Of course, that’s relative. It would have worked fine in its intended use. I never thought about checking it since I’d never heard of a problem of this sort. It’s something I’ll be more careful about in the future. I’ll admit that my roadbed “sandwich” is probably more complicated than it needs to be. I’m trying to avoid gluing the track down. I know that I’ll want to change things a bit over the course of time and spiked track seems better suited to my approach. Later today I’m going to cut the first of the luan pieces and should get a better idea of what it will take to level things. I’ve got the file to remove material and I’ll keep my shop vac handy to clean as I go. I also made a stop at Walmart yesterday and picked up half a dozen line levels for $1.47 each. They should help me keep everything level. I found the suggestions about going with the flow interesting and thought about it as I looked things over again. I’ve got to admit that at the moment I could do a pretty good model of Southern’s Murphy Branch. But then what would I do with all the Pennsy engines waiting for that 4 track mainline? Thanks for the help. It’s good to get suggestions and tips that give you another way to look at things. Werner