Switch machine mounting with foam scenery

Model Railroader Layouts and layout building
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'm primarily using the old tried and true splined sub-roadbed method on my new layout along with red rosin paper for my scenery base, but I wanted to try other methods of scenery as well. one of which is the use of foam board.

I have “Zero” experience using the pink foam for scenery and track work. I’ve read and been told you can use carpenters yellow glue to mount track work and it’s very shape-able so to speak by using a wood rasp and other shaping tools but how does one mount a switch machine to the underside of the foam? Would it be wise to use a thin piece of plywood under the foam?

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I model in HO scale. I have a fairly large 2" thick blue(same stuff-different manufacturer) foam layout with many turnouts thrown by Tortise switch machines. I use Shinohara, Walthers and Atlas turnouts. I cut a block of 3/4" thick MDF (Medium Density Fiberboard I think) that is 4" square. (The MDF really 3 1/2" wide I think.) The MDF I got came from Home Depot. After the track layout is established I cut an equal size hole all the way through the foam and use Liquid Nails for Projects to secure the the piece of MDF flush with the top of the foam, and drill a 3/4" hole through that for the throw lever. I lay the Woodland Scenics foam roadbed after the MDF square is dry. Then a smaller hole is put through the roadbed for the throw lever. The reason for the larger hole in the MDF is to give me a bit of wiggle room for the final installation of the switch(turnout) and the Tortise switch machine throw lever. I have a couple of double crossovers, and the MDF blocks there are 3 1/2", but as wide as it needs to be to mount two Tortises at each end of the Walthers double crossovers.I have never had this method fail me, and after ballasting there is no difference in sound between the areas with the MDF squares and the foam. I also have Caboose ground throws in the yards and side tracks. I use the same method, I do drill the hole for a throw lever (but I don’t use it for now, and it is covered up by the roadbed anyways.who knows when I may power a turnout…)There is enough room to mount the Caboose groundthrow at the end of the headblocks using small brads. The switches thrown by the Tortises get a scale switch machine at the end of the headblocks. If you want photos E-mail me and I will send them to you.

My scenery is also assembled using the Liquid Nails for Projects or Liquid Nails for Foamboard. The Yellow and White Elmers takes a long time to dry, and the pieces are not as easily misalligned when it is used between two pieces of foam

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The tricky part of foam is it won’t take fasteners, nails, screws, nothing. Everything has to be attached with glue. For an under table switch machine, you attach the machine to a small piece of plywood and glue the plywood to the underside of the foam.

Glue. PLZ300 foamboard adhesive works well and so does latex caulk. Net rumor has it that solvent based adhesives, specifically Liquid Nails, will eat foam. Last time I was at the Hardware store they had Liquid Nails for tub and shower enclosures, Liquid Nails for this and that, but none of the dozen flavors of Liquid Nails actually said “safe for foamboard” on the package. So I bought the PLZ300 Foam Board adhesive 'cause the package clearly said “safe for foamboard”.

The clear latex caulk sticks to plastic ties on flex track much better than Elmers or the yellow carpenters glues. The caulk is tacky enough to hold track in place without clamping, although weighting down newly glued lengths of track is insurance against trouble.

Wood working tools cut foamboard nicely. A table saw leaves a beautiful smooth cut. Wood rasps, saw edged steak or bread knives, and those Surform tools are also good.

I put a solid layer of plywood under my foam board partly to stiffen the fascia, partly to give something solid for the wall brackets to support, and partly to give a wood surface to accept switch machines, wire guides and whatever else might need to be fastened uner the layout.

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My previous layout was all foam. If you poke around on my web site you can see how I mounted switch motors from the top, using an idea I found on the NorCal FREEMO group’s web site. I also later experimented with one and found that latex caulk did a very good job of holding a Tortoise right to the bototm of the foam. No extra wood square, nails, or screws. Based on how hard I had to pull it to finally get it off, there’s no way it would have failed during normal operation.

As for putting down the track, I would also suggest latex caulk rather than wood glue. The caulk is slightly cheaper, and a bit more tacky so it helps hold things in place faster, yet still allows you to slide things around and get it all lined up. The only place I used yellwo glue was to fasten the foam to my wood benchwork - that held even though more than once I banged my head against the bottom. You can use the caulk method on wood splines too. No need for fancy caulks with silicone, just get the cheapest latex kind you can find. For the roadbed it doesn’t matter as much, but for the track I used the type that dries clear. It comes out white so you can see to run the bead and spread it out, but then becomes clear when fully cured. And use it sparingly - a couple of exampels are, if you have draen pencil lines to place the track/roadbed - when you spread out caulk you should be able to read those lines. If it covers the lines completely - you used too much. And when laying track, if the caulk oozes up between the ties, you used way too much. I did an 8x12, double main, sidings, and yard with 1 tube. $1.19 of adhesive. Even if I had done this on plywood with cork roadbed I would have done the same thing, $1.19 would never have purchased enough track nails to do it the old-fashioned way and nail it all down.

&nbs

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I don’t mount my switch machines directly under the points unless I can lift (or drop) the entire yard throat out and take it to a workbench. I much prefer to keep them just inside the fascia, connected to the points with an Anderson link (1/8" or smaller tubing and a bent paper clip) and monofilament fishing line under tension.

Since the only thing supported by the foam is the 2.375" length of tubing (for 2" foam) there really isn’t any need for other fasteners. The points are held in normal position by a weight, hanging from a small screw eye (which could just as easily be a rounded-edge hole) in any convenient woodwork. The springiness of the bent paper clip can take up a lot of overthrow in the ‘points reversed’ position. Having the switch machine right next to the aisleway means that I can make electrical connections and adjustments while sitting in a chair. That’s much more comfortable than standing on my head under the benchwork.

Just my [2c]. Other methods may be better suited to your conditions.

Chuck (modeling Central Japan in September, 1964 - as easily as possible)

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2-6-6-2, all gave you great advise, mainly the latex chalk. Depending on what you want to carve foam the foam would determine what you would use to cut it. Right now I am doing rock faces, using a bread knife, hacksaw blade, sanding block and my finger nails. Main thing to keep in mind, it is easier than most of us make it in our mind. I put off cutting for 6 months because I was afraid I would mess it up.

In this picture you can see the lines between the foam I stacked to make the cliff.

I wanted to see the lines, if you don’t want to see the lines, use latex chalk with your finger to fill it in. It is that easy.

In this picture you can see a mound I added to the bench. I ruff cut the foam to sizes, used a sanding block with 36 grit paper to final shape, chalk it down, used chalk to hide the seam again.

You can all so just paint over the foam, I use craft paint from Wally World, then sickens to taste.

Two methods I use to glue the foam together is latex chalk and or hot glue gun. Hot glue sets up very quickly so if I am in a hurry I use it. On the mountain I use both, it can be lifted off the bench so I wanted to be safe.

Road bed, chalk again, use push pins to hold the bed down around turns. I leave pin down for about a hour. I just spiked down the track to the cork road bed, I add some extra holes around turns to be safe. New section has had one spike work out in 9 months of heavy running. When you ballast, the glue will hold down the track.

There is a down side, it makes a mess! Next cutting session I am going to try this. Take a plastic trash bucket, cut a hole&nbs