Foam Plastic

Discussion in 'HO Scale Model Trains' started by Old_Bob, Feb 2, 2007.

  1. Old_Bob

    Old_Bob Member

    Have been absent some; we are in the process of moving to Eagle CO and the process is overwhelming!

    My layout is still in my head, but I do have tacit approval from my wife; major achievement!

    Question is I read here about various types of sheet foam for carving landscape; pink, blue, white. Aside from the patriotic colors, what is the difference between them? I saw on one thread chunks of foam that didn't seem to carve very well; it crumbled. What are the materials?

    While I'm at it, what kind of knife seems to work best? Bread knife, serrated blade, or?

    I'm thinking in terms of at least 2" of foam under the trackbed and I figured I would lay that and carve it later to form hollows or small streams and the like. So I would want a knife that would cut cleanly.
  2. Jim Krause

    Jim Krause Active Member

    My heart goes out to you on your move. Been there, done that too many times.
    The foam that you want is extruded insulation foam sold at building supply stores (except in California so a whole lot of folks here have said) As far as model railroad use is concerned, color doesn't seem to matter. I have a mix of blue and pink. I shopped around and bought broken sheets at various lumber yards for quite a bit less than retail. I even picked some chunks up along the highway one day. Some people use a white foam with plastic vapor barrier over it but they remove the plastic. Don't use the packaging styrofoam as it tends to crumble. As for cutting, I have used hacksaw blades, knives, keyhole saws. You can buy some neat hot wire cutters with various shapes of wire.
  3. Doc Holliday

    Doc Holliday Member

    You can also make your own hot wire cutter with a soldering gun and a piece of stiff wire. I used No. 14 copper) Replace the soldering filament tip with the wire, making sure the wire doesn't touch itself. You can bend the wire into various shapes as long as it doesn't touch itself.
  4. Santa Fe Jack

    Santa Fe Jack Member

    "tacit approval" -- Sometimes, that 's all we can hope for! :)

    I've seen the extruded insulation foam boards in pink and blue, but never in white. The white is probably that cellular styrofoam stuff, which you don't want. That's the stuff that crumbles when you try to shape it. No difference between pink and blue other than the manufacturer.

    I've been experienting a lot with the shaping of foam lately, and here are my lessons learned:

    - The electric hot foam cutting knife is not only fairly expensive (though I'll give you one cheap if you want to try it) it is smelly nasty. The fumes from the melting foam are undoubtedly toxic. Yuck.

    - A simple pocketknife (nice and sharp) works wonders.

    - A one-ended hacksaw blade holder and coarse-toothed blade also works well.

    - My favorite shaping tool so far, though, is the lowly shaper, a woodworker's tool for roughing out shapes. It has a handle and a small (maybe 1.5" x 2") curved plate with many little blades on it, like a kitchen grater. It makes foam dust, but that is easily vacuumed up. This simple tool has done most of my shaping. I need to get some pics of that up on the site... (link in the sig)

    Also - one more consideration is that of layering the foam boards. I used three 1" layers laminated together. Serendipitously, I have discovered that having the topmost layer be 1" thick is perfect for mounting the Tortoise switch machines. I also need to add some pics of this nifty mounting technique, but if you simply cut a keyhole in the foam from underneath up to but not into the top 1" of foam, you get a nice snug fit with the perfect 1" of depth for the machine.
  5. pgandw

    pgandw Active Member

    The white foam is made differently - it is compressed beads, not extruded. It is nowhere near as strong, and much messier to cut. The "bead board" is almost impossible to directly finish to a plausible scenery surface or cut accurately (except with a hot knife).

    I recommend sticking to the extruded stuff - comes in pink and blue, sometimes green or yellow. I have also seen the bead board with a blue surface applied to it at Home Depot here in Northern California. But underneath the cover, it's still the same nasty white bead board.

    my thoughts, your choices
  6. yellowlynn

    yellowlynn Member

    The tool SantaFeJack is talking about is a wood rasp. Works realg good for final shaping. They also come in different sizes and shapes.

  7. Santa Fe Jack

    Santa Fe Jack Member

    Yes, yes -- that's the word I was looking for: RASP. Thanks.
    Need ... more ... coffee ...
  8. Old_Bob

    Old_Bob Member

    Hey, thanks for the inputs, guys! I understand now about the differences between the foams. I'll be doing this in CO so lack of supply in CA is not a concern.

    I have a couple odd knives in my tool box somewhere. One I recall has a long blade with a serrated edge; probably a "borrowed" bread knife. I'll try that one first.
  9. 60103

    60103 Pooh Bah

    The pink and blue are competing manufacturers.
    I think there is some white foam that is usable, but most isn't. You can tell the unsuitable because it looks made from balls of plastic (which it is) and the join between the balls is not good.
    Cutting with toothed tools will give you all sorts of nasty foam bits that seem to be attracted back to the foam and to anything else in the room.
  10. racer25j

    racer25j Member

    I'm in SoCal and I found some at Home Depot. It was the white foam but it's not the same as described earlier. It was about $19.00 dollars each for a 4X8 sheet, 2 inches thick. That's what I used for the subterrain. I was planning on picking up a few more sheets later on for the mountains. $19.00 beats digging small pieces out of the trash at furniture stores. One furniture store had a ton of it buut I turned it down. The owner gave me the impression that I take it all on don't take any. I envisioned the look on my wifes face when I brought a matress bag full of foam home and said thanks but no.
  11. Old_Bob

    Old_Bob Member

    I guess the desirable foam is the extruded type. Using a toothed blade WILL generate a lot of foam dust; good point! Best I aim for a sharp blade instead. Wonder if it works to cut the foam and mist it to reduce the static charge.
  12. Old_Bob

    Old_Bob Member

    I have been absent some, moving to CO; note new location. Had a terrible time getting DSL service here, until they finally sent a tech to my home. He knew exactly what to do, and it was simple. Don't even need a modem!

    Will spend more time here as I have free time; we are still in a mode of finding stuff in boxes. Good to get back to the important things of life, like HO model trains!
  13. Floyd

    Floyd Member

    Contractor Styrofoam

    I went to a lumber yard that is going out of business and they did not have any blue foam but what they did have was some pieces of 2" Thick x 40" Long x 18" Wide styrofoam looking block sheets which he told me was used by contractors as a system of holding concrete when pouring low walls. The material has square finger like projections which make it possible to interlock the individual sheets to fill the space needed. The price was $5.00 for the lot 16 pieces they had left. I was wondering if it could be used to cover the table top of the layout. Anyone have knowledge of this material? It seems sturdy enough but I was wondering if it would be easy to form, unlike the packing styrofoam that I have seen on the thread. Any info would be helpful.
  14. Gary S.

    Gary S. Senior Member

    For 5 bucks, buy it, and then experiment with it. Take a piece, cut it and shape it as if it was your layout. Paint it. See how it peforms. Then decide whether to use it or not.
  15. 60103

    60103 Pooh Bah

    Floyd: one of my friends used to work designing the applications for that stuff. It looks like a reasonable type of plastic, although a bit thick and expensive, but at $5 ...
    Just check that it isn't all beads; I don't think it is.
  16. A great tool to use for shaping foam is a curry comb. These are used for grooming horses, and can be found at tack stores. There are a few different kinds, the ones we want for model railroading use are metal, with serrated rings, like in the picture.
    Also, another excellant option for foam is medium density rigid polyurethane foam. This is more expensive than the styrene foams discussed above, but has a lot of advantages when it comes to carving and strength. A model railroad called the Tascosa & Calico was built with this material by John Olsen, and construction techniques covered in detail in the Oct., Nov., and Dec. 1993 issues of MR.

    Attached Files:

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