Foam

[Anonymous]

I need some info on the insulating foam. I am trying to decide how to build a 4X8 table.

I have a couple of questions:
1) How do you shape the foam?
2) Is it easy to use?
3) If I use it do I need a roadbed (or can that be used as roadbed)?
4) If I would need a roadbed what should I use?

Thanks

[ndbprr]

Well I see your questions have dropped down the list with no answers. I haven't used foam but can tell you what I have read. You shape foam a couple of messy ways using a cerrated knife or a rasp which makes lots of little pellets that generaly stick to everything becasue of static electricity. The cleanest way is to use a hot wire cutter that melts its way through the foam. Just use adequate ventilation when doing it though. They are getting fairly cheap in cost but you can also do the same thing by using stranded wire in a soldering gun. Just trim all the wires but one in the area you want the shaper and leave all the strands where it firts in the hole for the soldering tip. Is it easy to use. Yes becasue it is light and no becasue it is much thicker than wood so you need to poke holes throughit with an ice pick to feed your wires to the track. You can use the standard roadbed materials but you have to be careful with glues because solvents attack the foam and melt it. The most commonly used glue is liquid nails hobby which is inert to foam.

[Anonymous]

I used foam to cover our 4'X8' layout. The foam makes including a river very easy. After we cut out our river we glued it to the plywood using liquid nails. We then painted the entire foam surface an earth tone brown. I was going to build mountains and contours with the foam, but it is quite messy- similar to packing peanuts, only much smaller! so our mountain is good old plaster of paris soaked strips of tee shirts using left over peices of foam for support.
Regards
Ed

[orsonroy]

Wedge,

I prefer using foam over any other layout construction technique, since it's faster and cheaper (when done "properly") than any other method. Use wood glue to bond everything, and you'll have a fantastically versatile scenery and roadbed base that is more dimensionally stable than the standbys of wood and homasote. It's also much lighter!

To answer your questions:

1) I shape foam using all hand tools. A boxcutter with a extendable blade will cut the foam smoothly, and you can carve with it. A hacksaw blade is good for general shaping and cutting too. Probably the best shaping tool is the Stanley Surefoam rasp, which is specifically designed to carve foam (be sure to get the small one). I also use an old roast carving knife with a serrated blade. Hot wire cutters are generally dubious toys, and are slower than hand tools. Hot knives are nice, but again, pricey and really not necessary. If you're REALLY brave, a wire brush chucked into a poser drill works wonders, but ONLY do this with a shop vac running, or even better, outdoors!

2) Foam is easier to use than wood, homasote, or plaster, three old standbuys in the hobby. For your 4x8 layout, I would suggest using 2" foam laminated to 1/4" plywood, resting on sawhorses. The 1/4" plywood is only really there to deaden noise, since unsupported foam acts like a drum, amplifying noise considerably (probably it's only negative aspect).

There are several adhesives out there that can be used with foam, but I prefer carpenter's glue, because it's inexpensive and can be bought in bulk. Any adhesive, save for contact cement (which is VERY expensive in bulk) will need to dry for about a week before it's completely dry, but virtually any can be worked after a day or so.

Foam is especially useful for portable or small layout because it's dimensionally stable (it won't warp) and because it's so light. Many people, including myself, are beginning to use it exclusively for large home layouts. Mine is a 12x25 three-level layout, and I've seen much bigger layouts that are almost all foam.

3 and 4) "roadbed", despite what anyone might try to tell you, is strictly a scenic feature for indoor layouts. Cork or foam roadbed is shaped like the drainage profile on prototype tracks, and neither rerally does anything else (some say cork roadbed helps cut down noise on foam layouts, but I've had building experience with over 10 foam layouts, and haven't been able to detect a difference). You CAN use any roadbed (stick with cork or Woodland Scenics foam), but you really don't NEED to. I've eliminated commercial roadbed by buying sheets of 1/2" foam insulation, cutting them into 3/4" wide strips, and laying it like cork. 150 linear feet of roadbed costs about $6 using this method! To create the drainage profile, I simply run a boxcutter along the sides at an angle.

Hope this has helped! If you have any other questions about using foam as a layout medium, don't hesitate to ask!

[Anonymous]

Hot wire foam cutters are not necessarily expensive. I made my own from existing materials laying around. Granted, it is not the safest in the world, but it does the job. I simply took some nichrome wire I had from and old toaster I got at the thrift storeand clipped it to be about 6" long. Then I took two aligator clips and attached them to two seperate insulated wires. I hooked these wires to the variable voltage screws on my power pack, clipped the nichrome wire between the two aligator clips and it was done. The power pack is quite powerful as i found out. The speed setting neds to be only around 20 or 25 for me. Around 30 or 40 the wire glows red. It heats up pretty fast. I do not plan to use this for long periods of time, only intermittantly.
Reed

[Anonymous]

I agree with Ray. Styrofoam is the way to go. Not the beaded stuff. The extruded stuff is readily available in Home Depot type places but the way I get it is even better. If you are really polite, go to construction sites where they are building houses using the stuff. You'll find a dump site or maybe a dumpster box full of cut-offs. If you ask nicely they'll usually give you lots just to get rid of it. You may have to pick it overto find the cleanest ones but you can pick your sizes which can save a lot if cutting later. I use an old kitchen knoife with a 9" blade for cutting. The blade is flexible which helps. I tried using a hot knife but the stuff sticks together again after the blade passes through. And it creates fumes. I use carpenter's glue. It takes a bit to set up so you can move things around a bit if you need to. I have a 9" x 13' HO layout built only on 2" styro glued to L-shaped wall brackets of 1"x3" spaced at 12". No need for further support or sound deadening. It's equally easy to stack it for mountains and you can excavate for ponds etc. Great stuff.

[pbjwilson]

I use extruded foam for moduler layouts. I don't have the space for a permanent layout. It's great, fast and cheap. I cut it with a hand saw for large straight cuts or a utility knife for curves and irregular cuts. Caulk is a great adhesive for glueing and stacking them together. Another type of "foam" I use is upholstry foam, the stuff in the cushions of chairs. Cut up and pulled apart this type of foam makes good looking rock outcroppings. I also use caulk to secure this to the extruded foam base. Any small gaps are filled with more caulk or scenic ground foam. The 2" extruded foam is very rigid and doesnt bend. Smaller dimensioned foam board bends if not supported. I've picked up scrap extruded foam at new home job sites. The contractors are usually more than happy to give it to me because it is bulky and takes up space in dumpsters.

[scotttmason]

MAKE SURE YOUR TOOLS ARE SHARP. When cutting, the dull points on blade will pick up material and bind as you cut creating tear outs. Adds a certain random quality but not the safest if you have the blade out 4" to cut several layers of foam. Once the main profiles are cut, go back and cut face of surface using alternate angled cuts. This will result in larger, less messy waste chunks.