I’m about to start a new layout and need to cut a piece of 4x8 2-inch foam. I’ve never worked with this material before and wonder how I should go about making straight cuts.
Can I “score and snap” it like styrene? Or, do I need to cut it straight all the way through. In either case, what tools to you use to make these types of cuts? I think I’m going to be using a box cutter unless you have better suggestions.
Thanks in advance.
EdW
I use a Drywall saw. Has a rubber handle and is pretty easy to use. Beware the mess though!!
You can’t score and snap things that thick… You can use a jigsaw; I built most of my layout’s foam sub-roadbed using one. Jigsaws work great for foam.
The best thing to use is a steak knife, or other long-bladed, thin knife. Try to cut smoothly, with long strokes, rather than “sawing” with the knife. That way, you’ll get a better edge. You can score-and-snap, to some extent, but you’ve got to get at least halfway through the foam to have any chance at success when doing this, and even then, you may get a break where you don’t want one.
They make “hot knives” and “hot wire cutters” for foam. Both are relatively high-priced items. I’ve got one of the wire ones. It works fine, but I can only get 6-8 inches in from the edge of the foam, because of the design of the cutter. The foam also gives off evil gasses when you heat it with a hot knife or wire, so you want to do that in a well-ventilated place.
Hi Ed,
I’m currently building a layout and am using 2" blue foam.
It’s easy to cut. You can use a box cutter (extra work) or a long sharp knife (better). I found a very easy way. [;)] On each 8 foot long section, I drew my lines and then used my electric jigsaw with a fine cutting wood blade. It cut through the foam easily and quickly like butter without producing much dust. Once I finished, I gently pulled downward on the cut sections and “pop” they came off without a hitch. (the jigsaw blade cuts through about 1 1/2" inches, so the remaining 1/2" on the foam sections offered little resistance when I broke them off).
It depends on how smooth an edge you want. A serrated edge knife works better than a smooth edged one for me, the smooth edge knife is more likely to “rip” the foam. A circular saw works well, I haven’t used a jig saw but suspect I’d like the circular a little better as I’m more likely to get a straight line with it.
I find these works nicely for cutting 2" foam, I use a straight egde like a T-square to keep the edge straight.
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Most standard woodworking tools can be used to cut 2" (or other thickness) foam. it is more a matter of mess and cleanup afterwards.
For long, straight cuts use a table saw or circular saw. You’ll get a good, smooth, clean cut that is square. You can also use a router to cut out recesses in the foam. Sanding screen works well to smooth any rough edge and for finer adjustments.
I would think that a jigsaw would tend to leave a rough cut edge due to more tear out than cutting.
Sneak into the kitchen and grab a bread knife. They’re long and thin and glide through foam like butta and don’t leave a mess.
I cut my foam on my 10" radial arm saw. Leaves a beautiful smooth cut. Table saw or skillsaw ought to be just as effective. Bandsaw works too although the cut isn’t as smooth as the radial arm saw. Any kind of hand saw works too.
A serreated edge kitchen knife, or even a steak knife works well. Those electric carving knives also work well.
The box cutter knives work, but even with a sharp new blade, the foam tends to tear and leave a ragged edge.
I’ve been using this type of knife for 20 years and a filleting knife as my tools for cutting foam. Foam will dull any blade fairly quickly so keep a sharpening stone close by.
Re: Jigsaw.
Actually mye edges have been rather smooth, but as I pointed out I’ve been using a fine cut blade (small teeth, very close together).
EdW–
I assume you’re talking 2" extruded foam and not the ‘beaded’ type. If so, then a straightedge and any Olfa-type adjustable-blade knife will work just fine–you can usually pick them up at a hardware store for under $2–, w/o making a lot of mess. Just cut it straight through. As suggested, keep some spare blades or a whetstone handy, because foam REALLY dulls a blade after a bit. If you’re going to be carving foam into landforms, a knife will do the trick, but an even better suggestion is to get a ‘hot’ knife for forming. Wear a mask, though, the stuff gets smelly when heat is applied and it’s not very good for the lungs.
Tom [:D]
Ginsu kitchen knife - never needs sharpening! pefect for all sorts of stuff - I carve wood with it too. Hehe! 5 bucks for 3 knives at a discount store.
And you can cut a brick in half & then slice a tomato!![:-^]
Yep. You can do your work and then make sandwich at the same time. But that sandwich might taste funny. [:-^]
Irv
[#offtopic]The really amazing thing about the Ginsu company is how they can make stainless steel RUST
I used a straight-edge (yardstick) and magic marker to draw a line, then an electric carving knife to make the cut. Be sure to buy the wife a new one, though! [:-^]
You’ll find a box cutter blade is far too short for 2-inch foam. A long blade is needed to cut all the way though the foam. An old fishing fillet knife would work fairly well. You’ll need to “saw” with it to keep the slicing action going.
Cut 46+ sheets of two inch extruded foam with a box cutter and chalkline when insulating my crawlspace. Box cutter gets about 1/3 the thickness, do the other side, then snap it off.
Old handsaw will cut all the way thru, with quite a bit more work, and yields a better edge, except it sort of fuzzes up. Surform cleans it up if you need a “mirror polish”.
On the layout, steak knife for detail cuts, 12 inch sawzall blade with homemade wooden handle for rough cuts, and box cutter for sizing pieces before carving. Surform and wire bristle brush for smoothing and rounding. Handsaw for sizing the two foot by one foot by four foot floatation logs for the larger ridges.
Phase two terrain does away with two inch foam entirely. Been saving all packing styrofoam, in odd shaped blocks, often found in TV/stereo/speaker boxes, plus cameras, etc. Since we cover foam with a plaster cloth hardshell, no need to get fancy with the foam. Block out the terrain by trimming packing foam, drape plaster cloth from summit to layout base to fix in place and provide rough slopes, finish slopes with newspaper padding and duct tape, two layers of plastercloth for the finish terrain shell, time to paint and detail.
Best thing I have ever used is one of those serrated edged bread knives. I hope that helps. 