How do you Cut Styrofoam?

Question

there must be a special way to cut it. when i try to cut it, i end up with a rough cut and a mess of small styrofoam pelets that stick to everything.

i want to cut it smooth and flat like a factory does it.

Answer 1

Without knowing the thicknesses or the amount you wish to cut, I offer the same as others.

In Theater work and construction I use all the suggested methods, but in Theater for example I use a hacksaw blade also.

Also without knowing the type of foam you're speaking of, certainly the white large cell type is messier anyway.

I have two tools I use, neither is inexpensive however. One looks like a table top jig saw, but with a wire instead of a blade. The wire heats and I can run the foam throug it either in straight cuts or various shapes.

The other tool I have is basically a "Hot Knife" and has various "blades" that allow strich cuts as well as Molding cuts.

I think if the rough cut is a problem and you don't wish to spend large, then the utility knife is best. I especially like the one answer about the snap off blade type, but depending on the foam thickness I leave the blade extended as deep as the cut might have to be. Knife blades are inexpensive in any case. The usual utility knife blade fully extended cuts less than an inch of thickness, and it may be likely you'd have to make more than one swipe no matter.

Steven Wolf

Answer 2

I am in the construction business for 34 years now. When I have to use styrofoam insulation I cut it with a hot wire stretched on a curved pvc frame. I attach a battery charger to each end of the wire. It heats it up nicely in a short time. The wire will go through it smoothly making your cuts quick and easy.

Answer 3

you cut it like you would cut an angel food cake, with a long knife with a serated edge (and wipe the blade after every slice). Mark the styrofoam first with a pencil so you know where your cut will be and then use a "sawing" motion with the knife on the styrofoam.

Answer 4

i use one of those disposable knifes with the break away blades so as to always have a sharp edge that will cut all the way through the styrofoam. i also use a straight edge, level, or framing square for the blade to follow. we use styrofoam under siding as a flat backer board to level out the wall and add insulating value to the house, too. hope this helps, good luck.

Answer 5

Just one more thing. Cutting things such as model airplane wings requires a template, wing tip and wing root to form the desired airfoil. And the same is true if you are using the hotwire to form any shape desired.

If you are talking about foam sheeting, as for insulation, or siding, I use a very sharp 6" long steak knife. The key is not to use a sawing motion, but long drawn strokes

Answer 6

The hot wire tool can be made inexpensively. Call some hobby shops, and get some tungsten wire. Stretch it on a simple wooden frame. They will explain how to wire it at the hobby shop. It's easy, cheap, and gives professional results. You can then make jigs to cut different profiles.
My father in law makes some amazing model airplanes. He uses this method to cut the wings.

Answer 7

You can cut styrofoam with a hot metal wire. Depending on the size & shape you're trying to cut, this can be pretty easy. Try using a metal/wire coat hangar.

Answer 8

They sell a tool, often in craft stores, that will cut through it with a hot wire. It usually is a wire, held between two sticks, that you plug in. It basically melts through the Styrofoam.

Answer 9

hot wire, they make a tool specifically designed to cut styrofoam.

Answer 10

snap off blade knife, and not mentioned, cut at a sharp angle. Let the blade do the work, and replace often. For any foam, up to to 2 inches thick. Cheapest way I've found.