Styrofoam Cut – A Small Procedure, Big Impact

A while back, I built a Styrofoam cutting machine. That has now landed me a commission to cut Styrofoam cores for a Mirage: half-wingspan 40 cm, root profile length 86.3 cm, outer profile 11 cm. I had often heard about the difficulties of cutting such extreme shapes—that the burn-off on the outside was too severe.

Well, I figured I might as well give it a try. Sure enough, the result was unusable. The nose region was completely burned away on the outside, and irregular grooves ran from the outside toward the center. First, I tried blowing air into the cut with a fine nozzle; then I drilled holes about 15 cm from the outer profile (every 2 cm) to blow air into the cut from above—all with moderate success, but the result was still unusable. For the time being, I was at a loss, and I ended up with polystyrene waste. The solution would be a wire that gradually gets thinner. You can’t buy something like that. So I used sandpaper,

400-grit, sanded along the wire from roughly the center outward, with the sanding becoming more concentrated toward the outside. After about 5 minutes, the first attempt: The result was astonishing. While the wire struggled to make its way through the Styrofoam on the untreated side, it cut through the sanded side like butter. The wire got much hotter on that side. Now cutting was no longer a problem.

One more thing to note: At the start of the cut, the wire is embedded in the Styrofoam for a length of 40 cm; in the area of the nose strip, it’s over a meter. This means that the temperature difference between the coldest and hottest areas is greater here. The cutting speed and heating current setting should be closely monitored during the cut.

*Heinz
Wildi**Cartoonist,
Illustrator**Stoltenweg 3, CH-5703 Seon**+41
(0)62 775 26
46**www.heinzwildi.ch**
mail@heinzwildi.ch*