Cutting Foam Parts by Richard Kares

If you have ever wanted to try cutting your own foam parts and you have a battery charger you may be half way there! The system I use is simple and easy with no purchase of special wire or transformers.
I use a Sears 2-10-50 amp self regulating battery charger (without a battery) set to the 10 or the 50 amp setting with 55" of .032 stainless steel safety wire stretched out on my workbench. This seems to give around 5 and 7 amps through the wire for the two positions, which heats the wire just about right. I put a heavy spring on one end for tension. This means I move the part across the wire. The more traditional method is a "bow" using the wire as the string and leaving the part stationary as you pull the bow wire over the part.
You will have to play with your own charger to see if it will work. Another method is to use a 12-volt battery with or without the charger and/or putting a rheostat on it to regulate it. Make a pair of templates out of something that will not burn or melt easily. I use 1/8" ply door sheeting or aluminum sheet metal. The edges have to be smooth and free of nicks or the wire will jump when you go across them, which puts ridges in the part. Pin the templates to the ends with plenty of pins making sure to square the templates to each other. A complex wing can easily be made using two different patterns for templates or not squaring the templates to each other. Now clip the charger leads to the ends of the wire and plug it in. The wire gets hot almost immediately. On my first attempt with a different system the wire turned red hot and melted through, falling on the bench. Very exciting!
-BE CAREFULL- The wire can burn you and/or your house down!
Take some scrap foam and run it through the wire. It should hiss slightly as it cuts and leave "stringers" as the wire exits the foam. If the wire is not pulled evenly across the templates the part will be out of square. One method to correct this is to put station lines and numbers along the edge of the templates and have someone help, calling out the numbers as you get to them. Go slow! Let the foam cut at its own pace or the wire will arc and not make a square part. Sand the part, add spars or sheet it and you are set!


Foam sheets can be found at most large hardware stores. Home Depot carries 4'x8'X2" sheets of EPS or extruded polystyrene, which makes a very strong core. Different grades and types of foam are stronger and or heavier and some can give off poisonous gas when cut so do this in an open area to be sure.


Foam sheets can be found at most large hardware stores. Home Depot carries 4'x8'X2" sheets of EPS or extruded polystyrene, which makes a very strong core. Different grades and types of foam are stronger and or heavier and some can give off poisonous gas when cut so do this in an open area to be sure.


I think you will be amazed at how easy it really is! If you have any questions give me a buzz at 206-246-3655 or E-mail me at pugsNstuff@worldnet.att.net
Richard H. Kares