Foam Curve Cutting Sanding Fiberglass

I remember an article in one of the RC mags about building a hot wire "lathe" that cuts foam into cylindrical and conical sections and anything in between. However, I don't recall ever seeing a hot wire cutter that can cut a curve. You might make a curved fuselage by cutting a number of truncated cones, glueing them together and then sanding them to the contour you're looking for. BTW, if you sand foam, try drywall sandpaper. It keeps the particles from gouging the foam. Of course, the hot wire cutter is THE way to cut foam wing cores. There are dozens of sources you can go to on that topic.

Morris

There is a lot of stuff online about cutting foam with hot wire. I've done some freehand stuff with a frame of wood, some cheap thin wire and a battery charger, and an extra length of wire for a rheostat. With a truckload of foam at your disposal you can afford to experiment and may get useable results by hand. More reliable methods take more work (like making templates and setting up weights or building a full fledged computerized setup. That stuff is too bulky for my workshop however. I have made formica airfoil templates and stuck them on the ends of a foam chunk for a guide. Takes practice.

I have not considered having a hot template though, the straight wire out in free space can cut a lot of different shapes. The thin wire would distort too easy when not pulled tight in the frame, you would probably have to find something thicker and/or flatter. Maybe some brass strips bent into the right shape with a hefty current. cutting it straight might be a bit of a challenge, but practice or suitable guides would help. Maybe I'll try it. I'll start with the trusty coat hanger.

Re resin, The polyester resins will melt the polystyrene foam beyond sanding but standard epoxy will not.

I just picked up some bigger stuff, didn't want to dig in the dumpster too much Fri. with construction workers around and have the Super rag at me. Hell, he has alot more space in the dumpster now !

The biggest is 3' X 7" X 8' and got a couple more of other shapes 8' long. Had the whole truck more than level with the bed , for free. My EE friend is going to love me , I better get on his project.

I was thinking of a rectangular blade like an over sized stainless windshield wiper blade backing and held tightly at both ends and kept just hot enough to cut but still stay the curve. Cutting straight lines 8 feet apart may bring up just as many concerns. Or is 8' wire ok??? If so I can work with that limitation , but for some reason I think the other way would be more useful.

Fiberglass bud kicking back on the beach (jerk) says latex paint first or what your talking about. Maybe surf board tech...

Saw my first micro plane today. Oooh that looks like fun !

Been scanning for the weed whackers next to the curb with no luck.

If you need to cut channels, tunnels, grooves, and wheel wells in foam you can use a soldering gun whith #12 wire replacing the tip and shaped to whatever you need. Mostly used to install stuff in wings like spars, servo wires and retracts. Phil AMA609

Found out that curves and long spans can be cut with hot wire. See Hot Wire Foam Factory