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old question about hot wire cutting

I have forgotten what to ask for exactly thru google here, so I will try to do my best. I am building a model rocket with a very large nose cone (8" round x 2 feet length) and need to scratch build a cuttong system to make it go from a cylinder of foam to a more aerodynamic shape. I am also broke but have plenty of "stuff". I was wondering if i could conver an old PC power supply for a source voltage, some pvc for the bow, but I aint sure what i could use for wire. sorta on a schedule and need to save every penny so ordering parts and waiting weeks for delivery (no CC) is out.

stainless steel wire? guitar wire? magnet wire? 12volts too much? need series resistor to limit current?

Reply to
tater schuld
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Seems to me if you can turn it,like on a record turntable,you can cut it with almost anything. A dremel and sand paper would be a place to start for me. Wire cutters need special wire and regulated power afaik.

wws

Reply to
wws

To make a cheap hot wire.

Make your bow. Bow handle must be non-conductive or use insulators for attaching the wire, else the wire will not get hot.

String it with any cheap 22 guage wire. Picture hanging wire will work and only cost $1 for 50 feet. Use something with iron in it, don't use copper or aluminum wire.

Attach a standard 6 amp 12 volt car battery charge to the wire to heat it. If your charge has a 2 amp setting try that setting first.

If the bow wire is too short the wire will get too hot and melt/break.

Take a scrap piece of wire try a 12", 18", 24", 30", or 36" long piece and wrap it around a wooden dowel, to make a resistor. Do not allow the coil/wraps to touch each other. Place the resistor in-line between one end on the bow wire and one battery charger cable end. It the bow wire still gets too hot, use a longer length of scrap wire to make a higher resistance resistor.

On a long cut several minutes the resistor will catch fire. Extinguish and make another resistor.

I cut my first set of wing cores this way. It does NOT work very well. But it will work if you get the resistance correct. The total length of wire determines how hot the wire gets.

If you already have a battery charger, you're up and running for only the cost of a $1 roll of wire.

Reply to
emcook

If this is a one-off project why not make it less complicated. Just use a sanding block to shape the foam. Get a cardboard box and make a cross-section pattern and use it to check your progress. You can't get much cheaper than that.

JR

Reply to
JR
*IF* I had a lathe. right now i am trying to see what i can do with what i got. the one webste mentioned before used a batery charger, a pvc bow, and a quitar string. these items i have. others say that guitar string dont work.

I like the router idea that someone showed a link for, I might go with that. bit more complex than what i wanted, but it apears to work if the guitar string wont.

Reply to
tater schuld

.010 guitar string on something a bit less than 12V should work.

Reply to
The Natural Philosopher

A drillpress, or a drill clamped in a vise will do, too. Use a rasp type file for roughing the shape, then sandpaper to refine the shape. You can get a metal disc that has a shaft on it, to glue, or glue and screw the blank to, at a home improvement store. They are used to make a sander for your drill, and are pretty cheap.

This will be a much better way to go, than the hot wire. I have done both.

To finish it out, you can use a half and half mixture of wood glue and brown paper bag material, topped with a bit of spackling compound to smooth it out.

A piece of plywood on the bottom end, with dowel rods drilled and glued into the foam will serve as a good anchor for an eyescrew.

Reply to
Morgans

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