Hot wire cutter

[Didier Beaudoin]

Hi,

I'm looking to build a hot wire cutter to cut foam for the bodywork mold. I've found some references on internet, but I'd like to know if you guys have any advice about this subject. I want the wire to be about 2 or 3 feet long.

[kozak]

you just need a battery and a very thin wire thats all they are because the wire is so thin the battery is trying to push so much current through the resistance causes the wire to heat up, you could probably make one for like $5.

[Jarrod]

we made one off a piece of MDF as a handle(big C shape), a thin guitar string or something along those lines, and an adjustable power supply.

[Big D]

you can also make it so that it just plugs into the wall, although if you do that straight up, it vaporizes the wire instantly.
SO, what you do is get one of those variable supply boxes used for experiments in electricity class, etc. and find a setting that will heat the wire appropriately.
Ours uses 3 pieces of hockey stick, (made into an H, with a turnbuckle or sorts at one end, and the hot wire at the other) and an old extension cord. you can find everything you need in the trash, likely.

[TA]

You'll be needing a roll of "nichrome" wire. A well stocked hobby shop will carry it for the model airplane guys who cut foam cores for wings. A big-ass rheostat (swipe it from one of the Physics guys -- they always have them kicking around -- the Chemistry guys also use them to power flask heaters) would come in handy too.

http://www.aeroconsystems.com/electronics/nichrome.htm

Found this place on Google -- Also, if your scavenging skills fail you on the rheostat, a heavy duty dimmer switch from Home Depot would probably suffice.

Cheers, Ted

[Homemade WRX]

Originally posted by Jarrod:
we made one off a piece of MDF as a handle(big C shape), a thin guitar string or something along those lines, and an adjustable power supply.
we have pretty much the same set up...but turnbuckles for tightening the wire and we use a battery charger for the power supply...

[rajpr]

Safety wire will also work instead of the nichromium wire

[Dan G]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5959129484

[drivetrainUW-Platt]

here's my $0.02,
not sure about the tensile strength of the wire, but I would think that if you ripped the right toaster apart, that would work for cutting foam.......

[TA]

Originally posted by drivetrainUW-Platt:
here's my $0.02,
not sure about the tensile strength of the wire, but I would think that if you ripped the right toaster apart, that would work for cutting foam.......

Yes, but your mom will be extremely miffed http://fsae.com/groupee_common/emoticons/icon_smile.gif

[gug]

i would advise against a turnbuckle, because the wire gets alot of slack in it as it heats up (which makes for ugly cuts). use springs to control the wire tension. of course, it might not matter with something only 2-3 feet long.

[El Kevino]

We use our welder to feed the hot wire. DC, about 3-5 amps max. It's neat because we have a variable current pedal - you stomp it to heat up fast, then back off to make the cut. And we use a piece of stainless steel filler rod for the wire. Total cost: $0

[Sarsippius]

From a safety point of view, i was told last year that hot wiring polystyriene foam gives off cynide gass, you might want to be careful cutting inside.

[gug]

ahhhh, thats why i always feel so sick after cutting...

can anyone confirm this cyanide gas? i do a lot of hot wire cutting, and thats kinda scary...

[Igor]

I've read that hotwire cutting certain types of polyurethane could create cyanide gas. Polystyrene won't, but as styrene is a benzene based hydrocarbon you can pretty much assume it's vapours to be carcinogenic.

Igor

[gug]

ah good, i only use polystyrene.

carcinogenic? blah, the burnt skin of a chicken is carcinogenic. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif