Time to burn down the house... or, my home made hot wire cutter

[peteski]

Soldering guns use very low voltage and very high current secondary winding of a power transformer to heat up the tip made usually from copper wire (it has relatively low resistance, allowing the high current at low voltage to flow.  You are using much longer "tip" made from steel. Steel has a higher resistance than copper, and the extra length also makes the overall resistance of the "tip" much higher than the original. This might lower the current to the point that your new contraption will not heat up enough to melt plastic. But it is worth a try.

The coating on the wire is not a problem. You can just sand it off on the ends which are attached to the soldering gun.  If it works, the rest of the coating will just burn off as you use it.

[Bob Bufkin]

For a minute I though you were trying to get rid of a spider.

[MichaelWinicki]

Gotta luv those "See what I can do" posts... 

[randgust]

I once made a homemade welder out of a screwdriver stuck into a 20-amp 220v thermostat circuit on a baseboard heater.   I'd recommend eye protection and a bike helmet, as mine turned into a shower of sparks, nothing left but the plastic handle of the screwdriver, and flipped me upside down across the room and dumped me in an empty bathtub.    My well-meaning father had mislabeled the circuit breaker panel switch....BANG!!!!

I actually think it will work, or come close to it, but I'd be prepared for the worst, and make sure it's on a circuit with a 15-amp breaker that will rapidly trip if it creates a dead short.

[mark.hinds]

Fumes.  You're going to want some ventilation . . . and a mask.

DFF

Even better, make the foam scenery sections removable, so you can take them outdoors and do most of the cutting there.  Then only minor adjustments would need to occur indoors.  MH

[Smike]

Bout time someone stepped up to the plate to create a new TRW banner....

Reminds me of the one about the redneck saying.. "Hold my beer, watch this..."

[mmagliaro]

At the risk of incurring the wrath of State Farm agents everywhere....

GO FOR IT.
People are over-worrying about this.
I've done this, with that same soldering gun.
It worked fine.  (Can't remember exactly how heavy the coat hanger wire was, however)

Windows open for ventilation
Make sure the two ends you stuffed into the gun are sanded clean (no coating) so they make good contact.
This is important.  Even a little bit of resistance on those wire ends will keep it from working.  In fact, if enough
liquid goo from the foam insulation runs down inside those screw holes where the wire ends go, it can build up
to where the wire loses contact with the terminals and it won't work until you clean it all out.
(That happened to me)

Go outside to test it!  Over ground that is NOT flammable.  (got a concrete patio or something?)

Plug it in, pull the trigger, and see if it gets hot.  If it does, it will burn off any coating that's on there.
Try it on a scrap of foam.  If it works, you've got it made.

The original tips are copper and as Peteski already indicated, that coat hanger will have a higher resistance than the original tip, not lower, so the worst thing that can happen is it won't conduct well enough to heat up.

What could go wrong?

1. Fumes - both from any wire coating and the insulation foam when you start cutting.  We already beat that one to death.  Lots of ventilation.  I'd heat it up for the first time out doors, just so if the wire coating lets off really noxious fumes, you are outside.

2 It's possible (but remote) that the coat hanger wire won't handle the current and it will just burn apart.
It will shut off the second that happens, but it's always possible that a floppy, melted piece of wire
will drop off the iron and start something on fire.  So again --- test it a few times outside.  Make sure the wire
holds up.
(I seriously doubt this will happen.  It would have to get hot enough to melt steel)

[Xmtrman]

Used this kind of soldering gun many times in my R/C aircraft days.

I used bare #12 copper stripped out of romex (house wiring).
Each piece of romex gives you three "tools".
Short lengths are available at the orange or blue big box stores.

Good ventilation is required!

[peteski]

I'll mention this again: the coat hanger's toral resistance will be most likely higher than the resistance of the original heating wire element, so if anything, it will not heat up as well as it should . It should not cause short or overload.

Even if someone created a dead short across the output rails of the soldering gun, I doubt that it would even trip the circuit breaker for that outlet. If the soldering gun has a breaker built-in (most don't), that breaker would trip.  But if left on for a while, the transformer in the soldering gun would eventually fry.

So yes, give your wire loop a try. No need to panic.

[peteski]

Used this kind of soldering gun many times in my R/C aircraft days.

I used bare #12 copper stripped out of romex (house wiring).
Each piece of romex gives you three "tools".
Short lengths are available at the orange or blue big box stores.

Good ventilation is required!

Yes, copper wire is a better choice than steel because copper has lower resistance than steel. The tip which comes with the gun is copper (possibly iron-clad for longevity).  But copper wire is not as stiff as steel wire, so that might not be optimal.

[jpwisc]

Why try to articulate my thoughts when a crazy actor has it covered already?

[OldEastRR]

If I remember correctly real foam cutters use nichrome wire which is very thin and thus floppy.  The wire is available from either stores or some hobby companies have replacement wires for their cutters. The thin wire takes longer to cut through foam but has finer control and less smoke and fumes.
From  the look of your wire, I assume you're not going to be scooping out rounded valleys or grading gentle complex slopes.

[Kisatchie]

I'd like to know what pink extruded foam looks like after the foam cutters do their work. Pictures, anyone?


Hmm... they're classified...

[peteski]

If I remember correctly real foam cutters use nichrome wire which is very thin and thus floppy.  The wire is available from either stores or some hobby companies have replacement wires for their cutters. The thin wire takes longer to cut through foam but has finer control and less smoke and fumes.
From  the look of your wire, I assume you're not going to be scooping out rounded valleys or grading gentle complex slopes.

But the voltage produced by the soldering gun is way to low to pass enough current and get that thin wire warm (remember Ohm's law?)    The hot-wire cutters use higher voltage (around 9-12V and much lower currents).

Kiz,  extruded pink foam cut with a hot-wire tool (the one which used thin Nichrome wire) looks like extruded pink foam which has been shaped or sculpted.    The cuts are very clean.

[Missaberoad]

I'd like to know what pink extruded foam looks like after the foam cutters do their work. Pictures, anyone?

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