Scale Jr.

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I am building a scratch built airplane with foam wings, however; i have no idea how to make a Hot Wire. I think you need to use some kind of wire called Nicrome wire or something. I think it transmits the electricity into heat better. How do i get electricity to the wire, or how do i get it hot? Thanks in advance...
Rusty

jeang

got to this web site http://webpages.charter.net/rcfu/ and look under construction u should find what your looking for.

jeang

Scale Jr.

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Thank you, that site is helpfull
Do you know where to get the Nichrome wire? Also, how do they make foam fuselages? do they make them in sections like the corsair wing?
Rusty

Rubbie

Try http://www.tekoa.com/ they have a whole bunch of wire available I use it all the time with both their power supply and a 12v car battery and 12v car battery charger. I know it's not Nicrome but some guys go to the fishing store and use wire that they by there. I don't know what the best wire to use is but the stuff that I got from tekoa works great.

Flypaper 2

Been using .020 piano for many years and many wings. Works great.

Scale Jr.

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Hi,
How do i transmit the electricity through the wire?

Jim_McIntyre

I use a used high e string from my guitar attached to a hockey stick, powered by a 12v car battery charger with a light dimmer wired in to set the temperature.

Hope this helps.

dr_wogz

My Feedback: (3)

Yeah, for power, mostr use a car battery charger. preferably one with a varioable charge rate (so youcan set a tempurature)

Others use a lab bench top power supply, variable voltage.

RCM Magazione has an anthology book on foam cores, and how to cut, and cover them. It's worth the <$10 cost!

Scale Jr.

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Thanks guys, keep em com'n!

RJCapt.

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I've heard an old model train transformer works great too...

pewter

Coincidentally, on this my first day on the site I've just spent the day making a hot wire rig. The wire was extracted from an old hair dryer. The element was fairly tightly coiled, so I unwound it by threading it on a kebab stick, clamped one end of the wire in a vice and pulled the wire off the stick, letting the stick rotate under friction in my hands. This straightened the wire sufficiently to avoid kinks. I ended up with 20 feet of wire.

A UK hairdryer element is about 2 ohms per foot resistance, so a 3 foot cutter at 6 ohms will take 2 amps from a 12 volt battery, and two amps gives just about the right temperature to cut foam. Ideally though the source needs to provide more than 2 amps to cope with long whole-wire cuts where the block of foam cools the element somewhat.

To mount the wire I've used two shelf brackets fixed to the ends of a 4 foot beam. The wire is tensioned at one end with a spring from an old garden chair. The wire heat is adjusted by sliding a crocodile clip along the wire at present just to prove the operation, but I'll probably use a transformer and dimmer switch to power the whole 4 feet. This will be used to cut wing sections.

A small cutter for detail work can be made by driving a wire loop from a trigger type soldering iron with its element removed and replaced by piano wire undercarriage legs with the cutting wire stretched between them, held by wheel collets. Some experimentation will be needed to avoid wrecking the soldering iron

Flypaper 2

12 gauge copper house wire works good in the soldering gun.

DougT

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To make a cheap, strong wot wire cutter bow, go to an electrical contractor shop. They always have lots of scrap electrical conduit laying around. If you talk to the owner/manager and tell them what you want it for, they many times will give it to you for free. Have them use their tubing bender and make 2 90degree bends on the ends. You can then rig up your wire supports/spring. For me 3/4" or 1" seems about right. Mine's 4' long.

skychief666

I made the nistake of buying an auto cut off (smart) 12 volt battery charger and when I hook the wire end post to it it thinks the battery is charged and shuts off...no all I can use it for is for the stupid reason of actually charging car batteries...what a dummy move that was.

crashed2

My Feedback: (4)

Try this for the power supply.

http://www.nsrca.org/technical/tip_t...wer_supply.htm

I built this very thing and it works wonderful! Got all the parts from my local Radio Shack. I think the total cost for parts was around the $40.00 range.

As far as NiChrome wire, I get mine from Tower Hobbies. Its the Woodland Scenics Foam Cutter Replacement wire. It comes in 4ft lengths.

Be sure to use a spring on one end of the wire, so the wire will keep its tension when it gets hot.

Also, make the bow from something that is nonconductive, otherwise you will just short out the power supply. I made mine with a piece of 1x4 and a couple of 1/2" wood dowels. I plan on trying carbon fiber.

I first tried the car battery charger method, it worked, but I had no heat adjustment. Not a very good way to cut foam.

Good Luck!

jeremygaughan

I got a stick about four feet long and put a 1.5 feet stick at each end. I put a hole through the middle of the sticks and screwed them to the big stick so that they could rotate if pushed hard. I put a guitar string across one side of the two sticks and wrapped a bunch of string around the other side. Then I put a small stick through the string and started winding. Once it was wound tight enough I let the stick stop against the main four foot center stick.[/img]

Johng

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Inconel will be the best thing to make hot-wire from - just because it has very little thermal expansion. For all I know though, that's the same thing as nichrome. Inconel is some sort of nickel alloy, it was used as the skin on the X-15, among others, for it's heat resistance.

OK, now I just did a GIS on Inconel and Nichrome, and found that they don't seem to be the same, as they are sold side by side. Inconel wire .020 is $12 PER FOOT! while nichrome wire .020 is $2.40 per foot. Inconel better be good stuff