Power supply for hot wire foam cutter?
Paul N. Cowley
to build him a hot wire foam cutter. I have access to .031" diameter stainless
steel piano wire, but was wondering what voltage/current was used in
commercial models. I have never actually seen one of these in the flesh,
although I _do_ know how they work, etc... and my EE major should help me out
as well. So, gurus! What powers the beast?
Thanks,
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Pete Foss PO/46
Colin Watters
>I have been asked by a friend who flies r/c planes, (as well as rockets... :)
>to build him a hot wire foam cutter. I have access to .031" diameter stainless
>steel piano wire, but was wondering what voltage/current was used in
>commercial models. I have never actually seen one of these in the flesh,
>although I _do_ know how they work, etc... and my EE major should help me out
>as well. So, gurus! What powers the beast?
>
I recently switched to stainless steel wire...
I use a 12V car battery and after experimenting I found the resistance of the
cutting wire (about 1.3M long) was high enough not to need a car headlamp bulb
to drop the voltage.
To answer the question I guess I am operating the wire at 12V at about 4A-5A.
Colin
Richard Soderberg
of wire will vary with material and length but I try various
combinations (keeping a fuse supply at hand) until I get an
acceptable speed of cut without setting fire to the foam/frame/house.
(o o)
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| Email : richard....@mic.ki.se |
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Evil Engineer doin' it the Cowboy Way
to power it with 24 volts just for safety. Plus, it ranges the variac
nicely for a fine adjustment.
For cutting wire, I've been using .015 stranded steel wire (the same I fly
CL models with), on a bow. This wire seems to take slightly less than a
volt per 2 inches to cut either white or blue foam nicely.
Harry Higley has a book called Master Modeling which gives a lot of
valuable information on foam cutting as well.
L.
"Yeh, Buddy.. | la...@psl.nmsu.edu (Larry Cunningham)| _~~_
I've got your COMPUTER! | % Physical Science Laboratory | (O)(-)
Right HERE!!" | New Mexico State University | /..\
(computer THIS!) | Las Cruces, New Mexico, USA 88003 | <>
--------------------------------------------------------------------------
Disclaimer: Opinions expressed here are CORRECT, mine, and not PSLs or NMSUs..
Oh sure, we could do it the _easy_ way. But it just wouldn't be the COWBOY WAY.
Wayne Orwig
> I have been asked by a friend who flies r/c planes, (as well as rockets... :)
> to build him a hot wire foam cutter. I have access to .031" diameter stainless
> steel piano wire, but was wondering what voltage/current was used in
> commercial models. I have never actually seen one of these in the flesh,
> although I _do_ know how they work, etc... and my EE major should help me out
> as well. So, gurus! What powers the beast?
>
> Thanks,
I had scrounged up. Normal voltage probably about 10 with about 5 amps.
This was a while ago so I don't remember exact numbers. If you can make
it adjustable, that can be a real help.
Kim R. Volz
rectifier and an LED. This give an indication of the Heat.
Works well for different foams...pink, blue, gray.
KRV
bl...@inland.com
> I have been asked by a friend who flies r/c planes, (as well as rockets... :)
> to build him a hot wire foam cutter. I have access to .031" diameter stainless
> steel piano wire, but was wondering what voltage/current was used in
> commercial models.
I'd rather not nitpick, but in the interest of accuracy I'm going
to have to correct you. Piano wire by definition is not
stainless steel. "Piano wire" or "music wire" is a highly
engineered and very high strength plain carbon steel. It is made
from the finest quality steel, with a carbon content of
.80-.95 wt%. The wire has tensile strength in the range of
300,000-390,000 psi.
Tofu Peddler
I, too, am wanting to build a foam cutter. I, however, have a small spool of Nichrome
wire. Anybody ever used Nichrome? When you say you use a dimmer switch, what power
supply are you using? The outlet?
Andy Barber
Iskandar Taib
stainless steel wire. If anyone wants a length of this stuff send me
an SASE (email for address) and I'll send a portion off a damaged set
of combat lines..
The power supply I use is a Variac, or auto-transformer. The one I use
is rated at 10A and it doesn't even raise a sweat. Its usually set to
14 volts for a 27 inch bow. They aren't too expensive if you know
where to go. I've seen various other power sources, including one
involving a lightbulb and a light dimmer switch in series. An iso-
lation transformer between that and the hot wire should make things
safer too.
I'll post a couple sources for Variacs. Another thing I've used in the
past was an 18V 2A transformer, but I was using nichrome at the time.
See the Caudimordax article in the December 1990 issue of Model
Aviation.
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Iskandar Taib
>In article 10...@amc.com, k...@amc.com (Kim R. Volz) writes:
>>I use a dimmer switch. If you want to get fancy add a small neon bulb or a
>>rectifier and an LED. This give an indication of the Heat.
>>
>>Works well for different foams...pink, blue, gray.
A couple words of warning here. Some foams (particularly the poly-
urethane ones) release harmful gases when melted. Even the extruded
polystyrenes (DOW Foamular or DuPont Styrofoam(tm)) release methylene
chloride gas, which is liberated from the pores.
Even when cutting plain old white beadboard it is a good idea to have
good insulation. No knowing what styrene monomer does to people...
>I, too, am wanting to build a foam cutter. I, however, have a small spool of Nichrome
>wire. Anybody ever used Nichrome? When you say you use a dimmer switch, what power
>supply are you using? The outlet?
Nichrome sucks. If you stretch it too tight it will break, and you do
want as tight a bow as you can get. Use stainless steel wire.
Iskandar Taib
>Even when cutting plain old white beadboard it is a good idea to have
>good insulation. No knowing what styrene monomer does to people...
Ventilation! Ventilation!!
Argh..
Iskandar Taib
H&R (Herbach and Rademan) Company
18 Canal Street
P.O. Box 122
Bristol, PA 19007-0122
Staco brand Variacs
Output Price
0-132V 1.75A $45
0-132V 2.0 A $46
0-132V 2.25A $47
0-132V 3.0A $53
0-140V 5.0A $84
0-140V 10.0A $104
GE Voltpack (wall mount)
0-50V 5.0A $24.50
(The last looks like a really good deal for cutting foam, but has to
be assembled/mounted)