On Wed, 20 Nov 2013 07:23:58 -0800 (PST), firstname.lastname@example.org wrote:
I haven't tried this on styrofoam. I bought new a heater element,
metal covered covered tube, 1/4 or so inches in diameter,, 10 inches
long, runs on 110AC. I've used it to bend lucite or lexan, narrower
than the heater is long. Mine is not that hot, although I've never
But if you got a toaster oven out of the trash, each element runs on
110-120VAC and many/most brands are not just the coiled wire, but they
are some sort of glass or metal. tube. It might cut styrofoam well,
or not, or maybe it will be too slow. Worth a little upfront, then
you'd always be able to do so.
They sell the elements new too, I'm sure.
I think they get hotter than the one I have, or maybe it just seems
that way because there are 4 of them on the top and 4 on the bottom
(or 2 and 2)
A regular toaster (for bread and such) has bare, metal bands that are
straight for, I guess, 6 inches. Other than figuring out how to make
it work without burning something up, this would appear to be an
ideal place to start. Though, some older toaster ovens have the same
set up and might provide longer lengths of the bands. Its just a matter
of holding one in place without a shock/fire hazard, and after measuring
the resistance of the entire device, replicate that resistance via
high wattage dimmer switch and maybe a few power resistors or maybe
even some form of DC feed instead of AC with a resistance adjusted for
the DC voltage. More of an electronics question at that point.
I did, when I worked at a govt resarch lab. Hadda make several
shipping containers lined with various sizes of polyethyline foam
insulation. I made a 3-1/2 ft deep hot wire cutter scroll saw type
cutter using chromium wire and a variac. Strung the wire across two
pieces of shelving rails bolted together to make the scroll saw frame,
hooked wire to a AC variac, and turned it up till the wire got hot
enough. Worked perfectly and we cut all sheets of foam in 1 day,
which woulda taken several days by any other method. Granted, we had
access to the worlds greatest govt hardware store, yet this crude idea
worked perfectly. Basically only need an AC variac and some chromium
wire and a few insulators. You can knock out the scroll saw frame
from most anything.
bob haller;3152461 Wrote:
> dont forget insulation like this is VEY FLAMMABLE, and should be
> completely covered by dry wall or a minor spark could start a major
A minor spark could start a fire?
Bob, I'll concede that polystyrene is flammable, but if you've ever
tried to burn the stuff you'll realized it's kinda hard to get it
burning. It melts and pulls away from the source of heat.
If it was as flammable as you're suggesting, it wouldn't be used as
insulation in virtually all of the flat roofs on the continent.
The 3.5 year old OP did say it was a shop. Things in shops sometimes make
I'm not saying drywall on a garage door isn't worth shaking your head over,
but the warning itself has (some) merit. The suggested solution, well, not
so much. ;-)
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