Re: Toroids from Foam

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "cd by way of Terry Fritz <twftesla-at-qwest-dot-net>" <vbprg1-at-hotmail-dot-com>

hey all
I have a friend that uses this foam technique to cut glass
works great leaves a perfect smooth edge.....

I was interested and did a bit of searching the net
a ways back
if you check my links page
http://home.earthlink-dot-net/~cdowdy2/Links.htm
scroll down to hot wire cutting.....

you can find a couple of examples of what a home made hot wire, foam and
glass cutter looks like...

I believe both articles mention using a 12volt battery.
You can use a variac instead....and adjust to the right setting for wire
temperature
also when the wire is heated its expands A Lot... so you need a couple of
bolts
that can be adjusted at least a couple of inches... to compensate for the
heated wire effect....
amount of adjustment depending on the length of wire you plan on cutting
with.

Anyway be carefull have fun...
dont cut foam inside....
 IT STINKS.
Chris

ps I you go to a hobby store dont ask for Nicrome wire
they wont know what the heck it is, ask for replacement wire for a hot wire
foam cutter...
They had that (nicrome wire), and a really junky looking 12v adapter wire
cutter,
some things are just better to make....especially when we all own
variacs....


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, September 06, 2002 9:26 AM
Subject: Re: Toroids from Foam


> Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<sundog-at-timeship-dot-net>
>
> Hi Ted,
>
>    James, Dave, and I used a hot wire saw to cut the 16" discs for the
> massive toroid we made for Dave's big coil.  We used some safety wire and
a
> variac and a LV battery charger to put a few volts across the wire
(doesn't
> take much power at all), and tested it on scrap till we got it up to an
> acceptable cutting temperature.  Too hot and the foam melts a substantial
> distance from the wire as you're cutting it, too cold and it will take
> forever to cut.  You want it hot enough to make a thin, clean cut, and
cool
> enough it doesn't melt a big thick line through your work.  Expect a
*fast*
> cutting rate with most foams. I've had cheap-o foam cut at 2-3 inches per
> *second*.
>
>    My suggestions -
>      Make a jig that resembles a band saw, with a very deep thoat.  Use
> safety wire for the cutting wire (cheap and plentiful).  Secure it at the
> bottom to a loop or eye. Avoid sharp kinks, it gets hotter there.  At the
> top put a spring on the upper arm and attach the wire to the spring.  Make
> sure it's under some tension, because it's gonna stretch when it gets
> hot.  Try some scrap in it till you get the heat setting just right, then
> leave the variac where it is and just unplug it.  Saves the trouble of
> fiddling with the variac.  There is some smell, but it's much easier to
> blow a smell out with a fan than to clean up shreds of foam (which gather
a
> charge and friggin stick to *everything* for a week, and often run from
the
> broom!)  Just don't ask how I know....
>
> Hope it helps!
>
> Shad G5-1203
>
> At 05:46 PM 9/5/02, you wrote:
> >Original poster: "tesla by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> ><tesla-at-paradise-dot-net.nz>
> >
> >Team
> >Has anyone used the hot wire cutting technique to avoid the room filled
with
> >snow effect ?
> >Rgds
> >Ted L in NZ
>
> -----------------------------------------------------------------------
> Shad (Sundog)
> G-5 #1203
> "Ever stop to think, and forget to start again?"
> -----------------------------------------------------------------------
>