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Re: Toroid Building



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi David,

I got the super flex 15 foot length which is plenty of length for the 8x32 toroid. The Flex Lock seems to only come in 6 foot lengths. What I really wanted was the AL interlocked ducting but the bend radius is way too large (also very expensive). I think because I used the whole length for the toroid, I have less expansion and the surface seems to be fairly rigid and somewhat resistant to dents. My main purpose is to fill the corrigation to get a smooth surface and not necessarily to improve dent resistance. I'm hoping that once the filler is encapsulated in the AL tape, its brittleness will become less of a factor.

Gerry R.

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Gerry,

I haven't really thought about filling in the corrigations of the ducting
with a filler although I am also using McMaster-Carr's 12" ID Super-
Flex extend and compress aluminum ducting that has a compressed length of only 30" but is able to stretch out to 30 ft. maximum length!
It made a nice 12x56 toroid for my "Green Monster" coil system.
This super-flex ducting is a little better than the plain "Flex-Lock"
aluminum duct hose, even when partially extended. Did you use the "super-flex" or the "flex-lock" for your 8x32 toroid? The rea-
son I ask this is that I noticed that the super-flex was noticably
heavier in weight and tougher than the plain flex-lock ducting. I did basically the same thing with my 12x56 toroid that you are talking about doing with yours, except for the filling in of the corrigations. I also simply used a 32" wide x 3/4" thick disc of masonite particle board to "wrap" the duct around to form the toroid and used "Liquid Nails"
construction glue to glue the toroid to the disc. Then, I simply
placed strips of aluminum tape over the whole surface of the toroid
mainly to help make it more resistant to denting. This took a good
half of a day and about 4 rolls of the 50 yard x 2" wide aluminum
tape to cover the massive 12x56 toroid form. I had originally made
a 12x56 toroid out of the plain "flex-lock" but it ended up getting some ugly dents in it and I found the "super-flex" to be somewhat
more durable (5 mil vs 4.4 mil thickness). I think your idea of
filling in the corrigations is a good one if you can deal with the time
consumption involved in constructing it like this as well as the added
weight that this would cause. With an 8x32 toroid, these issues wouldn't be near as accute as they would be with a 12x56 toroid, though. You can see a pic of my old 12x56 toroid, made of the thinner, cheaper "Flex-Lock" ducting covered with aluminum tape
atop my coil at:


http://hot-streamer.com/temp/Rieben/

Click on the first image. I haven't taken any updated photos of
the new toroid yet, but it's the same size as the old one pictured,
only better looking ;^) The single 30 ft extended length of the super-flex ran about $91 from McMaster-Carr and with S&H,
it was still just under $100 total. So including the aluminum tape, I have < $150 total invested in my new 12x56 toroid. Even with the several hours of labor involved in covering the whole
thing with aluminum tape, that seems reasonably economical to
me ;^)


David Rieben

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, August 19, 2005 9:55 AM
Subject: Toroid Building


Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
Hi All,
I'm in the process of making a 8x32 inch toroid using the heavy ducting from McMaster-Carr
I have the toroid formed (ends attached) and I plan to mount an AL disc in the center with a little RTV. I want to fill the corrigations with something that can be easily sanded to make smooth. I am planning on using PLASTER_of_PARIS for this purpose (done after the center disc is mounted for rigidity). After sanding smooth, I plan on sealing the plaster with a varnish and then adding AL tape starting and terminating on the AL disc.
Does anyone see a problem with using the plaster?? Grout is maybe another choice for a filler. Ideas welcomed.
Gerry R.