Original poster: "resonance" <resonance@xxxxxxxxxxxx>
I still think the mesh toroid method is the way to go. I have made
several 8 x 30 and 60 x 16 toroids in this fashion. When finished
we spray them with black conductive paint. They work great for
larger and even medium size coils that you intend to pump a lot of
power into. I will send the fabrication photo details to Terry and
perhaps he can post them in the archives section for your viewing.
http://hot-streamer.com/temp/DC_Cox/
An 8 x 30 size costs approx $125 to fabricate plus two days of your
time. They work great --- you will see them run on our large coils
at our Teslathon next week.
Dr. Resonance
Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>
Jim -
I found Rubber-Cal/Ducting.com in Santa Ana, CA about two years
ago, and stopped in one afternoon. They are primarily a distributor
of industrial hose, and do not stock much duct material that would
be useful for toroid fabrication. They do have an interesting
sample shelf with 1' sections of a lot of different duct & hose
products. Before getting excited, look at the pricing; its
outrageous, in my opinion.
Another option is the convoluted stainless-steel duct material used
as chimney liners in the Midwest & East-coast areas. (search the
web for "chimney liner"). It doesn't seem to be widely used on the
West coast. Its available in several different stainless-steel
alloys, in sizes from 3" OD to 16" OD. I think all this stainless
steel duct material is manufactured by only one or two sources, and
sold for different end uses.
I obtained a 6-foot long section of 6" diameter duct, fabricated
from alloy 316, to evaluate its use in damage-resistant toroids.
First off, it is truly crush-proof and dent-proof. I think it would
easily survive all the drops and knocks that quickly turn an
aluminum duct toroid into junk. Whereas the convoluted aluminum
ducting is fabricated from extremely soft alloy, the stainless
steel material is thicker and MUCH, MUCH harder & stiffer. I don't
know if the stainless steel strip starts off as half-hard material,
or just work-hardens during fabrication, but it ends up being like
a huge spring. Its intended use is for basically straight runs
lining a brick or masonry chimney. Trying to form it into a torus
of reasonable diameter is almost impossible, at least with the 6"
diameter material. Larger diameters would be likely be even worse.
First, you'd need a piece at least 1.5X or 2X longer than needed to
form the actual toroid to allow you to form a 1-1/2 turn helix. The
material is so stiff that you can't form the "ends" into a radius,
they just stick out straight. You'd need to form the 1-1/2 turn
helix, cut the straight "ends" off, and then try to find some way
to flatten out the helix so the cut ends could be aligned and
joined to form a torus. The joining process would also take some
ingenuity, as the material is too thin to TIG weld, so some sort of
insert would probably need to be fabricated to align and secure the open ends.
Bottom line is that the stainless-steel duct material itself looks
promising, but the process for converting a length of this stuff
into a presentable toroid needs to be worked out. I just haven't
had enough free time to develop the fabrication process, so my
ducting still sits in a big box gathering dust......
Regards,
Scott Hanson