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Re: Big Toroids, collective conscious brain storm
Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
At 03:00 PM 9/12/2006, Tesla list wrote:
Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>
Several different fabrication processes COULD be used for
fabricating toroids, but only a few would be realistic candidates
for the low-volumes of Tesla-coil enthusiasts. Some of these processes are:
1. Roto-molding:
2. Blow molding:
3. Vacuum-forming I think the best candidate fabrication process for
toroids in the sizes we are interested in, and in realistic
quantities, is vacuum-forming. In this process, a sheet of
thermoplastic is supported in a frame, and then heated by infra-red
lamps or overhead gas burners until it is quite soft. T
Of course this takes a fairly large machine, but it is quite simple
and (theoretically) could be home-made using aluminum or steel
angle-iron, banks of infra-red heating lamps, and a "cheap"
vane-type vacuum pump along with a big vacuum reservoir.
A vacuum cleaner will provide more than enough force.
But consider this. Since you're going to be seaming around the
"equator" anyway, why not vacuform octants (i.e. quadrants of a
toroid). A 2x2 foot piece of plastic is quite reasonable to handle.
A good friend of mine has a large vacuum-forming system that is used
primarily to form aircraft parts (interior panels, etc), and I have
watched this system in use over the years fabricating many different
types and sizes of parts from different types of plastic sheet.
In fact, you could probably find a local place that would be happy to
make the "buck" that is the form (made from wood, so it's something
that is home fabricatable) and to zap out endless quantities of
untrimmed panels. You would be responsible for trimming the panels
and gluing it up.
You could easily put a small "lip" on the edges to make the joining easy.
4. Yet another process that could be used is vacuum-bagging.
This process is extremely simple from a tooling aspect, but is very
labor intensive and really requires a lot of experience to get good
results. It is as much an "art" as technology.
Very very much..
I have talked to my friend previously about forming some prototype
toroids using either his vacuum-forming or vacuum-bagging setup, but
just have not had the time to follow up. Some of his vacuum-bagged
aircraft parts have to withstand lightning-strike testing, with a
fairly high level of electrical conductivity, so I'll check to see
what the material options are. It would be very nice to see a
lightweight, absolutely dent-proof, reasonably-priced black
carbon-fiber composite toroid that was conductive enough for Tesla
coil topload use without requiring an external conductive coating.
Or a vacuum-formed ABS or polycarbonate toroid that was equally-dent
proof, either covered with aluminum tape or sprayed with conductive
nickel-based EMI shielding paint.
I'd go ABS or styrene.. easy to glue, not brittle (if you pick the
right material and filler) cheap
and figure out someway to apply a conductive coating.
Regards,
Scott Hanson