Re: Small toroids

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

Original poster: "Ed Phillips by way of Terry Fritz <teslalist-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
 >
 > Original poster: "John Richardson by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <jprich-at-up-dot-net>
 >
 > Hi Everyone,
 >
 > Has anyone out there made toroids as small as 8"OD from 3" drier duct?  I
 > have spent half of the afternoon trying to fashion a decent joint, and
 > after failing to join the two decently, decided to make the joint with
 > masking tape, figuring I could cover the whole thing with aluminum tape
 > anyhow.  I have already wasted a roll of tape trying to make a smooth
 > surface, and I am very close to jumping on the whole darn thing.  Any ideas
 > on how to make a decent splice without covering the toroid with tape, or
 > how can I get a decent finish if I do tape it?
 >
 > Thanks,
 > John Richardson
 > (One grumpy toroid maker!)

	I haven't made one quite that small, but have made several using the 3"
duct.  I did as you did, used masking tape to make the joint and then
wrapped several layers of masking tape on the duct until I got a
reasonably smooth surface.  Seemed to take at least 4 or 5 layers.
After that I wrapped on the aluminum tape, burnishing it with the bowl
of a spoon as I went along.  With your size the hole in the center may
be too small to get a decent job.  Why not make it bigger?

	My nephew teaches an advanced science course at a high school for
gifted children, and his classes have made several beautiful terminals
from 3" and 4" flex duct.  Guess they had more patience than I do.  They
also built a twin coil which gave about 6 foot arcs when using several
12 kV, 60 ma NST's in parallel.  After a sales pitch by the nephew, they
got those for nothing by taking apart old signs behind a sign shop.

Ed