Re: 12" duct 25' , in search of a cheaper, smooth, large toriod

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>

I just use a truck inner tube covered with adhesive aluminium 
tape.  Here is my 9x33 that cost perhaps $20, works great and will never dent.
http://tesladownunder.com/Tesla18inch2nd5ft.JPG
You need to take care to spread the tension of the tape to avoid 
constriction effects.  Also some tape on the innermost diameter needs 
to be placed in reverse so that there is an Al - Al connection to the 
TC without going through adhesive.
After a couple of years it probably needs to be pumped up.

Peter



> Original poster: David Brown <teslaboi@xxxxxxxxx>
>
> Jim,
> I also had a idea on how to smooth-out the duct, by injecting a 
> expanding foam inside and controling the expansion by use-ing small 
> holes drilled on the inside, never had time to try this..
> keep me posted,  I'm looking to make a 12" x  60" Toriod next month 
> for a 12 dia x 48" Tesla Coil.
>
> Dave