Re: big secondary coil

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 08:21 AM 9/13/2002 -0600, you wrote:
> >I think Greg Leyh did something like this for Electrum....
>
>Pretty much.  The sonotube was first wrapped with 3mil
>poly however, to provide a mold release.

I was thinking saran wrap or equivalent...



>  The sonotube
>was mounted over a 22' steel arbor, as the paper tube
>by itself was not rigid enough.  A winding jig supported
>the steel arbor on both ends and rotated the tube for
>placing the wire using a 2HP gearmotor.  After fully
>wound, the coilform received a 1" thick fiberglass layup
>using a chopper gun.

Serious thickness then... I suppose though, that your form was physically 
quite large, and you need the inch for mechanical strength.


>After the glass kicked, a router cut two fixed depth
>grooves down the inside of the sonotube, and a pressure
>washer removed most of the sonotube from the inside.
>The mess in the parking lot was substantial.

Indeed.... I'll bet..



> >
> >How would one make a mounting fixture for the secondary?  You could "glass"
> >in a piece of 3/4" plywood in the bottom.  Ideally, one would want to be
> >able to support the secondary horizontally as a cantilever attached only at
> >the base (sort of a worst case...)
>
>Electrum has 1" thick walls in order to support the
>stresses of wind loading up to 150mph.  Lateral struts
>inside the secondary were not possible as they would
>obstruct the central manway.
>Each end of the coilform has a thickened edge, and
>the base end has four steel weldments laid up into
>the fiberglass build.  The weldments support the
>coil tower and anchor it to the concrete vault.

Thanks much...