PVC DUCT PIPE - ONLINE ORDERING: Was Re: big secondary coil

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


 Actually, Robert, Greg built his a long time ago (in TCML terms).. I'm the
> one looking for good ideas now.
>
> I called my local pipe supplier, but large diameter( >16") plastic pipe is
> pretty pricey (hundreds of dollars for 3 8 foot pieces) even for "non
> pressure rated" SDR.  I haven't checked pricing on PVC ducting, which has
> thinner walls and might be cheaper.


If you are interested in PVC Duct pipe,
www.usplastic-dot-com  sells PVC Duct pipe up to 24" in diameter in 10 foot
standard lengths and will deliver.

24" - $390 for 10 foot length
20" - $280 for 10 foot length
18" - $300 for 10 foot length
16" - $220 for 10 foot length
14" - $191 for 10 foot length
12" - $150 for 10 foot length

It still is pretty expensive, but for large coils, the price for this type
of secondary is probably only a very small fraction of what the total cost
of such a large coil is.

Dan




Also, that pipe gets pretty heavy, even
> in thin wall.  A single or two plys of fiberglass is going to be striffer
> and lighter than bulk PVC.
>
> The sonotube is just a cheap circular form.
>
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Saturday, September 14, 2002 1:22 PM
> Subject: Re: big secondary coil
>
>
> > Original poster: "robert heidlebaugh by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-desertgate-dot-com>
> >
> > Greg: I buy white PVC pipe from 1" thick down to 1/4" thick and from
5/8"
> to
> > 42" dia so playing with sono tube seams a waste of time, but if you must
> > pull a tight layer of sheet polyethylene over it before you plastic coat
> so
> > the fiberglass wont stick. Phone your local irrigation supplier first.
> >    Robert  H
> >
> > > From: "Tesla list" <tesla-at-pupman-dot-com>
> > > Date: Fri, 13 Sep 2002 08:21:11 -0600
> > > To: tesla-at-pupman-dot-com
> > > Subject: Re: big secondary coil
> > > Resent-From: tesla-at-pupman-dot-com
> > > Resent-Date: Fri, 13 Sep 2002 08:35:33 -0600
> > >
> > > Original poster: "Greg Leyh by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> > > <lod-at-pacbell-dot-net>
> > >
> > >
> > >> Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
> > >>
> > >> Casting about for ideas on inexpensive, but high performance, forms
for
> a
> > >> secondary around 18" (50 cm) in diameter and 6 ft (2 m) long...
> > >> [snip]
> > >> But, what about taking the sonotube, putting 1 or 2 layers of
> > >> fiberglass/resin composite over it (or, you don't even need glass,
you
> > >> could just use canvas as the fiber).. wait for it to cure (at least
to
> the
> > >> "tacky" stage).
> > >>
> > >> Wind your coil.  Fix the windings with something (another layer of
> glass?..
> > >> urethane? glyptal?, etc)...
> > >>
> > >> Remove the sonotube by scoring and water soaking it.
> > >>
> > >> 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.  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.
> > > 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.
> > >
> > >
> > >> Questions:
> > >>
> > >> How much fiberglass on the inside?  The windings themselves will
> provide a
> > >> fair amount of strength. For more longitudinal strength, one could
put
> some
> > >> sort of insulating beams on the inside (fiberglass tubing or PVC
pipe)
> > >>
> > >> 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.
> > >
> > >
> > > -GL
> > >
> > >
> > >
> >
> >
> >
>
>
>
>
>
>
>