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Re: Designing BIG Secondary Coil
Original poster: "Edward Wingate by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ewing7-at-rochester.rr-dot-com>
Tesla list wrote:
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> You can get a variety of large sizes of sonotubes which are a type of
> cardboard / waxed tube used for making cement supports. Just at home depot
> today they had up to 6", 8", 10", 12" and 16" forms. I'm planning on using
> a 10" form. Ed Wingates famous coils typically use these type of tubes for
> coilforms so I am told.
> Plus they are very inexpensive. The last time i went to the plumbing
> distributor, 12" PVC was almost $100.00 a piece (green stuff). A 12" four
> foot long sonotube is only about $6.00.
The coilforms on my 8" and 18" coils as well as the twin coils and my
first magnifier driver are indeed Sonotubes which were coated inside
and out with 3 coats of plain old orange shellac. No special drying
methods were used before applying the shellac. I prefer shellac
because it doesn't dry out and crack like the urethane varnish I've
tried in the past.
My current magnifier driver coilform is polyethylene and the third or
extra coil coilforms , I have a few :^), are PVC.
The bottom line is that I still wouldn't hesitate to use Sonotube if
the other materials either weren't available or were too expensive.
Ed Wingate RATCB