Re: Water absorbtion of Gray PVC - sono tube idea

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

Original poster: "pjj" <tha3rdman-at-zoominternet-dot-net> 

Watching discovery the other week ( think it was discovery) they had the
rocket challenge, where the showed how they built the rockets but wrapping
carbon fiber around a sono tube then curing the carbon fiber, and soaking
the whole thing in water to remove the cardboard.

Now at first i though cool a carbon fiber secondary form! but then i though
carbon humm . . .

At any rate why not wrap the mag wire around a sono tube heavily coat as
most do with lacquer or enamel, then remove the card board and wa la AN AIR
CORE.

Just my ramblings
Paul

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, December 09, 2003 9:48 AM
Subject: RE: Water absorbtion of Gray PVC


 > Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com>
 >
 > Hi, I have to agree with Dan here. In all reality a <3Kw coil can easily
 > be wound on un-treated PVC with many years (many hours of total run
 > times) of use. I will add, though, that a quick rough up with a coarse
 > sand paper, and then hitting the coil with a heat gun to get it warm and
 > immediately spraying it with a acrylic sealant, doesn't hurt!
 >
 > Regards,
 >
 > David Trimmell
 >
 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Monday, December 08, 2003 5:09 PM
 > To: tesla-at-pupman-dot-com
 > Subject: RE: Water absorbtion of Gray PVC
 >
 > Original poster: "Mccauley, Daniel H" <daniel.h.mccauley-at-lmco-dot-com>
 >
 >
 > Although your concerns and comments are valid, its really not necessary
 > (especially for the mere hobbyist)
 > to perform this long process of pre-treating a PVC or other hydroscopic
 > forms prior to winding.
 >
 > Although your intent is good, i feel your comments may actually
 > discourage some beginners by making them believe
 > they need to go through this seemingly overwhelming pre-treatment
 > process.  This is especially true considering the
 > comments come from the two most experienced tesla coil firms, Resonance
 > Research Corporation and KVA Effects.  The beginner
 > may believe these firm's comments may hold more water so to speak than
 > the other people on the group.
 >
 > The important points I think should be made are the following:
 >
 > 1.  Yes, hydroscopic secondary forms such as PVC will benefit from a
 > pretreatment process as described below especially
 > in higher power tesla coils (5kW + )
 >
 > 2.  For most small power coils, there is no need to pre-treat the PVC
 > secondary.  This is based on the experience of many of the members of
 > this list including myself.  I'm sure if you took a poll, the number of
 > people on this last that go through the elaborate process of
 > pre-treating a secondary prior to winding will be greatly outweighed by
 > the "just wind it" and go people of the list!
 >
 > Many people on this list will claim sonotube or other cardboard forms
 > are the worst possible material for a secondary form
 > and should be avoided at all costs.  However, the best coils i've ever
 > seen were built with cardboard forms.
 >
 > Dan
 >
 >
 >
 >   > TCML,
 >   >
 >   > I have to back Dr. Rez on this one guys... We use PVC and
 >   > fiberglass forms.
 >   > We have accumulated hundreds of hours of run time on a dozen
 >   > or more PVC
 >   > coils all above 10kW. We have a really burnt PVC form we keep
 >   > in the shop as
 >   > a trophy...
 >   >
 >   > Sand, bake*, seal...
 >   >
 >   > Sanding breaks up the surface. HV arcs love to travel down
 >   > smooth surfaces.
 >   > We use coarse grit and leave the final finish rough. After
 >   > surface prep and
 >   > careful and gradual baking with tungsten strip heater, seal
 >   > the PVC with
 >   > commercial HV varnish. There's more to the process but those
 >   > are the basic
 >   > steps hobbyists should follow.
 >   >
 >   > Will you coil work the same if you don't follow these steps:
 >   > sure! Same
 >   > applies to O-rings and spray-on foam insulation.
 >   >
 >   > * don't over do this step. 20 degrees above ambient for two
 >   > hours is all
 >   > that is necessary IMO. If you use heat lamps, spread them
 >   > out, put them on a
 >   > variac and don't put them too close. "Hydroscopic" doesn't
 >   > mean it's full of
 >   > water and you have to dry it out.
 >   >
 >   > Jeff Parisse
 >   > kVA Effects
 >   > www.teslacoil-dot-com
 >   >
 >   >
 >   >
 >   > snip...
 >   >
 >   > All PVC is hygroscopic especially when used at high
 >   > frequencies. It's best
 >   > to sand interior and exterior, then paint with 3 separate of
 >   > Glyptal or
 >   > other HV insulation. Interior sanding is rapidly accomplished
 >   > by using a
 >   > sanding "flapper" on a dowel (or other extender) on an electric
 > drill.
 >   >
 >   >
 >   >
 >
 >
 >