RE: Water absorbtion of Gray PVC

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi all,
         As someone who (unknowingly) went totally against the grain
when building a coil from untreated sewer pipe back in '93 (yes, it
lives!), I'd just like to add a note to this discussion:

On 8 Dec 2003, at 18:09, Tesla list wrote:

 > 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

In the end, it boils down to just how far you want to push the coil
voltage-wise. A short coil pushed to several hundred kV is naturally
going to need all the help it can get to maintain its integrity. You
can eliminate all the baggage by building a much larger coil so it
doesn't get tested in this fashion. You will likely also get better
results with ease as you boost its inductance, wiresize and
capacitance and lower its frequency. That is the approach I took with
that coil and it worked well. For the record, the secondary is 10"
diameter, about 4' high, has a loathed helical primary and produces
strong hot 5' discharges with just a kW or so of input.

Malcolm
<snip>