DC -
I think you may not have read this entire email string. One poster
suggested evaluating a secondary coating material that may not
have been previously tried; a responder questioned whether it was
worth the "risk" to evaluate anything new or untried, since
suitable coating materials are already known.
My point was to ENCOURAGE experimentation and evaluation of new
materials and processes, accepting the fact that the path to a
significant success may be paved with minor failures.
Additionally, I questioned whether there was any reliable test
data that conclusively showed Dolph's AC-43 to be any better FOR
INSULATING TESLA COIL SECONDARYS than less expensive, more
commonly used, and more readily available coatings.
Are you able to provide any such test data that would show the
superiority of AC-43? If not, there's no shame, just say that you
have no supporting data. Perhaps someone else may be able to take
the time to perform controlled experiments that could yield useful
data.
My only caution about using Dolph's AC-43 as a coating for Tesla
coil secondary coils is the fact that it contains up to 25% by
weight of xylene, a very aggressive aeromatic solvent. Any Tesla
coil secondary wound on a plastic former (PVC pipe, acrylic or
polycarbonate tube, etc) is at risk of solvent-induced cracking or
crazing caused by exposure to the xylene. Cardboard forms would
not be at risk.
Remember that Dolph's AC-43 is designed specifically for
impregnating motor and transformer windings, which (aside from
Nylon coil bobbins) don't contain the types of plastics most
commonly used for secondary coil forms in Tesla coils.
If you'd like to "help" Tesla coil builders on this forum, why not
provide data that would help support some of your claims for
"performance enhancement"? Like the silver-plated secondary wire:
Is there any DATA to back this up, or just an opinion, along with
the observation that Tesla coils built with silver-plated wire can
produce sparks. Or Dolph's AC-43; is there any data showing that
this is "the best" possible coating, or is this just an opinion,
along with the observation that tesla coils built with Dolph's can
produce sparks?
I think Terry Fritz started a real revolution in Tesla coil design
and construction years ago when he tried to get everyone thinking
in terms of analyzing real data, and not just relying on
tradition, word-of-mouth, or what happened to work well on one
coil, without understanding the underlying reasons WHY something
worked.
I think Terry's approach to analyzing and understanding Tesla
coils has proven itself over and over.
Regards,
Herr Zapp
--- On Sat, 7/25/09, DC Cox <resonance@xxxxxxxxxxxx> wrote:
From: DC Cox <resonance@xxxxxxxxxxxx>
Subject: Re: [TCML] sealing a cardboard form
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Saturday, July 25, 2009, 11:26 PM
Certainly, there are definitely alternatives. Polyurethane will
flake off
especially if it is subjected to any heating/cooling cycles.
Epoxies are
great if you get the mixture perfect, if not, sometimes they never
completely cure and remain tacky.
I've built approx 250 coils using AC-43, some in operation for
over 30 years
without any breakdown.
You also have to consider it's used on HV transformers, approx 250
built on
a daily basis in USA.
Their industry wide reputation is such that it not questionable,
just solid
engineering. It's used by over 70 transformer manufacturers in
the USA
alone. Perhaps many more worldwide.
If you need further proof, just call Dolph's and they will email
you the
engineering data.
Yes, someone certainly could do the work of winding several coils,
then test
them for breakdown, but this usually requires time and money. Also,
expensive test instruments
to make the correct measurements in a precise fashion.
As usual, your "suspicions" are out of line, and certainly not in
the spirit
of this forum. I try to help experimenters, not be overly
critical of their
work or efforts.
Dr. Resonance
On Sat, Jul 25, 2009 at 1:39 PM, <quarkster@xxxxxxx> wrote:
Dave -
I would venture an educated guess that very, VERY few Tesla coils
have
actually been built using the expensive Dolf''s varnish as a
secondary
overcoat. Based on closely monitoring this list for nearly ten
years,
attending a fair number of Teslathons, and coresponding with
scores of TC
builders over the years, I estimate that for operating amateur-
built TC's of
all sizes, the "real numbers" for secondary overcoatings may look
something
like this:
1. No secondary overcoating at all;
2. Clear varnishes of all types, including oil and water base
types (most
commonly polyurethane, but also good old fashoned marine spar
varnish, etc);
3. Two-part epoxy materials;
4. Dolph's AC-43, "Glyptal", and other types of commercially-
sold "corona
dope" insulating coatings.
I think that a very interesting experiment would be to wind at
least 5
identical secondary coils, coat 4 of them with the most commonly
used
insulating material, and then subject them to ever-increasing
electrical
stress in a large bang-size coil, gradually increasing coupling
until
insulation failure (racing sparks, turn-turn arcing, etc.) occurs.
I'm strong proponent of evaluating new processes and materials in
an
attempt to improve the technology. Successful evaluation means
pushing
the stress levels to the threshold of failure, and beyond. If
someone is
willing to take the time to evaluate new "stuff", and understands
that this
unavoidably includes the risk of failure, then let's not dissuade
them from
trying.
If a small-to-medium size secondary fails this testing, what's
the cost? At
max, $20 or so of magnet wire, $10 worth of PVC pipe, and a few
hours of
labor, it's not terribly significant.
If DC Cox (or anyone else) has spent lots of time and money
functionally
evaluating multiple kinds of other secondary insulating materials
before
finally selecting Dolph's AC-43 as the very best, then I invite
him to share
this interesting and useful data with the TCML.
Personally, I suspect that DC read some Dolph's advertising
claiming that
it was "good for high voltage applications", found that he could
make a
profit by re-packaging and re-selling this product at a markup,
and thereby
claims that it is "the best material" for insulating TC
secondary coils.
If there really IS comparative test data, developed under
controlled
conditions, that shows the clear superiority of Dolph's for this
specific
application, then let's see it.
I happen to prefer two-part epoxy for coating secondary coils,
and I have a
number of very specific reasons for this preference (that I have
shared with
the TCML over the years through several detailed posts). However,
I do not
have side-by-side test data comparing epoxy with other materials,
so I
cannot prove it's superiority on all possible evaluation
criteria. And no, I
don't sell any epoxy coatings of any kind.
Regards,
Herr Zapp
--- On Fri, 7/24/09, Dave Halliday <dh@xxxxxxxxxxxxxx> wrote:
From: Dave Halliday <dh@xxxxxxxxxxxxxx>
Subject: RE: [TCML] sealing a cardboard form
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Date: Friday, July 24, 2009, 11:19 PM
A couple of comments inline:
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx
[mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of PAUL THOMPSON
Sent: Friday, July 24, 2009 3:36 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] sealing a cardboard form
----- Original Message -----
From: "DC Cox" <resonance@xxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, July 24, 2009 4:20 PM
Subject: Re: [TCML] sealing a cardboard form
A Tesla coil secondary coilform is subjected to very high
potential
stresses. Why not just use a product especially developed
to seal high
voltage transformer windings?
Because improvisation and learning is why I do this. If I
want a perfect
secondary, I can buy one. But why bother?
How many hours do you want to spend to find out that your 'great
idea' was
an engineering rathole and that your time and materials have been
wasted.
There are a lot of people offering advice here and the reason
that people
keep coming back to specific things is that they have been tested
by the
community and have been found to work the best.
MMC's, specific coatings, designs for spark gaps, etc...
Dolph's AC-43 is one such liquid especially designed with
high dielectric
resistance, and anti-tracking properties.
Do you sell this stuff or what?
He probably does but I would doubt that he makes a lot of money
off of it.
This is especially a factor considering just how many gallons of
other
paints / varnishes / coatings / etc... he probably tried out
before he
found
that Dolph's worked the best.
I would hate to see the number of 5-gallon tubs of very expensive
stuff he
has with just a couple pints taken out and a faint "Oh Snap!"
still hanging
in the air.
You certainly can take a chance with other products, but if
they don't do
the job then you have to completely replaced the coilform
and rewind the
coil.
We learn by doing.
Or by watching other people doing the same thing and learning
from their
mistakes.
Set RANT=off
Cheers!
Dave
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