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Re: [TCML] sealing a cardboard form
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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