[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] sealing a cardboard form
Greetings,
I have a 16 inch by 86 inch fiberglass coil (1/8 thick),wound 80 inches
with #14 magnet wire. I used 1 gallon AC-43 to cover,no slippage.
Thats a lot of surface to cover with 1 gallon of slightly thicker
than water ANYTHING.
And 80 inches of #14 is fairly heavy.
I still move the coil around occasionally to different spots"out of
the way"
One of these days I will finish it.Originally I was going to use a 3-4
hundred cap bank,but decided against that.(No way with a 25 kva pig)
This decision was made after already purchasing the caps of course.
A few of the nice gentelman on this forum took care of my excess caps.
I wanted to use a 5 foot sphere as a topload,,the Java model advised
against this.
I have my eye now on a VERY large inner tube (tractor),I do not want,and
will not
use chicken wire.
The AC-43 may not work for others as it did for me,consider:
fiberglass,
cardboard,and most popular PVC. On the other hand consider the bonding
to
magnet wire insulation.I think this engineered bonding is the kicker.
All I am saying is that for MY application the Dolph's seems to do the
trick
Regards
Joe in Texas
On Sat, 25 Jul 2009 23:26 -0700, "DC Cox" <resonance@xxxxxxxxxxxx>
wrote:
> 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
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
--
johnbrooks@xxxxxxxxxxx
--
http://www.fastmail.fm - The professional email service
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla