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Re: [TCML] Secondary Damage (Large Coil)



This stuff works wonderfully and is available at most home improvement stores. One coat easily provides 1/8" or thicker and looks like glass. Make sure you heat with a heat gun immediately after applying to get rid of bubbles from mixing. And plan on keeping your secondary rotating for several hours (6-8 i believe) after installing.
http://www.rustoleum.com/CBGProduct.asp?pid=448

Matthew Edwards

On Apr 12, 2012, at 11:38 AM, Amir Mojarradi <ln2guy42@xxxxxxx> wrote:

> Hi Bert, 
> 
> 
> Thanks for your helpful advice. Is there a particular brand or type of epoxy or polyester that you recommend? I know other forms of epoxy exist, but the only products I have seen at major hardware store are the small,  "5 min" epoxy tubes. Would these be sufficient?
> 
> 
> Thank You, 
> 
> 
> Amir Mojarradi
> 
> 
> 
> -----Original Message-----
> From: Bert Hickman <bert.hickman@xxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Thu, Apr 12, 2012 8:18 am
> Subject: Re: [TCML] Secondary Damage (Large Coil)
> 
> 
> Hi Amir,
> 
> The insulation between turns has been damaged, possibly by a strike to 
> the winding, an arc-over from the primary to the lower part of the 
> secondary, or by handling. Strikes to the secondary can be quite 
> damaging on larger coils such as yours. At the very least you'll need to 
> remove the windings around the affected areas, or remove the bottom 
> portion of the winding since the coil form may now also be carbonized 
> underneath.
> 
> Once the winding has been removed from the affected areas, scrape/sand 
> away any traces of carbonization from the form before applying new wire. 
> Once you have repaired the winding, you may also want to consider 
> applying a thick 2-part polyester or epoxy coating over the winding. 
> This will protect it mechanically as well as helping to prevent any 
> future damage if you get another strike to the secondary. The strike 
> will harmlessly spread out along the surface of the coating instead of 
> destroying the insulation/wire at a single concentrated point.
> 
> Bert
> -- 
> Bert Hickman
> Stoneridge Engineering
> http://www.capturedlightning.com
> ***********************************************************************
> World's source for "Captured Lightning" Lichtenberg Figure sculptures,
> magnetically "shrunken" coins, and scarce/out of print technical books
> ***********************************************************************
> 
> Amir Mojarradi wrote:
>> 
>> Hello Everyone,
>> 
>> 
>> My large secondary coil (12" diameter, 60" in winding length, 18 awg)
>> has repeatedly exhibited overarcing at two specific points. A few
>> months ago, I messaged the list, and decided to thickly re-varnish
>> the damaged areas.
>> 
>> 
>> Unfortunately, the problem has returned at the same two points. Since
>> I am far away from the coil when I run it, I can not precisely
>> determine the cause of the problem. From my research, I can infer two
>> possible explanations.
>> 
>> 
>> 1. Insulation (varnish and wire enamel) is exposed and/or damaged;
>> there is arcing between two turns of the coil. 2. Insulation (varnish
>> and wire enamel) is exposed and/or damaged; there is a premature
>> breakout from a single turn of the coil.
>> 
>> 
>> Below are pictures of the damage, to give a general idea.
>> 
>> 
>> General Reference Image of the Secondary:
>> http://www.flickr.com/photos/teslalightning/7068998821/in/photostream/
>> 
>> 
>> 
>> Damage Point A:
>> http://www.flickr.com/photos/teslalightning/7068998895/in/photostream/
>> 
>> 
>> 
>> Damage Point B:
>> http://www.flickr.com/photos/teslalightning/7068998945/in/photostream/
>> 
>> 
>> 
>> Normal Coil Performance: http://www.youtube.com/watch?v=yjChcjVm5ks
>> 
>> 
>> Any of these causes might necessitate a different solution. I am
>> considering epoxying the damaged areas, using silver conductive epoxy
>> to short out the arc, splicing the wires, or in the most extreme
>> case, to re-wire the coil up to the damaged points and "surgically"
>> soldering them.
>> 
>> 
>> Would using a better insulating layer like Polyurethane or Epoxy
>> help? What can I do besides re-wiring to solve this? Any related
>> suggestions or comments will be extremely helpful, as any solution to
>> this problem will require a meticulous undertaking.
>> 
>> 
>> 
>> 
>> Thank you for your helpfulness and dedication to the hobby of
>> coiling,
>> 
>> 
>> Amir Mojarradi
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> _______________________________________________ Tesla mailing list
>> Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
>> 
>> 
> 
> 
> 
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> 
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