Re: [TCML] I think I ruined my 6" secondary.

[Yurtle Turtle <yurtle_t@xxxxxxxxx>]

Comments interspersed:

--- On Sat, 7/5/08, Quarkster <quarkster@xxxxxxx> wrote:

> From: Quarkster <quarkster@xxxxxxx>
> Subject: Re: [TCML] I think I ruined my 6" secondary.
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Saturday, July 5, 2008, 9:04 PM
> Adam -
>    
>   Possibly you misunderstood the two points I was trying to
> make:
>    

I just wanted to understand all the variables involved. 

>   2. The bond failure between the Behr-50 epoxy coating and
> the magnet wire material (as it was described by the
> original writer) was an adhesion failure between the epoxy
> and the coating. There was no information provided that
> would support a conclusion that the epoxy had become
> "brittle" over time.

I don't know what you mean by "an adhesion failure between the epoxy
and the coating". And I thought the original poster clearly said the epoxy (if that's what Behr 50 is) got brittle with age.

>   There are many different types of insulation used on
> magnet wire, and some may not be capable of developing a
> good mechanical bond with any type of secondary coating. I
> suspect that some of the insulation formulations containing
> nylon (polyurethane-nylon and polyester-nylon) may not
> develop a good bond.

Precisely why we need more details. Details such as, did the epoxy let go of the wire or the form or both? What was the form material and how thick (rigid) was it?

>   I'm not sure what the size of a secondary has to do
> with either of these topics. I have wound and epoxy coated
> larger forms (12" dia) with larger magnet wire (#17
> AWG), but this was not actually a TC secondary.
>    

The circumference of two different materials that expand and contract at different rates can make a big difference as the size goes up. What type of form was your 12" coil? PVC or cardboard? Did you use Behr 50 or something else? Did you store it in your garage or in a climate controlled environment? My garage sees temps as high as 95 degrees and as low as freezing, with a wide variety of humidities. To date, I've only used spar varnish, but am considering epoxy on my next 16" coil. I don't want to use something that ain't up to the task, but I also don't want to rule epoxy out prematurely.

>   Regards,
>   Herr Zapp

Adam


      
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