[TCML] Secondary Damage (Large Coil)

[mrapol at frontier.com]

That's an intriguing idea. Thanks for the tip!

PBT


----- Original Message ----- 
From: "Carl Noggle" <cn at q.com>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Sent: Saturday, April 14, 2012 11:04 AM
Subject: Re: [TCML] Secondary Damage (Large Coil)


> Oe way to make a smooth coupling is to drill a small hole through the 
> form, strip the wire ends, and feed them through the hole.  Then twist 
> them together inside the form and solder them.  Then rewind the rest of 
> the coil.  Putting epoxy around the splice couldn't hurt.
>
> The sharp ends will not go into corona inside the form since the field 
> inside is only longitudinal.  I have (unfortunately) made many of these 
> splices and they have all worked well.
>
> ---Carl
>
>
>
>
>
>
>> Hi Amir,
>>
>> Amir Mojarradi wrote:
>>> Hi Bert,
>>>
>>>
>>> That sounds fantastic.
>>>
>>>
>>> Based off of your information, I have a clear idea of the necessary 
>>> steps I will take:
>>>
>>>
>>> 1). Remove bottom winding (~250 turns) - up until the damaged points.
>>
>> OK.
>>
>>> 2). Sand/scrape off the carbonized damage on the coil form
>>
>> OK. If the removed areas leave deep gouges, fill these in with clear 
>> epoxy. After it has hardened, sand the filled-in areas so that they're 
>> flush with the rest of the form before adding the new wire.
>>
>>> 3). Apply thick epoxy resin coat onto the coil form
>>
>> This is not necessary at this stage. Just splice in the new wire and then 
>> rewind the missing portion of the winding.
>>
>>> 4). Splice in a new wire
>>
>> Do this before rewinding - it's much easier to make the splice before 
>> winding the rest of the bottom portion.
>>
>>> 5). Wind new bottom winding
>>
>> OK
>>
>>> 6). Apply thick epoxy resin coat onto the new winding.
>> Coat both the old and new portions of your winding with resin. It will 
>> cover both sections equally well and you'll end up with a complete layer 
>> of protection across your entire winding.
>>
>>>
>>>
>>> Sound all right?
>>> Would you recommend applying the Envirotex over the entire coil, even 
>>> parts which are already coated with several layers of varnish?
>>>
>>>
>>> I'll keep you updated about how the procedure goes.
>>
>> Excellent! As others have mentioned, once you've repaired the secondary, 
>> you may also want to reduce your coupling and re-check the tuning of your 
>> system, since the coating may alter the resonant frequency of your 
>> secondary. Once the system is verified to be in tune, you can try 
>> increasing the coupling. Have s few folks stationed around the coil so 
>> that they can see all sides of the secondary. Run the coil at night or in 
>> a dark room. If you see any evidence of racing sparks, back off the 
>> coupling a bit. Also, look for (and fix) any abnormal corona between the 
>> primary and secondary, such as from the primary tap, between the 
>> innermost primary turn and secondary, or from the strike rail to the 
>> upper portions of the secondary (sort of like a corona "Christmas Tree"). 
>> Corona can quickly grow to become a potentially damaging flashover.
>>
>>>
>>>
>>> Thank you for your kindness,
>>>
>>>
>>> Amir Mojarradi
>>
>> Best wishes and good luck!
>>
>> Bert
>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Bert Hickman<bert.hickman at aquila.net>
>>> To: Tesla Coil Mailing List<tesla at pupman.com>
>>> Sent: Thu, Apr 12, 2012 7:47 pm
>>> Subject: Re: [TCML] Secondary Damage (Large Coil)
>>>
>>>
>>> Hi Amir,
>>>
>>> Many coilers have had excellent results using Envirotex Lite Pour On
>>> High Gloss Finish. This two-part resin is available in many craft and
>>> hardware stores and it can also be ordered through numerous online
>>> sources.
>>>
>>> http://eti-usa.com/envirotex-lite/
>>> http://eti-usa.com/wp-content/uploads/2011/03/Envirotex-Lite-English-Instruction-Sheet1.pdf
>>>
>>> You'll need to set up a well-ventilated, but dust-free (and flying
>>> bug-free!) work area. You will also need to set up a fixture that can
>>> continually rotate the coil form at a surface velocity of ~4 - 5
>>> inches/second. You'll want to apply a relatively thick final coating
>>> (1/16"  - 1/8" max). You'll need apply the resin within ~25 minutes or
>>> less after mixing. You'll need to continuously rotate your secondary
>>> while applying the resin, and then continue rotation until the resin has
>>> sufficiently hardened (typically 6-8 hours) to prevent sagging. Some
>>> excellent practical information can be found in the TCML Archives. Look
>>> for the "Envirotex Lite , High Torque drive" thread in the July, 2009
>>> archives.
>>>
>>> When done right, you'll get a beautiful, hard, crystal-clear coating
>>> that completely imbeds and protects the entire winding. Be sure to allow
>>> your coating to completely harden (2-3 days) before using it in your
>>> system.
>>>
>>> Good luck,
>>>
>>> Bert
>>>
>>> Amir Mojarradi 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 at aquila.net>  To: Tesla Coil Mailing
>>>> List<tesla at pupman.com>  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
>>>
>>>
>>>
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>>>
>>
>>
>>
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