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Re: [TCML] Form materials, losses, carbon tracking, sealing



Has anybody ever tried building a coil on a cardboard form, applying 
many, many coats of thick urethane or epoxy or whatever, and then 
removing the cardboard form alltogether?  From what I understand of the 
sonotube cardboard forms, they are meant to peel off once the concrete 
is dry, so would it be possible to have a very delicate formless coil if 
great care was exercised during it's construction.  Please note, I do 
not consider myself careful enough to try this, I am simply curious to 
see if anybody else did.

Scott Bogard.

Lau, Gary wrote:
> I think it was someone else who noted a failure on a new PVC secondary, and failure analysis showed that there was something embedded within the plastic. I think it may have been Terry that investigated the contents of PVC forms, but not certain.  If one takes a piece of relatively thin wall PVC pipe (4" SDR) and you put a light bulb inside, it's easy to see bits of flotsam and jetsam.
>
> As a separate issue, Terry performed a "ping" test to investigate secondary properties, and found that secondary coils wound on paper concrete forms were significantly lossier than PVC forms.  But the experience of many suggests that at least for spark-gap coils, concrete forms do work, perhaps because when using a pole pig for power, the losses in the form are small by comparison.  I think I recall some say that when used for CW coils, tube or solid state, that the losses in concrete forms do become a problem.  Not sure about disruptive DRSSTC's, but probably best to stick to PVC there.
>
> Regards, Gary Lau
> MA, USA
>
>   
>> -----Original Message-----
>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
>> Behalf Of Barton B. Anderson
>> Sent: Friday, December 14, 2007 8:51 PM
>> To: Tesla Coil Mailing List
>> Subject: Re: [TCML] Form materials, losses, carbon tracking, sealing
>>
>> It's not the ink but the particles that become embedded within the paper
>> (metallic particles) when it's made. I think Terry Fritz did a study on
>> this to find areas of metal clumps within the cardboard. Obviously,
>> moisture absorption is high so sealing is certainly recommended.
>>
>> I personally haven't had any noticeable problem with paper concrete
>> forms, but I can understand the apprehension. What I don't like about
>> the forms is end cap mounting. Also, if it falls it's easily damaged
>> (like when your wife opens the garage door and the back of the door hits
>> the top of the coil! Yes, I know, my fault).
>>
>> Take care,
>> Bart
>>
>>
>>
>> Dr.Hankenstein wrote:
>>     
>>> I'm not so sure if using paper concrete forms is such a bad idea if you take care
>>>       
>> to make a careful selection and remove the "inked" layer, properly dry and varnish
>> the form. For example, here is a picture of a 12" by 48" coil built by Dr. Spark
>> producing about a 8 foot spark. This coil uses a cement form and has produced
>> arcs in excess or 14 feet with no problem!
>>     
>>> http://www.drspark.org/images/wwt2007/1281.JPG
>>>
>>> Spark on!
>>>
>>> Woo
>>>
>>>       
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>>     
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
>
>   


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