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

[Finn Hammer <f-h@xxxx>]

All,

Perhaps it all comes down to whether you live in apparently very dry 
Arizona, presumably very damp Florida or- here in Denmark where these 
assumptions were made, and where we have both alternatives interleaved 
on an annular basis.

All my coils had plastic sec`s. PVC, mostly. I abandoned polyethylene 
when the first one was subject to frost and shrunk so much that the 
winding disengaged the thread I`d made for it, and the wire fell down by 
gravity. It was unvarnished.

Cheers, Finn Hammer

Dr.Hankenstein skrev:
> 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
>
> dr.hankenstein@xxxxxxxxxxxxx
> "We put the fire in the wire."
>
>
> > [Original Message]
> > From: <FutureT@xxxxxxx>
> > To: <tesla@xxxxxxxxxx>
> > Date: 12/14/2007 2:29:09 PM
> > Subject: Re: [TCML] Form materials, losses, carbon tracking, sealing
> >
> >  
> > In a message dated 12/14/2007 4:21:41 P.M. US Eastern Standard Time,  
> > btmeehan@xxxxxxxxx writes:
> >
> > > Thanks a lot for the info guys, that helps a lot - I heard someone  mention
> > > using concrete forms.  If I remember, those were made of  very thick
> > > cardboard?  Since I have heard several people talk  about it - I imagine that
> > > it is reasonably resistant to lighting on  fire when it gets strikes?
> > > I had been looking at a model rocketry  site that sells fiberglass forms, and
> > > even does custom work.   Would I be better off with cheaper PVC or concrete
> > > forms, or would the  lower loss tangent of fiberglass be worth something?
> > > (granted, most of  the loss tangent numbers I have seen are in the MHz or GHz
> > > region, so  kHz is probably not a problem with most materials)
> > > (loss  tangents)
> >
> > I would avoid those paper concrete forms.  Some of them have  strange
> > lossy materials in them.  Some are OK though.  Losses in PVC  are
> > not an issue for Tesla coils, but they are subject to carbon  tracking
> > when bad racing sparks or flashovers occur.  Probably the most  common
> > material used for secondary forms is PVC.  Heating and sealing the  PVC
> > is said to be beneficial but I never bothered with those  procedures.  
> > My TT-42, and TT-32 coils both use PVC forms.  
> >  
> >   _http://hometown.aol.com/futuret/page3.html_ 
> > (http://hometown.aol.com/futuret/page3.html) 
> >  
> > John
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > **************************************See AOL's top rated recipes 
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