Re: Secondary Material, Performance and Price

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Curt,

Agree with Terry here. The last relatively sized 
coil I built was with 8.5" PVC SCH.80. It isn't 
the greatest pvc to use as it's about 1/4" thick, 
but it did the job just fine. Something thinner 
would be a better choice. I've never purchased 
pvc. This 8.5" I found laying in back of the yard 
at work and asked if it was being saved for 
anything. They said "TAKE IT, PLEASE". So, it's now a decent high turn coil!

In my opinion, the former material isn't crucial. 
I've made my best sparks with the worst of 
materials (sonotube). It's cheap, and as long as 
you seal it inside and out with a thinned out 
polyurethane (so that it soaks into the cardboard 
material), it will last forever and will not be 
prone to humidity changes as unsealed forms are 
(and less likely to carbon track). You could make 
a perfectly good coil with a toilet paper roll if 
you wanted to (kind of short however). Just use 
"former common sense" when using whatever form 
you choose. PVC is hygroscopic (absorbs moisture, 
dries out, acclimates to environment). Always 
seal form to prevent drastic environmental 
changes and the coil will always do well, whatever it is.

Take care,
Bart

Tesla list wrote:

> Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi Curt,
>
> Most "normal people" don't use 8" PVC.  But it 
> is common and dirt cheap if you ask plumbers and 
> contractors who throw hundreds/thousands of 
> scrap pieces away every year...  Get a good idea 
> of what you are looking for and start calling 
> around.  I bet someone will be happy to pull 
> some out of the trash to sell you 
> ;-)))  Construction worker friends or just 
> wandering around a big construction site and 
> asking usually works...  Electrical contractors 
> also tend to have plenty of pipe laying around for special stuff...
>
> City water and sewer folks probably throw a few 
> truck loads of odd sections away every month too...
>
> If you do have to buy it, you need to go to real 
> contractor / heavy construction type 
> suppliers.  They may cut it to length for you or 
> just give you a good part of a damaged pipe free...
>
> Once the pipe is cut to say 5 feet, it is often 
> "just trash" they would otherwise have to pay to 
> have hauled off...  Be careful, they may 
> convince you to take a carload home with you and come back for more :o))
>
> Cheers,
>
>         Terry
>
>
> At 10:57 AM 12/4/2005, you wrote:
>
> > Yesterday I naively went out to home depot to buy a
> > chunk of 8" schedule 80 PVC for a secondary coil.
> >
> > I never considered that they wouldn't carry it.  When
> > I go home I did some searching and found that
> > Mcmaster.com sells it in 5' lengths for $89.  Mcmaster
> > also sells 8" Cast acrylic tubes for $192 which
> > doesn't seem all that much more considering the good
> > characteristics I've heard about acrylic (doesn't trap
> > moisture, higher Q, etc.)
> >
> > So my question is, how much SHOULD I expect to pay for
> > a PVC pipe (I suspect Mcmaster is high) and would it
> > be worth the extra $$$ just to go forward with the
> > acrylic?
> >
> > Thanks,
> >
> > Curt.
> >
> >
> >
> >
> > __________________________________________
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