Re: HDPE vs Wood Primary Coil Supports

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>

In a message dated 3/14/03 11:35:21 AM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:


>Hi everyone!
>
>I'm building my second Tesla coil, about 7" secondary
>diameter.
>
>My first coil used HDPE (cutting board) as the primary
>coil support, and it was a pain in the butt to cut
>that stuff accurately and cleanly. I understand that
>it has great RF and high voltage insulation
>properties, making it an ideal dielectric for
>everything from caps to primary mountings, but it
>is expensive and difficult to work with.
>
>I have a more complicated primary coil design for
>my next coil, and I was wondering if anyone here has
>built their primary supports out of wood? I am much
>better at working wood than I am at working plastic,
>but I'm not so sure that wood is a good idea, given
>that all wood contains a certain percentage of water
>and tends to 'kindle' at high temperatures.
>
>I figure that if use some polyethylene varish on the
>wood before mounting the primary into it that it would
>mitigate the water effect. (Assuming that the wood is
>porous enough to absorb the PE)
>
>TIA
>
>Jeremy


Jeremy,

A 7" secondary would imply a reasonable size power supply, like a couple of 
kva or more.  I would not lay or mount the primary directly on wood - even 
varnished, etc. wood.  How about designing it so that you can buy some pvc 
pipe that is the same inside diameter (or close) as the o.d. of your 
primary tubing.  Now cut short pieces like .50" to 1.0" long then cut them 
in half lengthwise.  Now insert these cut pieces into notches in the wood 
forms with the copper tubing laying in them?

Have fun, Ed Sonderman