RE: New 4" coil: R.Hull and CSN, Secondary Varnish

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

Original poster: "Jeff W. Parisse by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jparisse-at-teslacoil-dot-com>

TCML,

We use a custom two part epoxy from 3M that sets up with a consistency
similar to that of a "superball" (I may be showing my age here (40) but
do they still make superballs?... It that a valid reference?) Anyway, it
sets up semi-hard but very tough (it's bouncy!), moisture resistant,
rated for HV electrical use and (of course) expensive as heck
($250/gallon kit). 

Given that hardware store brand two part (i.e. not specifically
electrical potting resin) seems to work on small and medium sized coils
(thank you Alan Yang), I'm sure that a local plastics supplier that
supplies two part resins for casting purposes, surfboards, etc. can
either suggest or whip up a softer alternative that's not electrically
rated but nonetheless will still work and be less expensive.

We haven't noticed the "secondary after shock" with the 3M coating
either. My hunch is that the rough micro surface of the semi-hard resin
is less of a capacitor plate (yes I meant plate) than the glass like
surface of hard resin. I'm sure I'm starting a new thread in which I'm
not qualified to contribute so I'll just leave it at that.

Thermal expansion/contraction is rather profound with copper. Got to
keep those windings in place!

Jeff Parisse
www.teslacoil-dot-com


Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

I will definitely second what Charles says here!

Coil forms expand and contract with temperature and seasonal weather.
They can easily shrink enough such that a slight tap will cause all the
loose wire to "fall".  Just a thin coat of spray poly can prevent a
destroyed
coil.   guess how I know all this ;-)