Re: winding the secondary

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Jeff,

If the pipe is new and has no weathered/oxide coating, simply wash/wipe off
all dirt both inside and out, sand off any lettering or striping (which, if
black, may tend to be somewhat conductive), let it thoroughly dry, then
seal if desired using clear polyurethane. If the pipe is older and
weathered, you may want to sand off the outer chalky coating since this is
porous and absorbs water. Minor scratches and nicks should not hurt
anything, but don't use the pipe if it has holes in it (such as some
drainage pipe) or is cracked, since this may result in internal flashovers. 

If you have any deep gouges that will be parallel with the secondary
winding, you might want to fill these with a nonconductive caulk such as
clear silicone to improve outer appearance. Baking is not necessary for PVC
coilforms. Coating after winding helps secure the windings with temperature
changes, and a thicker coating helps distribute voltage stresses somewhat
as well as providing mechanical protection for the windings. 

Good luck on your coil!

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "Janet Johnson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jpjmassage-at-earthlink-dot-net>
> 
> Hi list,
> I am getting ready to wind my secondary and I have been reading different
> approaches.  Brent Turner's book says if you use a plastic (PVC) pipe, just
> sand it and clean it, wind it and seal it with "several light coats of a
spray
> acrylic or lacquer."  So he doesn't say it's necessary to seal it before
> winding it.  Richard Quick on the other hand, says to bake it in an oven
> overnight after wet sanding it and then coat it with polyurethane for several
> hours before winding it.  My questions: if you just dry sand the pvc do you
> need to worry about drying it?  How smooth does it need to be (I haven't
gotten
> all the scratches and nicks out of it after sanding it quite a lot)?  Do you
> coat it again after winding?
> Thanks for your time...
> Jeff Johnson