Re: winding a secondary

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

Original poster: "Shaun Epp by way of Terry Fritz <twftesla-at-qwest-dot-net>" <scepp-at-mts-dot-net>

Hello, I just wanted to add a little to this since I am finishing a 4.25" *
22" secondary myself and some of the method I learned were from here :-)
I'm presently on coat # 10 of MinWax, clear gloss polyurethane and its a
time consuming task.  Others on this list have over the past few days shared
that there's a thick quick drying coating available where one or slightly
more coats will do the job and that they were much faster drying,  check out
recent posts on "help with secondary"

What I did to start was to clean the pipe inside and outside with different
cleaners, acetone works well 'cause it removes (mostly) the lettering on the
pipe and really cleans things.  Then I used 120 grit for rough pipe and/or
220 grit after, sand to hole thing.  It will get staticy when sanding, I
thought this was good!  After sanding inside and out, I then wiped it down
with acetone again.

Then drying was done with a small heater, cube heater I think they're
called. I set up the too be secondary inside a a 6" pipe (with standoff  to
lift the secondary off the other pipe) and aimed the heater to blown warm to
hot air down inside the 6" pipe and left it go for a few hours.   Shortly
after that I painted 0n a layer of  poly inside the out.   (this first coat
was messy and I had to sand it down (320 grid) and coat again.

I Then start to wind the next day with a homemade winding jig.  I'm using a
drill as the motor and a variac to control speed.  You also need a freind or
family member to help with this.   BTW keep constant tension on the wire
feed, I found this out the hard way.

After Winding I've read 10 to 15 coats of poly, and as I said earlier Im up
to 10 now.

 between coats, use 400 for rough areas otherwise 600.

This may be overkill but better to much that too little ;-)

All the Best,

Shaun Epp
Winnipeg, Manitoba
Canada

>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