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Coil Repair Effort

Subject:  Coil Repair Effort
  Date:   Wed, 11 Jun 1997 21:04:13 -0500
  From:   Chuck Curran <ccurran-at-execpc-dot-com>
    To:   Tesla List <tesla-at-pupman-dot-com>


Hello All:

I just finished a few hours of repair work on my newest coil, which I
test ran about ten days ago.  The secondary repair turned out to be
easier than I had anticipated, where I had to replace the damage caused
by the shorted turns.  I was able to lay in the same number of turns
that I cut out, however the soldered connection points do bulge up
beyond the nominal diameter of the rest of the coil.  I did cover the
joints with a pretty thick "glob" ( technical Engineering term) of
epoxy, resulting in two nice warts on the O.D.  I believe Richard Hull
had described a similar situation with his last big two coil system. 
This will probably be the first of many "Warts" my coil grows, as I
learn from my mistakes!  Right now I am a bit concerned as to whether or
not the bulges will actually promote arcs or not--I'll soon find out.

Just to balance the work out, it appears that my vacuum gap took a bit
more abuse than I had originally realized.  Since the secondary took
less work, it's only fair that the gap will take more than I thought! 
My design was faulty in that I used full diameter rods from top to
bottom.  The arcs tended to end up near the ends, which were in direct
contact with the 1/2" thick acrylic box that supports and insulates the
nine 1' diameter by 3" long electrodes(See attached picture).  The
result was that the arc heat melted away ah, divots so to speak into the
arcylic, about 1/8" deep by 3/16" wide by about 3/8" long.  Lots of nice
black carbon is left over too.  The new design for the brass electodes
will use a 30 degree by 1/16" chamfer so the rod end will be 7/8" in
diameter forcing the arc to take place at a point quite a distance from
the acrylic plates---I hope.  I'll do that tomorrow and be able to
reassemble things on Friday.  Testing again over the weekend, if I'm
lucky I'll be able to get closer to a better tune.

I hope not to be an active participant in the Maximum smoke contest  RW
will be the winner.

Chuck Curran
Cedarburg, WI