RE: bulkheads / baffles in secondaries

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Original poster: "Garry Freemyer" <garryfre@xxxxxxxxxxx>

I have put baffles in my coils. I have had one of them fail too. The baffle
was made up of a plastic cup but the ozone caused the cup to crack and decay
allowing sparks through.

Also, using silicone seal to seal any gaps seemed not to work well, as the
one that failed not only had cracks well away from the failure point, the
primary had a 15 inch burn track that lead between the silicone seal and the
inside of the pvc itself! Seems that silicone seal does not always make
enough contact with the inside of the tube to form a good barrier.

Holes left unsealed in the baffles would defeat the purpose of the baffles.
Vent holes in the tube might provide a path for sparking if there were holes
on both sides of the baffles.

The best result I have gotten using baffles is to get flat end caps for the
tubing and remove the rims so that they fit snugly inside, and then seal it
up with epoxy or some other non-flammable glue that is quick setting. Once
the glue is set and stops emitting vapors, the tube can be closed up.

So far, the end caps also seem to be tight fitting enough to overcome the
problems with silicone seal having to be pressed hard against the inside of
the tube to ensure a good seal.

You might be able to cope with the holes left in the baffles by the shaft of
your lathe if you had them placed close to the end where you could cover
over and seal the holes after winding.



-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Tuesday, August 15, 2006 1:34 PM
To: tesla@xxxxxxxxxx
Subject: bulkheads / baffles in secondaries

Original poster: Gomez Addams <gomezaddams@xxxxxxxxx>

This is addressed to those who have experience installing internal
baffles or bulkheads in secondaries, for the purpose of preventing
internal creepage sparks (internal racing arcs):

I have never used internal baffles before, and have never seemed to
need them on any of the secondaries I've built.  (although once,
someone building secondaries for me for commercial sale at a company
I was consulting for had racing arc problems, but I soon discovered
they had decided to paint the secondary form with black paint "for
looks" before winding it!)

But now I am attempting to build one of the most robust, good-
looking, and efficient / high-performing coils I've ever built,
taking into account all the new developments which have turned up
since I last built a coil, so I thought I'd go ahead and install
baffles just for the heck of it.  I seriously doubt they'll do any
harm, and if they'll make the secondary even more "mistake-resistant"
then I'm all for it.

So my main question is: do you typically install them while building
the form, with holes in the center of each baffle for your winder
shaft (assuming you use one), or do you wind the coil first, remove
the end plates, install solid baffles, and replace the end plates, or
what?

Since I have a large enough lathe, I _could_ wind the form without a
shaft going all the way through, but I prefer to use a shaft to
provide support to the form.

Also, I'm thinking it would be smart to leave holes for ventilation
so things like glue fumes (after construction) and later, ozone, can
escape the interior, so perhaps baffles with center openings are best?

Opinions?

  - Bill Lemieux