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RE: bulkheads / baffles in secondaries

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

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Saturday, August 19, 2006 6:09 PM
To: tesla@xxxxxxxxxx
Subject: Re: bulkheads / baffles in secondaries

Original poster: Gomez Addams <gomezaddams@xxxxxxxxx>

On Aug 15, 2006, at 5:35 PM, Tesla list wrote:

>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

> How thick?  Do you mean a drinking cup?  A pipe cap?  Or?

I'd be guessing but an end cap is about as thick as a dime.

Plastic cup used for drinking. Really thin.

Mine are made from 1/2" (0.5") thick UV-inhibited PVC.

>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,

> Did you use conventional acetic acid -based silicone caulk?  It's not so
great for high voltage use.

I've never seen any non-acetic acid based silicone seal.

>I've been thinking about using one of the 2-part silicone rubber

Hmm, never seen that before. Perhaps it is not yet available where I live.
I've been on the watch for some sort of non-acetic acid based seal. I've
been suspicious that the acetic acid vapor might include gaseous water and
water sure is something I would not want in a secondary tube particularly
when PVC seems to attract moisture. I forget the word for substances that
absorb moisture from the air.

>Holes left unsealed in the baffles would defeat the purpose of the

> I thought the purpose was to greatly increase tracking distance.  In
any case, I turned the baffles without holes.  :)

Excellent! Yea, it is to block the path.

The top and bottom bulkheads will get holes for securing to the base
and for securing the toroid.

>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.

> I don't like the fragility of most epoxies, although I could probably
Find one that is tough and not brittle, if I looked hard enough.  Master
Bond makes an epoxy for everything.

Never heard of master bond.

Yeah, I've had difficulties with brittleness. For baffles, if the tube is
inflexible it won't be an issue, but I've poured epoxy into end caps to seal
and stabilize the end bolts only to have it crack, come out, or the bolt
fall off.

>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.

Tight fitting is definitely not a problem with the baffles I just

>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
>over and seal the holes after winding.

> I've decided to turn the form between centers, no shaft.  I think the
Coil form will be plenty strong.

Yep, the advantage of no continuous shaft is that you can just adjust the
winder for the length of the tube. I usually attached end-caps to the
winder, plugged the end caps into the tube and it was enough to get it
wound. Then I secure the winding at both ends and put other caps on and test
for burn outs before coating and completion.

Folks have found that PVC pipe sold in the US, have floor sweepings inside,
it's quite impure. Terry found Bug parts, whole bugs, hair, metal shavings,
screws and other things one would find in a typical shop after sweeping up.

It seems they just sweep it all into the molten plastic.

  - B(G)L