Re: Fiat PVC, Fiat Lux
> Original Poster: Yuri Markov <wmondale-at-hotmail-dot-com>
> I finally got a nice clean 4-inch wide PVC pipe, and 22 gauge magnet wire
> wind. This new secondary will replace my insult to the hobby of Tesla
> coiling, my 2-inch cardboard wrapping paper tube, 30-gauge wire seconday.
> This time I'm going to get it right. Everything. But first I need to know
> what everything is. So far I've sanded the pipe down to a fairly smooth,
> at all shiney surface. Should I continue sanding with fine paper until it
> really quite smooth? As smooth as it was before?
Doesn't make much difference...The smoothness of the form doesn't have much
effect on the performance.
Next, I know that I have to
> coat the pipe with something before winding. What is this magical
> that I should use?
Polyurethane varnish is popular.. It is tough and slightly resilient. If
you time it right, it will still be tacky when you wind, so that it holds
the windings in place if you drop tension as you wind. A solvent dipped rag
will also do the same thing, but pick a solvent that softens the varnish,
but not the insulation on the wire.
ANother choice is Glyptal, which is tacky for a long time, and also quite
temperature resistant, and solvent resistant, and is what they use in
motors and the like.
Of course, I just used spray acrylic, and it worked just fine...
Will it go on nice and evenly, or will I have to re-sand
If you set up a jig to hold your tube and roll it slowly (say, 10-60 rpm,
ish) (very handy for the winding process) then you can just slather the
stuff on and leave the tube rolling as it dries.
> Next, I assume I wind the wire. (Yawn... I wish I had a lathe...)
A lathe doesn't always make it easy. I wound a 4"x24" secondary last year
with a lathe, and it was quite a coordination challenge to hold the wire
tension, move the traverse, and engage the lathe clutch. Even harder was
stopping. I am convinced now that the ideal is a small gearmotor with a
foot switch. You can "pulse width modulate" the gear motor using your foot
to speed and slow as required. Actually, the next one I wind (I just
acquired a piece of 10" PVC 5 feet long) I think I will use a sort of belt
drive with a 400 RPM motor (a rubber belt around the pvc and around the
motor shaft, which should give me a 10:1 reduction. 40 RPM seems a nice
rate at which to wind fairly stiff wire.
> Then am I meant to put another coat of the magical coil coating on top of
yep.. slather or spray on another coat..
Sand? Does it matter if it's nice and shiny in the end? How do I make
> sure I don't sand the enamel off the wire?
Extreme care, knowing that if you screw up, it is irrevocable and very
tedious to fix.
Please help. Also, I am vaguely
> aware that I should make the coil airtight with a plastic disk on each
> Why is this necessary?
So the 10 foot arcs that your coil will make (we can hope!!) don't take the
short way through the middle of the form.
>What are the advantages of an airtight coil form?
Actually, you do want a few small holes to let the thing breathe.
> And, last of all, can I attach these disks using hot glue, or is that a
Attach anyway you feel comfortable. I am a real fan of silicone sealant.
You can push it around with your finger and it makes a nice seal, and can
actually be removed with a razor blade or x-acto (tm) knife.
I apologize if I've asked too many questions in one post. Answers to
> some, or preferably all of these questions would be appreciated and
> eternally helpful. Thank you.
> -Yuri Markov
> Proud owner of a PVC pipe
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