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Re: [TCML] Coil V1.8

Having done a number of sonotube coils, there are just a few tips i have to

1) remove the outside layer of paper.  this can sometimes simply be peeled
back, but often it wants to shred itself.  I found that using some cheap
packing tape, firmly sticking it to the outside, then peeling that off,
removed the black pigment as needed.  You go through a lot of tape, but who
cares, its cheap.

2) make sure the tube is kept dry, i like to leave it out in the sun on a
hot summer day if possible to help drive the surface moisture out.

3) despite what Dr R says, i have never removed the inner wrapping of paper
from the tube.  To me it appears to be a wax coating, which seems like a
*good* thing for maintaining the integrity of the tube.  If you do decide to
remove it, surely coat it with some varnish.

4) i coat the tube with thin (as in, new) oil-based polyurethane.  After 1-2
coats, i fine sand the surface, then go for one last coat before winding the
coil.  Let this set up for a day or more if you can, you'd like to be sure
its pretty dry before trapping it in the winding, though i dont think it
hurts if its not.  Ive unwound coils that were many years old to find the
varnish was still liquid inside.

5) i like to epoxy coat the winding using envirotex lite, but before that i
clean the winding with rubbing alcohol and then give it 1 thin coat of
varnish.  The epoxy doesnt really wick into the winding that well, its more
of an exterior protection.  The varnish WILL wick into the winding and serve
to hold it together.

As of yet, all of my sonotube coils are quite successful, from 8" to 12.75"
diameter, all capable of sparks of 3X the coil length.  The 8" coil gets
used for our shows, which means its got a lot of run time on it with 10 foot
sparks (its a 45" winding).  The coils are somewhat fragile, but i think the
force required to dent the sonotube is more abuse than you should ever
subject your coils to.  My 8" coil fell to the pavement one time and really
screwed it up bad.  I cleaned it up, then decided to do an epoxy/fiberglass
coating over the whole thing, now its very tough, but you cant see the
pretty wire anymore (who cares, the sparks are great).


On Thu, Aug 5, 2010 at 10:36 PM, DC Cox <resonance@xxxxxxxxxxxx> wrote:

> yes, 2-3 coats of Dolph's AC-43 which soaks into the tube and strengthens
> it
> considerable. It stiffens it up.
> I usually do 3 inches on each end with G.E. Glyptal (local elec. motor
> rewind shop), 2 coats, to give the ends a nice red color as the AC-43 does
> not look very attractive on the cardboard tube.  Your wire is wound over
> the
> AC-43.
> Remove the inner spiral which contains the water release agent.  Sand tuber
> thoroughly inside and out.  Be sure you get all the lettering and printing
> off the outside of the tube.
> Dr. Resonance
> On Thu, Aug 5, 2010 at 10:06 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx>
> wrote:
> > Hi Bart
> >
> > Indeed I had to raise the secondary. Even my new one. No flashover or
> > racing sparks!  Thanks for the accurate calculations.
> >
> > On to the next challenge. I just got some universal motors I'm going to
> try
> > in asrgs.
> >
> > Also I got some 8" sonotube.  Problem with sonotube is it seems flimsy
> and
> > too easily dentable. Anybody got suggestions for strengthening sonotube
>  for
> > use as a secondary winding core??
> >
> > Cheers
> >
> > Joe
> >
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