Re: tesla coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "davep by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<davep-at-quik-dot-com>
> 
> Tesla list wrote:
> 
> > Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <ANTarchimedes-at-aol-dot-com>
> 
> > I'm having a bit of a problem.  When winding the secondary, how do I
keep the
> > coil from kinking? Or from accidently overlapping itself. it's not much
of a
> > technical question, but I know it will affect my coil's output.  How do I
> > keep the loops from sliding over themselves, and how to I keep the
secondary
> > taut when I'm not holding it?
> 
>         IIR, we rigged a clampig drag opn the supply reel.  Nothing
>         elaborate, just a bolt and a wing nut thru the supply reel, so
>         it did not spin freely.  That and care in winding.  (We were
>         working with the secondary in a jig (actually: a metal cutting
>         lathe, with the power off.)  I can't picture tyring to freehand
>         a seconday....
> 
>         best
>         dwp

	I have always had good luck in tensioning the wire by hand (or really
finger) as it went onto the secondary; that way you can also make sure
the turns are tight and do not overlap.  The biggest coil I have wound
this way was a 5.25" dia by 18" long secondary, using #28 wire.  Took a
couple of hours to wind it with the winder being turned by an electric
drill slowed with a variac.  Wire is fed OVER the end of the spool,
after first making sure the end is smooth.  That way there is almost
none of the inertia which would be seen if the spool rotated, and you
can stop and think if you run into trouble.  Always keep a bunch of
pieces of pre-cut masking tape to hold things down while thinking.

	The winder I use is a 36" piece of 3/8" threaded steel rod, running in
brass bushings at each end.  (The rod is turned down to pass through the
bushings, which are held in place with wing nuts for easy removal.) 
Wooden cones are turned to fit the ends of the form, and only a couple
of different sizes will suffice for small coils.  Nuts and washers are
placed on the rod to force the cones into the form, and then locked with
an additional nut at each end.  Normally use a hand crank, but the crank
is attached to the end of the rod, which is turned down to 1/4" diameter
to fit common "radio knobs".. The knob can be removed and an electric
drill attached if powered drive is desired.  I've would a number of 3.1"
OD, 16" long coils (a bit over 1000 turns of #30 wire, of which I have a
large supply).  With hand cranking it takes about an hour to fill the
form.  

	I have also wound a couple of these same forms by simply holding onto
the secondary from and turning it in my hands, with fingers again
applying tension to the wire.  That takes about two or three times as
long, but if the start of the winding is made nice and square with the
form, results in a very nice looking coil.  Same precaution about
pre-cut masking tape.  I would think this method would work pretty well
for large forms provided the wire isn't so large that it can't be held
tight enough to get a smooth and tight coil.

	Of course, for the big jobs most of you guys seem to be building,
something more heroic is reuired!

Ed 

P.S. Don't recommend using a powered lathe, as you can't stop the chuck
fast enough when something goes wrong, as it always will.  Turning the
chuck by hand is about equivalent to what I do; my coils are small and I
thought the simple winder was the easiest way to go since my lathe.
although 11" swing, only has 30" span between centers.