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Re: Winding primaries

Hi Dereck,

A very common and important question you ask...

	Winding primaries takes some practice but here are my tips...

I made a really nice primary with 1/4 inch copper refrigeration tubing from
the hardware store.  It is a big thing and has about 20 turns spaced only
1/4 inch apart.  See the pictures at:

http://www.peakpeak-dot-com/~terryf/tesla/experiments/modact/modact.html

I have to make a new one soon too...

Most people really like the 1/4 inch tubing for primaries.  For low to
medium power (0-2000 watt) coils it is just right.  It comes in very nice
packages and is easily manipulated.  I use 1/4 inch fuse holder clamps to
connect to it with a simple snap on assembly too.

This is how I built the big primary.

First I got a large two foot diameter 1 inch thick round pine base form the
hardware store.  It was meant to be used as a do-it-yourself table top.
Any strong base would work but be sure it is STRONG.  

Next, I cut a bunch of support rails out of wood (I live in dry Colorado,
you may want to use plastic in non desert regions).  I had enough supports
so that the soft tubing would be supported every 6 inches.  The supports
were slotted wood with 1/4 inch slots cut with a table saw as one piece of
wood and then the rails were sliced out of that single chunk.  So I had a
bunch of rails with 1/4 inch slots, 1/4 inch deep, and 1/4 inch apart.  I
then drilled a hole under each slot because I knew I was going to lash the
tubing down with nylon cord.

I glued the rails to the large round table top being very sure to space the
rails out a bit as I went around the circle so the tubing would lay as a
spiral.  Lots of rulers and measuring here.

I then took the brand new tubing, which comes as a nice coil, out of the
box without disturbing the tubing much (cut the box away).  Starting at the
center and working outward I just laid the tubing on the base and expanded
the coil carefully and evenly until it would just drop into the slots.  I
was very careful to do minimal bending and basically just unwound the
tubing a little so it would expand as large chunks at a time.

The tubing fell into place without kinks or other problems and I tied it
down as I went.  There is 100 feet of tubing on mine, so I spliced it with
a 1.5 inch piece of brass tubing from the hobby store with a torch and
solder.  However, you can get the tubing in 100 foot lengths as a found out
later.

I have used this primary for two years and it is very durable and has a
very large tuning range.  As the seasons pass the wood expands and
contracts which broke some boards I had glued to the bottom across the
grain of the wood for supports but the coil itself is holding up perfectly.
 The tubing is tarnishing a little but nowhere near what my friends in
humid regions see with coils turning green and all.

I definitely recommend "going all out" and doing it right the first time to
make something that will last a long time.  Most of my older primaries were
thrown out due to poor construction rather than being the wrong design.

Hope this gives you some ideas for yours...  I am sure others have more
tips too.

Cheers,

	Terry


At 09:09 PM 12/19/1999 -0600, you wrote:
>Hi,
>
>This is going to sound like a dumb question, nevertheless: can someone give 
>me pointers on winding primaries, such as the flat Archimedes spiral or 
>suacer/bowl shapes? I have built a small TC a few days ago, my first, with a 
>flat spiral primary made of 10AWG bare copper wire. It doesn't make huge 
>sparks, but there's something about seeing your first coil work that feels 
>great. Anyways, the primary was a pain in the nether regions to make. If 
>anyone has any winding methods that they find make it go easier, let me 
>know. Thanks in advance!
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