Re: status report etc.

In a message dated 95-08-30 22:40:46 EDT, tesla-at-grendel.objinc-dot-com writes:

>I finally have a few minutes to do more than scrutinize and redistribute 
>the tesla mail!  
>I was reading about the variable inductance ideas and thought that magnetite
>may make a suitable core material.  I believe that ferrite is some form of
>magnetite (Fe3O4).  The next question is where to get it? That I don't know.
>Perhaps some chemical supply houses or some geological/mineral supply
>Any way, my tesla coil is coming along well.  I have the secondary virtually
>done except for mounting the toroid.  The primary forms are done and half of

>the primary is wound.  It turns out that I'll need well over 50' for this 
>thing.  That means that I will indeed have to do some creative soldering
>to smoothly butt-join the two 50' pieces of 3/8" tubing.


I had to do the same thing.  I bought 2 boxes of tubing (50' ea) and I
believe the first box ran out at about 9 or 10 turns.  Then I used a small
piece of 1/4" copper tubing slightly flattened out to make it wider and
slipped the ends of the 3/8" tubing over it to keep each end aligned and then
soldered it with a torch and wiped the excess solder off.  It turned out very
well, you can hardly see it. 
>The details of the secondary are:
>4"x20" winding of 24ga wire.  950 turns.  I initially coated the wire with
>PU (minwax urethane).  However, that wasn't going on well/thick enough 
>for me, so I got this stuff called "Build 50" by Behr.  It is an epoxy 
>that is used to make thick one coat finishes on things.  I put the wound 
>secondary on the lathe (or winding device) and turned it at about 20 rpm.
>Then I slathered the stuff on and let it turn for about 4 hours.  This stuff
>worked quite well.  I have a thick insulating (I hope :-)) layer that is 
>as hard as epoxy gets.  I also put solid end caps on the pvc pipe so that
>the interior is entirely sealed.   Unfortunately I missed the reason 
>for using epoxy and used PVC cement to seal it.  (I read the reason after
>it was too late). (The reason is exploding fumes in the secondary form)
>I used Ed Sonderman's great idea for the toroid attachment and glued a 
>pvc pipe cap to the top end of the secondary.

The secondary sounds good.  
>The details of the primary winding are:
>30degree banked spiral of 3/8" copper tubing separated by 3/8".  16 turns.
>I used plywood for the base and triangular forms.  On the plywood triangles
>I put some plexiglass "combs" that hold the tubing.  I used a drill press
>set up a jig to allow me to use a 3/8" milling cutter to drill C shaped
>in the edge of the plexiglass.  The notches are ever so slightly more than 
>half so that the tubing snaps into place.  The combs are held in place by
>nylon screws that slide in slots in the triangles.  The reason for the 
>slots is so that I can have a little slop and so that the tubing can
>spiral out rather than having to make jumps between circular tracks.

Your primary sounds a lot like mine.  It should look great when you get it

Ed Sonderman
>I have some pictures that I'll send when I get them scanned in.
>More later...