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Re: [TCML] Joining two 25 foot rolls of copper tubing

I have spliced 1/4" copper tubing several times with very nice results and they have been barely noticeable, after cleaning up with fine sand paper. I took a solid piece of copper wire at least 2" long, I can't remember the gauge, that would just slide into the tubing. I tried it before this with a much shorter piece of wire but I found it much more difficult to get a smooth bend with the short piece of wire in the splice than with the longer piece. Actually, the longer the wire, the easier I found it to bend, up to a point. I also rounded the ends of the piece of copper wire, so when I bent the tubing at the joint, the sharp ends of the wire wouldn't try to bend through or create a bump on the outside of the tubing. Once I created a tight fitting joint, I took a propane torch and sweat soldered the joint, just like a copper pipe fitting. With the long piece of wire inside, the tubing joint was just a little bit harder to bend than the rest of it was.
Do NOT sweat in too much solder or it will make the joint difficult to bend. Just sweat in enough to assure the wire is attached to the tubing at the joint. I learned this the hard way. I also practiced this on several short pieces of tubing until I learned this technique. That is how I discovered it is better to use a longer piece of wire inside the tubing and to smooth the ends. I hope this helps. 
Paul
Think Positive
----- Original Message ----- From: "dave pierson" <dave_p@xxxxxxxxxxx> 
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Thursday, May 20, 2010 8:44 AM
Subject: Re: [TCML] Joining two 25 foot rolls of copper tubing





New dwp:     dave_p@xxxxxxxxxxx


I have two 25 foot rolls of 1/4 copper tubing. I could not see how it
might be possible to join the two rolls to make a spiral primary. So
I ordered a 50 foot roll. But I'm curious if anyone has joined two
such rolls?

   I haven't, however have done analagous things in plumbing,
   in the old solder copper pipes days, albeit with larger
   tubing.  Generally 1/4" dia tubing is joined with 'compression
   fittings', not real applicable here.

   Larger bore plumbing uses 'sweat soldering' of purpose
   designed couplings.  If of interest, will describe,
   tho hopefully better description on the web somewhere?
   trick would be to find 'coupling fitting', likely have
   to fake one with slightly larger tubing.  Some ways
   simpler than plumbing work: no need to be water tight.

   Another approach would be to sweat solder a solid 'pin',
   snug fit to the bore of the tube, mebbe an inch long?

   a third would be to file/etc mating 'dovetail' joints,
   then try to 'butt solder'.  weakish.

   ANY of these will leave a mild bulge, tho last two not
   so much: I'd not expect problems, tho, if turns are close..

   ANY would want care in filing/sanding afterwards, to smooth
   out potential Corona Points.

   ANY would create more or less stiff/hard spot: bending to
   form winding would want care.

   If any better suggestions offered, so much the better.

   best
    dwp
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