RE: [TowerTalk] Site Grounding

[Jim Lux <jimlux@earthlink.net>]

At 12:55 PM 10/21/2003 -0400, Tony King - W4ZT wrote:
> At 12:38 PM 10/21/2003, Jim Lux wrote:
> <snip>
> > By the way, I'm not sure what you really want here is a brazed 
> > copper/copper joint.  Brazing is usually used to refer to a joint using 
> > brass or copper to join, e.g. steel, making use of the fact that the 
> > melting point of the brazing metal is lower than that of the materials 
> > being joined (otherwise it would be called "welding", no?)
>
> You're absolutely right Jim. Many times it's called braze welding. 
> Unfortunately when you tell someone they will "weld" something they're not 
> going to look any farther because they think of sparks, arcs and something 
> they can't do. Fortunately you can braze even copper to copper with simple 
> materials available at the local Home Depot.


Indeed... the little inexpensive Mapp/Oxy torch set for about $50 works 
quite nicely, and even comes with flux coated rods.  Everyone should try it 
at least once.  Brazing makes a nice way to repair stuff that breaks and 
just needs to be reattached, but doesn't need phenomenal strength.  It's 
about as hard as soldering (actually, perhaps, even easier... A nice hot 
torch makes life much easier!)

I haven't tried brazing (in the brass/copper filler metal sense) copper to 
copper.  Silver solder always worked well enough for my needs, and the MP 
of silver solder is much lower than that of copper, so I didn't have to 
worry about melting the workpiece.

I've also heard that one can braze/silver solder aluminum, if you're 
careful. The problem is that aluminum melts at about 700 degrees, and it's 
not even red at that temperature, so it's hard to tell if you're 
overheating the joint until it's too late and you've got a puddle of molten 
aluminum.


> > Using brass or copper to join copper would require getting the bond metal 
> > almost as hot as the MP of the metal being joined.  Why not just use 
> > thermite (exothermic welding) and make it a real copper/copper/copper 
> > bond, in that case?
>
> And that's an excellent choice if it's available :)

Call up the local "electrical supply" place and they'll probably have it. 
It's required for all manner of ground connections.  One can probably also 
mail order it, although they might stick you with the $5 Hazmat shipping fee.


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