[BC] Silver soldering BRASS

[RichardBJohnson at comcast.net]

Just use a decent flux and don't get the joint hot enough to melt
either the copper or the brass.

http://www.silvaloy.com/fluxes.php

I have watched Jampro Antenna fabricators braze the
brass elbows to the copper pipe of antenna fittings using
nothing but skill and the usual cheap flux one uses with
brazing rod!

Silvaloy is brazing rod with some silver, which lowers its
melting temperature somewhat, making it even easier to use.
What is often forgotten is that metals like copper and brass
are highly conductive of heat and have a high "specific heat,"
meaning that they take a lot of energy to raise their temperature.
When using an oxyacetylene torch, you need to use a broad
flame and slowly raise the work's temperature. You don't hit
the work with a pencil, you will just poke holes in it.

If you've never brazed anything before, your first on-site
job is not the time to learn. Ask some expert at a
welding shop (not a muffler shop, BTW) to show you
how to get it right. Then experiment at home.

When I worked for RCA Service Company, we went
to "school" to learn how to install field flanges on
TV antennas. They were silver-soldered brass
onto copper pipe. During the courses, I screwed
up many flanges to where they couldn't even be
repaired! However, in the field, they were all perfect.
It's a learned skill --not automatic.

--
Cheers,
Richard B. Johnson
Read about my book
http://www.LymanSchool.org


 -------------- Original message ----------------------
From: Mike McCarthy <Towers at mre.com>
> If there is a way to oxy/acet solder silvaloy to brass, someone please show 
> me.  Every time I've tried it, it won't flow and the brass distorts and/or 
> melts. It's like the brass is dissimilar enough to the flux that it won't 
> flow. But Kintornics seems to make it work using 45% silver....which 
> requires even more heat.  So I don't get it....and haven't had the time to 
> play with it as I'm usually under the gun to get something done.  So I 
> improvise using threaded plumbing fittings which I can solder.
> 
> MM
> 
> At 02:26 PM 10/16/2007 +0000, RichardBJohnson at comcast.net wrote
> 
> >In the olden days, when broadcasters kept their antennas and
> >ground-systems in shape, I remember seeing several pages
> >of information about copper straps, ground-screens, and
> >radials. I think it's in the NAB Engineering Handbook if
> >you can find an old copy. Anyway, the 'tee' connection was
> >handled with 4 holes punched into the straps with 1/4-20
> >brass bolts and nuts. The result was then flowed over
> >with silver solder. The "ell" connection was done with
> >a fold (the corners of the rectangle that was supposed to
> >connect the edges of the ground-screen, both at the
> >tower base and at the end of the screen. The edges of
> >the ground-screen were compressed between two
> >straps, held at about 18 inch intervals with 1/4-20 brass
> >bolts, then silver-soldered as well. The radials were
> >installed first and ran under the ground screen to the
> >strap that ran around the tower base.
> >
> >--
> >Cheers,
> >Richard B. Johnson
> >Read about my book
> >http://www.LymanSchool.org
> 
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