[AT] A long shot--Wisconsin part Brazing and cast iron

[Larry D. Goss]

"I've heard older guys talking about using ordinary borax as flux"

LOL!  I guess I know where that puts me.  :-)  "Back in the day" when I
was learning all this stuff, borax was the chemical equivalent of "the"
flux that was available -- but that was over 50 years ago.

Larry

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Mike Reggie
Sent: Friday, June 30, 2006 3:27 AM
To: at at lists.antique-tractor.com
Subject: Re: [AT] A long shot--Wisconsin part Brazing and cast iron



  Sure John, The method I use after I've sanded and cleaned the parts is
to 
apply the flux,I prefer the paste type, usually with an acid swab to all
the 
areas that will be brazed, the same way you would apply soldering paste
to 
copper plumbing pipes you are about to sweat.  I always have a tub of 
brazing flux on hand,[I always get the white flux so it can also be used
for 
silver slodering as well] and it doesn't matter if sits around and gets
old 
and dries up, all you have to do is add water and mix it up, I actually
tend 
to over-thin it so it spreads well and is easier to get in all the joint

areas.
I always pre flux the parts weather I'm using the flux covered rods or
the 
bare ones, the only difference being that as I'm flowing the rod into
the 
joint, I'd be periodically dipping the bare rod into the flux. I guess
the 
powdered flux is ok too, just not as easy to use. I've heard older guys 
talking about using ordinary borax as flux, but I've always had good
success 
with the way I do it so I  stick with it, and that is the method I use
no 
matter what the materials are, stainless, brass, cast iron, steel,
copper, 
etc. In fact, this very afternoon I had to  machine out and counterbore
a 
cast iron pump endbell, turn and fit a stainless steel sleeve and braze
it 
in, and I did it as I describe above  with very satisfactory results.

  Again, try to keep in mind that what is happening in the joint is 
dependent upon capillary action more akin to sweating plumbing pipes, 
nothing like gas welding muffler pipes.

I hope this helps ....... Mike





----Original Message Follows----
From: John Wilkens <jwilkens at eoni.com>
Reply-To: Antique tractor email discussion group 
<at at lists.antique-tractor.com>
To: Antique tractor email discussion group
<at at lists.antique-tractor.com>
Subject: Re: [AT] A long shot--Wisconsin part
Date: Thu, 29 Jun 2006 08:30:05 -0700

Thanks for the information Mike.  Hope you won't mind one more
question..... 
   I've only just used the flux-covered brazing rod.  What method would
you 
use to use "plenty of good flux?"  How and when do you apply it?  Is it
the 
usual powered flux that you would dip your hot brass rod in?    John




At 11:52 PM 06/28/2006, you wrote:

>  John:  I might be able to offer some information on the rubbing of
the 
>carbon stick on the weld.
>
>If you've ever had a nice fresh cast iron weld crack on you, you will
have 
>noticed that it doesn't crack on the weld itself, it cracks on either
side 
>of the weld.  without getting into all the science as to why that 
>happens,[I've tried for years to understand it] it is basically because
the 
>heat of the weld draws the carbon from the surrounding part of the
metal to 
>the heat zone of the weld, and causes it to crack. So the theory was
that 
>the carbon would help to fill in at the spots it was being pulled from,

>this is also the reason for the pre and post heating, and burying in
sand 
>or lime, etc.
>
>  I do all kinds of welding on an almost daily basis, and a part of
that is 
>sometimes cast iron, some of it with stick, and some of it with
heli-arc, I 
>dislike it very much, there have been really great products developed
in 
>the last 20 or so years for cast iron welding, but its whole purpose is
for
>repair, I have never seen it as a means of normal cast iron joinery. No

>mater how much I've done, or what I see others far more talented and 
>informed than myself do, I just can't seem to get comfortable with the 
>whole idea of cast iron welding.
>
>That being said, my preferred method for the repair of cast iron is 
>brazing, be it with brass, silver, or with cast iron filler, it just
seems 
>to "work" better. Just remember, clean, clean, clean, and plenty of
quality 
>flux, and of course never forget that brazing is dependent on capillary

>action, it is not a soft weld.
>
>  This is just my opinion, I hope it is of some help   ........ Mike
>
>





                    In the wide-open spaces of NE Oregon



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