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

[John Wilkens]

Helps a lot Mike!  Good, detailed interesting information which will 
help me.  I'll make a copy of your email for future 
reference......since I find myself forgetting a little 
lately!  Thanks.    John W.



At 01:26 AM 06/30/2006, you wrote:


>  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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>
>
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                    In the wide-open spaces of NE Oregon