[Farmall] O-12 chores

[John Hall]

I've seen two different guys weld cast with something besides nickel rod. 
One welded dad's 10-20 manifold with a mig gun years ago. This was before I 
ever started getting an education on cast. Anyway, it is still holding.
I used to work with a guy who Tig welded heads for a machine shop and 
guaranteed his work.

Most guys do as you say by preheating the parts and then slowly cooling 
them. One friend used tohave a cookstove in his shop for controlled cooling 
and heating. When I welded up the fuel pump on my Titan I heated it real hot 
and kept it that way. Careful you don't get too hot and get a blow out when 
welding--especially if you hit an air pocket. When done I  buried it in a 
bucket of sand to provide slow cooling.

Of course you need to start welding some non-critical parts first. Then you 
get to experience first hand what happens when you missed drilling out all 
of a crack---10 seconds with the rosebud and then.....well, lets just say 
cast iron can take you to school, and might send you home crying.

There have been some good threads on cast welding on either the AT or SEL 
list---may have been on both. Some pretty knowledgable folks there.

By the way, McMaster-Carr is a good place to get odd and end pieces of matl. 
for machining.

John
----- Original Message ----- 
From: <olmstead at ridgenet.net>
To: "Farmall/IHC mailing list" <farmall at lists.antique-tractor.com>
Sent: Tuesday, December 26, 2006 2:45 PM
Subject: Re: [Farmall] O-12 chores


>I agree that I have little to lose, John.  And welding cast iron is
> certainly a talent that I would like to have.
>
> What scares me is the guys who say "I've welded lots of cast iron, just
> zapped it with the MIG, and it worked fine".  That goes against everything
> I've ever read about what happens in the iron adjacent to the weld, which
> gets very hot and then chilled by the base metal.  It winds up being very
> brittle and under a lot of stress.  In order to do a lasting job on cast
> iron, the whole part needs to be virtually red hot while you are welding,
> and then cooled very slowly.
>
> Then there's the problem with porosity, contaminated metal, warpage,
> cracking and so on.  Doing it right is not a simple matter.  I figured
> that I might be able to learn to braze a lot quicker than to weld.
>
> Brazing and soldering are also magical techniques.  In order to do what
> the experts do, you need to control the temperature of the pool so closely
> that you can keep it in the 'mushy' stage, where it doesn't liquefy and
> run right off the work.  I've never been good at that.
>
> Gotta obtain some 2" round stock before I can start making crank
> supports....  none in my scrap pile.
>
> -Karl