Dave,
I use 308 rod on 304 and 321 stainless. They make a 347 rod for 321 but 308
can be used. It is very important to clean the material and remove any burrs
or machine marks as they will allow contaminates to be trapped in the weld.
Some of the high tech coolants used in CNC machines today cause a lot of
problems as they are a bitch to get off. Just heard of a problem with
replacement hips contaminated with coolant that sterlizing didn't remove the
stuff.
Match the tungsen size with the metal thickness. Sharpen the tungsen to a long
point and get some BIG glasses...better you than me...I've got three different
pair of glasses to see with now!!! Straight Argon is fine.
Hope this helps!
joe
Dave Dahlgren wrote:
> Joe what do you use to weld 304 and 321 stainless?? what rod
> and what gas to get that Oh so fine bead?? it is for a set
> of stainless headers for a friends 'vintage ' indy car..
> Dave Dahlgren
>
> Joe Timney wrote:
> >
> > Gas Shielding:
> >
> > This is not easy to explain...bear with me!
> >
> > The reason you do not want to use argon with a mig gun is called "low
> > ionization or cold shutting". Argon allows that the gap between the end
> > of the wire and the work be very small when the arc jumps. This causes a
> > small crack at the toe of the weld. The weld will look very good but it
> > can fracture. Using a 80/20, Co2 / Argon mix will cause a high ionzation
> > ( a bigger gap) and allow the metal to come to temperature before the
> > filler metal hits the area. Straight Co2 will typically have more
> > splatter around the weld as compared to a 80/20 mix.
> >
> > Stick Welding:
> >
> > If you burn thru, which is easy welding .125 wall tubing, the metal on
> > the inside of the tube is now brittle because it is not shielded by the
> > flux on the rod. This CAN cause a weld fracture. This is why NHRA has
> > banned the use of stick welding on all race cars.
> >
> > Mig Welding:
> >
> > Nascar uses mig welding over Tig probably because of the miles of tubing
> > in one of those cars. Teams in the know, are now TIG welding the
> > chassis.
> >
> > We all have had experience welding up cars/bikes that have held up thru
> > crashes and years of abuse using mig, gas, arc and tig. Dollar for
> > dollar, I spend the time to tig all tubing as from education in
> > metalugy, I have concluded that it is the best welding process for thin
> > tubing. I have a book from a gas supplier outlining the proper uses of
> > shielding gas and am willing to try to scan some approprate pages in to
> > my computor if someone would like to see them.
> >
> > I'm not a teacher so I hope I have explained this so everyone can
> > understand it!?!
> >
> > joe
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