Cast iron welding, what do you do.

[Propane1]

To weld cast iron. I have a a/c stick welder. Just for fun, my son and I had a exhaust manifold to weld up a crack/hole, with the stick welder. You tube has lots of videos on successfull repairs. So we tryed. We are not trained welders. We tryed 7014, 6013, a cast rod, don’t know number and a idiot rod as they are called around here, blue flux. All didn’t work. They just burned away the cast and the rod did not stick at all. Can you change the polarity and weld that way with an a/c welder only. And if I could have, would the rods I used stuck to the cast iron ?

Then tryed a mig welder. That didn’t work. So I know that I can weld it with torch’s and bronze rod. So was not worried. Put a piece of rod on the hole for filler and bronzed it. Not pretty but stops the leak.

Noel

 

[olcowhand]

You need nickel or stainless rods for cast, and must cool slowly or it will crack. Brazing works great, but once brazed you can't stick weld unless you grind away ALL the brazing.

 

[dodge trucker]

I thought that you had to heat up the whole casting before welding, and post heat afterwards and yeah, nickel rod, I forgot what polarity I thought that it was DC -

 

[Toomanytoys84]

I never tried it. But I had a guy weld the ear back on a cub cadet gear reduction box. He welded it, grinded it and if not for the shiny spot you would of never been able to tell.

He since has passed away.

 

[jabelman]

I have done it with mig before, the first time I drilled holes and used nails as dowel pins. just used lowest heat setting and it worked fine.
2nd time I just tacked it slowly on low heat, it made scary sounds but it stucj

 

[olcowhand]

I thought that you had to heat up the whole casting before welding, and post heat afterwards and yeah, nickel rod, I forgot what polarity I thought that it was DC -

Yes, left the preheat thing out...brain fart. I never remember polarity and don't have to, as my welder has a chart on it for DC polarity usage.

 

[secondtry]

One of the problems with cast iron is if you grind it to clean it up for welding the heat of grinding releases the carbon and the grinding wheel smears that carbon across the weld area so when you try to weld it you are trying to weld through the layer of carbon and that is near impossible. Even a carbide bur can produce enough heat to smear the carbon. I have welded a pillow block bearing housing with a cast rod, DC electrode +. You can't change the polarity of an AC output welder. I have never attempted to weld cast with AC and I believe the rod I used was marked DC +. Don

 

[ol' stonebreaker]

Secondtry, how do you change polarity on an A/C welder?
Mike

 

[Cvans]

Secondtry, how do you change polarity on an A/C welder?

If you have a welder with plug in cables you can do it. Normally the polarity is not changed when using AC.
I've had the best luck with Nickel rod and brazing. If the right procedure is used cracking shouldn't be a problem with those two rods.

 

[ol' stonebreaker]

IMO the polarity is changing 60 times per second.
Mike

 

[secondtry]

Secondtry, how do you change polarity on an A/C welder?
Mike

You don"t Went back and proof read my previous post and edited Thanks for the heads up. Don

 

[ol' stonebreaker]

I don't usually look for debate but when I see wrong facts I'll call it. I'm not always right but I strive to be based on knowledge.
Mike

 

[dodge trucker]

You don't change polarity on AC the power company does that for you 60x a second

Like asking the parts guys for a muffler bearing you'd keep someone busy for a while

 

[Toomanytoys84]

Unless you are in some parts of Europe and its 50Hz.

 

[olcowhand]

One of my welders, an older Century does have a "Force" setting for AC. Don't know the dynamics, but it's for deep penetration & severing steel. Found a rep pic just like my welder.

 

[Propane1]

Jumpins. That would be nice to have. My stick welder has two out puts, but only A/C. 230 on the low and 295 on the high. Just take the positive lead out and switch it to the one you want.
I really don’t know the advantage of it or difference it makes in welds. 135 amp on low or high would be the same thing. I think. But no problem cutting holes in stuff if you want. With the high setting.

Noel

 

[Cvans]

"Force" setting for AC

I'm wondering if it doesn't control the output voltage.

 

[olcowhand]

I'm wondering if it doesn't control the output voltage.

Likely does, as it's wicked hot on "Force". It'll smoke a small rod fast!

 

[Toomanytoys84]

I thought arc force determined the amount of amperage drop that was allowed depending on your arc lenght. If you rod is closer to the metal vs further away.

Someone explained it to me one time but I dont remember. We had a welder underground that had a setting for arc force 0 to 10.

I am no pro welder...probably not even an amateur...I just set my welder by ear and go with what feels right. I can make 2 pieces of metal stick together....

 

[Cvans]

I'm wondering if it doesn't control the output voltage.

This was just a suggestion. It was not based on first hand knowledge.