welding

[Mlmartin15]

ok so whos ever welded cast iron, i have a yoke for a bell to fix, the brake is a flat space about 4 inches wide, i know i will need to heat it up slowly to about 600, then weld with cast iron rods, then slowly cool, im just asking if theres any little tips, or maybe even brass braze it up, have lots of welding time under my belt, but have never brazed or welded cast iron, the yokes large about 18 - 24 inch's across, havent seen the bell but with the large yoke i am asuming its big

[Dr Dean]

Preheat to 400 weld with nickel rod then post heat to 400 and bury in new floor dry to cool slowly.

[agsolder]

I would not trust a piece of welded cast iron any farther than I could throw it. If there is the slightest chance the bell could fall and hurt somebody when the yoke breaks again, which it will, the present break indicating a basic design flaw, then I'd say drill the yoke and join it together with gusset plates on each side. Or forge a brand new yoke out of appropriate plate. Nobody will notice and you will sleep better.

[evfreek]

There is a really good reference book on torch welding near the end of the free blacksmithing books on the web thread. It says cast iron is the easiest thing to weld with a torch. The procedure that is given is full of very practical details (unlike a lot of those old books which are pedantic and sometimes barely relevant). Two of the key points are keeping the metal hot and managing contraction stresses in complicated geometry's. It even tells how to make a blown propane pipe burner to do the preheat.

I successfully welded a cast iron vise base by following some instructions from Ernie L on the web (stagesmith). He is a real welding guru. He says preheat softly, peen, cool slowly. If I recall correctly, he says 500F with a tempilstik, not red, and peen hard enough that you think that you will break the casting. That is because, as the weld cools, the contraction will break the cast iron around the weld unless you force the weld to take up some of the expansion.

Anyway, try those two resources. They sound reasonable.

[Mlmartin15]

thanks guys, I have considerd making the new yoke and kinda want to, but will try to fix the original, its a friends bell and has sintamintal value (sorry i cant spell). so im hoping to repair it, but if my weld fails ill forge a new yoke