The fact that a piece has broken away w/o distorting the rest would to me suggest it is cast iron, cast steel should be more ductile and bend before it breaks. For the repair I'd braze a piece of mild steel in, that avoids most of the problems cast iron has with welding. Second choice would be preheating and O/A welding with cast iron filler rods, either build it up only using filler rod or weld in a piece of cast iron from something else - mixing materials is less suitable for welding. Pack in dry ashes or similar after welding for a slow cooldown. Electric welding is always a compromize when working on cast iron, the quick cooldown causes the creation of very hard iron carbide around the weld (no matter what rods you use) making it very hard or even impossible to machine. I'd avoid it as long as possible.
I have an oven I use for curing my powder-coated parts. I was planning on using it to preheat the part and to slowly cool down after welding. It has a maximum of 600 degrees farenheit. 700 to 800 is recommended for cast iron, but I think this should work. I'll drop the temperature in the oven 10 degrees each 10 minutes, which I hope will be satisfactory.
Hi Tub If you weld in a piece you need to make sure that the new part is not narrower than the rest of the groove, or it might raise heck with your belt ?
Tubman,good on you for fixing things.sometimes it's what you have to do in order to do. I got the rod from mc Mastercaar .i think it was. Like 30 bucks for a 1/2 pound. If you fit it with a steel piece the rod should do just fine. It gives a very detailed description in their catalogue on its property's. They deliver in one day so that's a no brainier as well. If you think it's going to be really out of balance,try a static type of balancer,think lawnmower blade type. It will get you in the game. Good luck, Gary
The welding of cast stuff is delicate matters. And I hold of doing it till I know it serves a purpose. I would be a little un easy to trust a welding in casting. But I would do an over size weld and smooth it out. Because smooth is stronger! !! My brother worked as an mechanic of big vessels and big ships, and to his best experience, welding old motor parts, they ran stainless electrodes. Thy was less sensitive to oil, dirt, coolant and in perfections in the material. Welding cast is an delicate art. I would only expect an good result I'd you could find a guy to teach you. I work with welding and heavy construction, and I would consider it to "just" metal, but needs some skill to do!