welding cast with nickle rod

V-grind the cracks out. Preheat to about 600 DegF or until a drop of oil smokes lay in short stiches, peaning each as it cools. slow cool by burying in powdered lime, vermiculite or wrapped in a wool blanket.

The idea is to expose some clean metal to stick the nickle to, and to difuse the nickle as little as possible into the base metal.

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Could you elaborate on what is meant by peening? Whack it with a 12 lb. sledge hammer? Tap on it with a welding slag hammer? What I did last time, take a center punch and carpenter hammer and put several punch marks in the weld? Other?

Karl

You will have a difficult time with a spoked unit. The contraction and restraint is complicated. They are difficult enough to cast let alone weld. Sometimes you have to fracture the rim, weld the spokes. then weld the rim. You might try first to weld the spokes with short nickel rod welds bead in veed out cracks. Peen with a small ball peen until cold enough to touch with a bare hand. Often what happens is the rim restrains the spoke and the spoke fractures again. The cracks sometimes are a result of stresses that have been in the casting since manufacture. Randy

Peening is tapping it, hard, with the pointy end of a chipping hammer. This expands the nickel as it cools. The nickel will shrink at a far greater rate than the cast, and the shrinkage will make it pull away from the cast and cause a crack at the transition zone. Peening counters the shrinkage. The other points Karl made are important. Short beads. Let it cool between beads. Don't burn into the parent metal; the cast welding is more like brazing. Diluting the weld with cast will make it really brittle. The cast has to be clean: no oil in it. If it's a crankcase it needs to be baked until the oil has carbonized.

Dan

"Randy Zimmerman" wrote in news:Lh0Xc.211144$J06.34146@pd7tw2no:

Being as how I am doing this job for 5 bucks + cost of the rods, it's beginning to look like an experiment in futility, the thing weighs about

100# and is bigger than my work bench. The client has a spare in case this one breaks but I would really like to do it up right. Thanks to all for the advice!

granpaw

I seem to recall reading somewhere that this is the reasoning behind the graceful "S" curved spokes in the old cast flywheels and pulleys. Gerry :-)} London, Canada

Only know how I've done it. I both pre heated and beveled on most cast welding with NiRod. Use lower amperage than you'd use with equivalent size mild steel rod. How big are these spokes? Small section stuff probably doesn't benefit from preheat. OTOH, you may want to try to preheat the rim so that the whole thing will shrink together. Is the wheel a single casting, rim, spokes and hub?

bob g.

I don't know that the nickel shrinks so much more than the cast it's just that all the hot stuff (nickel and adjacent cast) shrinks while the rest of the casting doesn't. (could be wrong about this)

rhg

Dan Thomas wrote:

Keep us posted on how this goes. I've also repaired a fair number of castings with acetylene and silver solder. So called silver brazing is stronger than cast. Acetylene heats a greater area but the temp is quite a bit lower.

bob g.

Gerald Miller wrote:

I like 99% nickel rods and do just a spot and let it cool completely and then weld some more. Object is to not get it hot and slow cool.

I've managed to be surprisingly lucky in cast iron welding with 99% nickel and a little 110V welder. Biggest thing to remember is lots of peening as the bead cools. So far I've done some machine parts and a recently-broken lathe dog without trouble.

GTO(John)