Cast iron welding questions

So I have this charity job for the WA state parks dept. A pulley on an old compressor was broken by some kids when they tipped the compressor
over and I was volunteered to repair it. The repair is just for looks, the compressor will never be run. But it will have kids tugging on it so the welds must be sound. My original plan was to build an oven around the pulley out of ceramic cloth, the stuff they make kilns out of, heat it up, and use silicon bronze rod to tig weld it. I know this works, I have done it more than once. The pulley is about a foot in diameter which is why it needs to be surrounded with the ceramic insulation. Anyway, this pulley will be painted after the repair but the paint will get worn off and the repairs will show. THe compressor is part of a hands on display of an old gas station and is original. Is there a tig rod that can be used on cast iron that has a pretty good color match? I could stick weld the thing but I'm kinda rusty at precision stick welding and I am trying to keep the welds as small as possible. I will be vee-ing out all the breaks so there will be pretty big welds but I still want to be able to have as little as possible. I will be doing handwork on the welds to blend them in after welding. The pulley is an antique which is why the thing is being welded in the first place and not just replaced. Furthermore, our state parks department is strapped for cash so they can't even spend the time looking for a replacement. Thanks, Eric
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On Thu, 20 Dec 2012 16:50:26 -0800, snipped-for-privacy@whidbey.com wrote:

Stainless will stick and be a much better color match that bronze.
One potential problem is that while you intend this to be a cosmetic only repair, you don't know that others in the future will do. Someone else might try to 'restore' and run the compressor years from now. An obviously incomplete repair (V grove with big strong tacks) might be safest over all.
Just some idle thoughts...
--
William

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On Thu, 20 Dec 2012 20:24:05 -0500, William Bagwell

Yes, you are right. Someone may decide to run the compressor in the future. This will not be a problem though because a proper job, and I intend to do a proper job, will be plenty strong. Stainless steel will stick well but is not a good enough color match. I'm hoping for some rod that will blend in better, maybe even rust a little like the cast iron will because the pulley is exposed to the weather. Eric
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The easiest way to fix it is to use a little preheat and Nickel-99 stick welding rods. Easy as pie.
i

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I'll attest to the Nickel rod - black it is - works nicely. I did some iron flanges (pipe) to steel. Martin
On 12/20/2012 9:02 PM, Ignoramus28617 wrote:

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My favourite cast repair rod is simple steel stick electrodes marketed as Feroweld or FE or similar. The deposit is VERY hard and non machinable or drillable, but can be easily ground to shape using common grinding disks. I have had good results by preheating and slow cooling and using short passes to limit heat build-up. I use an air powered needle scaler to peen the welds between passes and on the top pass while still hot to limit contraction forces. The finished weld is a good color match with common cast iron and the weld will rust.
I do not like any of the nickel rods sold for cast iron repair and only use them if the repair needs to be machined or drilled. FE rods are a LOT cheaper than nickel.
Good Luck, YMMV
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A second thought, are you sure this pulley is actually cast iron and not cast steel? The grain of the fracture is a good indicator, but I would also use a cutting torch in the area you will be removing to form the weld vee and test if the iron will actually cut or just melts and blows away. Cast steel is a lot easier to weld than cast iron
Good Luck, YMMV
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On Thu, 20 Dec 2012 16:50:26 -0800, snipped-for-privacy@whidbey.com wrote:

As somebody else notes you can tig it using stainless rod. However, the stainless bead will be very hard as the filler metal will absorb carbon from the cast iron. Of course, if you are going to only grind the weld bead down to look smooth there is no problems.
--
Cheers,
John B.
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The only filler I know of that will have a perfect color match to cast iron is....cast iron.
The problem is to use cast iron filler rod you have to gas weld the cast iron. It does work and will match the base metal better than any other rod. I have a selection of cast iron rods. They are narrow cast square rods.
For cosmetics I would just use the bronze rod. Stainless steel or nickel rods require more heat and that may cause more problems than you already have. Enough good enamel spray paint and the bronze will never show.
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