Mr Lynch was kind enough to loan me the original parts, and I have been studying them some. What is interesting to me is that I am suprised that the engineers who built it and designed the parts didn't (or couldn't) figure out where the rings would fail. Here's the new pics:

Yes, I hot glued the ring back together, I wanted to get a better idea of the curve and the measurements, and the hot glue peels right off. Taint pretty, but it worked. Couldn't hurt it any worse.
The above looks like an original repair to me, they put the bolt hole at the thinnest part of the curve, making a weak spot. Hmm. I wonder if the expansion of the boiler when it was hot caused the rings to flex a bit as well. Cast iron doesn't flex too good apparently.
And this one and the fourth one up show much better the patternmaking challenge I have before me. I have thought of several different methods, though.
Again, this one looks like it was an original repair, not something done recently.
This next bad boy is going to be another challenge, it is the cover that holds the insulation in on the front of the cylinder. The band surrounding it is a repair, I think it was an attempt to keep it from splitting down the side after the chunk came out of the face. You can barely see the part number cast onto the front of it (a partial 93 near the center, the 9 is broken and my camera is old). The repair inside is relatively modern, I think.
I am trying to get a few more projects out of the way, and then I will get back to some serious patternmaking. I am going to redo the hand hole cover pattern I made, after getting a close look at the original and taking some more measurements I don't think my new one is very accurate. If I'm going to do it, I might as well do it right.
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