Have not been making much progress lately... The weather was so nice here in late Spring, that I've been working outside on the house and yard. Had a new roof put on in early June! But it seems we've now returned to our default Summer weather: hot and extremely muggy, punctuated by late-afternoon downpours. Our climate is officially classified as "Humid-Subtropical", after all. Anyway, the upside is that I am spending more time indoors, and making some progress on the Doll.
Next on the list is plugging the open hole in the boiler where the original drain valve once was:
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The original valve probably looked similar to this:
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One option was to simply plug the hole, with either a soldered or threaded plug. But this beautiful engine seems worthy of a better solution than that. I suppose a replica could be machined, though it's a tricky design (with a swaged stem), and is more of a challenge than I want to take on. And it would probably leak anyway. (By the way, if anyone has a spare valve like this laying around, I'd be willing to take it off your hands.
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The compromise I arrived at was to install a commercially-made valve, specifically the GV3MTP Globe Valve from PM Research. For those who don't know, these are extremely well-made, and quite authentic to full-size valves:
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Also, they are made in a 3/16-40 tapered pipe size, which is very close to the size of the hole in the boiler. Only downside is that the price is in line with their quality! Anyway, it's only money.
I was able to fashion a facsimile of the curved snout of the Doll valve. I modified a 3/16-40 brass plug to accept a curved piece of 1/8" O.D. piece of copper tubing. The curved copper tube was soldered into the modified plug, and then threaded into the new valve. Then I drilled out the broken piece of the original valve that remained in the boiler bushing, and tapped the hole with a 3/16-40 MTP tap.
To make the finished "faux" valve look less obvious, I treated it with a Birchwood-Casey product called "Brass Black":
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This worked better than I expected! While it doesn't look exactly like the original, it certainly looks better than a plugged hole would:
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With that part of the restoration complete, it's time to see what I can do about the boiler filler cap. The threads are extremely worn, such that it wouldn't take much twisting to completely strip the threads. The design is rather week in this regard, not having a proper threaded bushing soldered into the boiler. There are only a few threads in the cone-shaped top of the boiler, which also makes it difficult to get a good seal:
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(More to come...)