I was under the impression that the threaded portion of the shut-off rod must be removed for proper lapping.
After several unsatisfactory attempts, I found that the most leakage was indeed a problem of alignment.
But the factory alignment tool has a serious flaw: metal must be bent passed true so that it can relax back to true, and smacking the tool with a hammer just doesn't cut it!
So I machined a tapered tap for the threaded bung, and drilled and honed the center for a ground 1/4" pilot rod:
Just looking through the hole gives a great indication of mis-alignment.
The pipe to the left in the picture has a top cap brazed into it. This can be used to massage the top of the tank when necessary, and the long tap at the bottom can be used to force the bottom straight as well, until the pilot rod slips through smoothly.
But even with a lapped and aligned petcock, I have alwasy relied upon a pair of pliers ground to safely clear the paint to snug things up if the machine was to sit for an extended period of time.
PS: Thanks Kyle!
Now I have one more item to use to whittle down my hoard of PEEK scrap!
PhenylEthylEthylKetone is the greatest stuff invented since flaked flint.
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