Well, I have ran into the same problem on a "new" 90 I picked up this week. Using my calibers the little pipe measures out to be .25 (1/4 inch) and I'd like to remake it. I assume this would be "NPT 1/4 18" or that is what I am going to try with a die cutter (getting these bits off Amazon and they are likely cheap China stuff). While it won't be nickel plated, it is small enough perhaps it won't bother me much (plus it is the bottom pipe). A zillion years ago I watched my Dad use Tap & Die for water & gas pipping around our old house, so I more or less understand the concept (but haven't done it myself).
Paula - I little birdie tells me you might have done this? Or perhaps you made a new pipe steamwhistle for your 90? If that is correct, I'd love any information you could provide :-)
Hi Rich,
Are we talking about the pipe nipple that comprises the horizontal portion of the sight glass elbow? If so, my expertise only applies to the B30/B31 style, with the spherical body, though the Model 90 might well use the same nipple. The one for the B30/B31 measures .25"O.D. x .50" long, each end threaded a distance of .15". Here's a picture of a broken one:
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The thread is a 1/4-40 "ME" (Model Engineer) thread. There is also a 1/4-40 "MTP" (Model Taper Pipe), which has a tapered thread. The NPT 1/4-18 you mentioned would be WAY too large, with an O.D. of around 9/16". More information and/or pics would help me understand what you need. I may be able to help.
Paula
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