Adjusting a Lufkin 680A Inside Micrometer

Joseph Gwinn · 2006-12-29T17:10:13+00:00

I recently bought a very used but complete Lufkin 680A Inside Micrometer set (for bores from 1.5" to 8" diameter, resolution 0.001"). I don't know how old it is, but the holder has a patent number on it (1,615,488, issued 25 Jan 1927), so it's probably from the 1930s. It looks it. Anyway, I've been cleaning and adjusting it. Everything was a few thousandths short, largely due to wear at the contact tips (which do not appear to be hardened). The extension rods are easily adjusted with a wrench, but how to adjust the micrometer core (screw and scale) is less clear. I tried to find a patent number for the micrometer itself, but didn't succeed. That isn't to say that none exists. Does anybody know anything about this micrometer? Joe Gwinn

Dec 29, 2006 Last reply: 6 years ago 21 Replies

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Joe Gwinn 5 years ago

I don't know that I do, but US Patent number 1,424,383 is the key.

Enter US1424383 to Google Patents to get a copy.

Joe Gwinn

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