(This is an archive of updates from 2021. For current updates, an explanation of what this all is, and the reason that a quotation and photograph from 1921 appear above, go one level up.)
Other Center Indicators
2021-02-16. Other? This post grew out of the work reported in my "Instagram vs. the Ents" Workshop Update, above, which looked into two ways to center a punch mark in a workpiece held on the faceplate or in the four-jaw chuck of a lathe. Here we have a more detailed look into these and related devices. It deliberately excludes the category of devices that I'm calling, generically, (Lever) Center Indicators. These get a writeup of their very own, below.
NOTE TO SELF: Finish "By All Indications" post; or, better, revise all of this into a general history of centering indicators. Put this near the yet-to-be-written history of dial vs dial test indicaor.
Instagram vs. the Ents
2021-02-11. Using a spring-loaded tapping guide as a center indicating device on the lathe. Why simple images won't do, and the complexity that we need instead.
(Lever) Center Indicators
2021-02-11. The device I'm calling a (Lever) "Center Indicator" was well-known to late 19th and early 20th century machinists. Starrett called theirs a "Center Tester" (No. 65), Brown & Sharpe called theirs a "Lathe Test Indicator" (No. 736), and several others were described in the journals of the day. A similar device is still in production (by Tallgrass Tools). It is used on a lathe to true up a punchmark on a workpiece held on a faceplate or in an independent four-jaw chuck. I found myself to be more confused by the use of this instrument than others seem to have been, and so of course ended up researching it too deeply.
(This writeup began as a section of the "Instagram vs. the Ents" Update, above.)
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