Mitutoyo 146-231 0-1in 0.0001in Groove Micrometer

The Mitutoyo 146-231 is a new Series 146 groove micrometer designed to measure the width and depth of grooves, keyways, and slots inaccessible to standard outside micrometers. It features a 0–1 inch measuring range with 0.0001 inch graduation and a narrow, extended spindle with a ball-type contact point that seats into grooves as small as those found on shafts, bores, and precision-machined components. The thimble scale reads in inch units with a vernier graduation for 0.0001 in resolution, and the tool ships from Mitutoyo's factory calibrated and NIST-traceable, accompanied by a Mitutoyo America Calibration Lab Certificate of Calibration (Code No. 146-231, issued February 2026, showing 0.0000 in error across all tested ranges from 0.219 to 1.000 in). Stored in the original Mitutoyo fitted case with VCI corrosion-inhibitor paper, this instrument is suited for quality control and inspection work where groove width on shafts, retaining ring grooves, keyways, or similar features must be precisely measured.

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