Mitutoyo 131-166 Mechanical Spline Micrometer 1 in

Product Description

The MITUTOYO 131-166 is a mechanical spline micrometer designed for precision measurement of splined shafts, keyways, and other narrow-profile features that standard anvil micrometers cannot access. With a 0.25 inch spindle diameter, the 131-166 reaches into tight geometries while maintaining an accuracy of 0.00015 inch and a graduation resolution of 0.0001 inch. The measurement range extends to 1 inch. This is a fully mechanical instrument with no digital counter, making it well suited for shop floor environments where battery dependency is a liability. Machinists, tool and die technicians, and precision metrology professionals are the primary users.

The 131-166 is applied in manufacturing and inspection environments where internal spline diameter, slot width, or groove depth must be verified to tight tolerances. Typical use cases include quality control inspection of power transmission components, verification of splined bores on gearbox components, and incoming inspection of precision-machined parts. The 0.0001 inch graduation makes it appropriate for work requiring close conformance to engineering drawings in both production and maintenance settings.

Key Features

• Mechanical operation with no digital counter — no batteries required
• 0.0001 inch graduation for fine resolution readings
• Accuracy rated to 0.00015 inch
• 0.25 inch spindle diameter accesses splines, keyways, and narrow slots
• Measurement range up to 1 inch

Compatibility

Designed as a direct-use precision measuring instrument for inspection of splined shafts, keyways, and narrow-profile features within a 1 inch measurement range. No specific equipment compatibility is stated by the manufacturer for this SKU.

Installation Notes

Micrometer instruments require no installation but should be handled and stored according to standard metrology practices. Allow the instrument to thermally stabilize to ambient shop temperature before use to minimize thermal expansion error. Clean measuring faces with a lint-free cloth before and after use. Calibrate against a certified gage block or master setting standard before beginning a measurement run, and verify zero before each session.