The Starrett 685 Series measures chamfers on an outside diameter — the lead-in on a shaft, pin, stud or turned boss — rather than in a hole. It is a direct-measure gage: no setting master, no calculation, the dial reads chamfer diameter.

How It Reads

An external gage measures the smallest diameter of any chamfer whose included angle falls within the range printed on the dial face. (The internal 683/684 gages measure the largest diameter — the two conventions are opposite, and the dial face states which applies.)

Pressed against a flat surface the gage should read the set number stamped on the back of the indicator, and can be adjusted back to it as the blades wear. All ground surfaces are hardened tool steel and the indicator is AGD design.

Choosing a Range

Three inch-reading ranges cover 1/8-1/2", 3/16-1" and 1-2". Note the overlap between the first two — 3/16-1" (685-2Z) is the broad general-purpose range, while 1/8-1/2" (685-1Z) resolves small-diameter work.

Angle Coverage

The 685 covers 0-90° included angles. The 686 Series is the 90-127° external equivalent and can be quoted on request. For chamfers inside a hole, use the 683 (0-90°) or 684 (90-127°) internal gages.

Applications

Turned shaft and pin lead-in inspection, stud and fastener chamfer verification, assembly-fit troubleshooting, incoming and in-process inspection.