The Starrett 684 Series is the wide-angle internal chamfer gage: same direct-measure instrument as the 683, with the dial calibrated for included angles from 90° to 127°. It is the gage to reach for when a chamfer is shallow and wide rather than a conventional 45°-per-side lead-in.

How It Reads

Like every gage in the Starrett chamfer family, the 684 needs no setting master. Pressed against a flat surface it should read the set number stamped on the back of the indicator, and it can be adjusted back to that number as the blades wear. The three-blade plunger locates on the chamfer face and the AGD dial reports chamfer diameter directly.

An internal gage measures the largest diameter of any chamfer whose included angle falls within the range printed on the dial face.

Choosing a Range

Four inch-reading ranges cover 0-3/8", 0-1/2", 0-1" and 1-2". Select the range that brackets the diameter under inspection.

683 or 684-

The two series differ only in the angle band on the dial. Use the 683 Series for included angles of 0-90°, and the 684 for 90-127°. If the print calls a specific countersink angle — 82°, 90° or 100° — a countersink gage that seats on the angular face is the better instrument, because it reads the large diameter of the countersink rather than the chamfer edge.

Applications

Wide lead-in and shallow chamfer inspection, valve and seat work, hydraulic and pneumatic port qualification, incoming and in-process inspection.