Spi 21-152-4 Countersink Gage 100 Degree

Product Description

The SPI 21-152-4 is a precision countersink gage designed to verify the angle and depth of countersunk holes in machined workpieces. Built from hardened tool steel, it delivers an accuracy of 0.0005 inches, making it a reliable instrument for quality control and inspection workflows. The gage checks 100-degree countersink angles, a common specification in aerospace and general manufacturing fastener applications. Machinists, toolroom inspectors, and quality technicians use this type of gage to confirm that countersunk features meet drawing tolerances before assembly or finishing operations proceed.

This countersink gage is suited for use in machine shops, fabrication facilities, and inspection departments where fastener hole geometry must be verified to tight tolerances. The 100-degree angle is frequently specified for flush-mount fastener installations in sheet metal, aluminum, and structural components. It is appropriate for both production floor spot-checks and formal first-article inspection processes. The hardened tool steel construction supports repeated use in demanding shop environments without significant wear to the contact surfaces.

Key Features

• Measures 100-degree countersink angles for common flush-fastener applications
• Accuracy of 0.0005 inches for reliable, repeatable inspection results
• Hardened tool steel construction resists wear during extended production use
• Compact form factor suits bench inspection and in-process checking at the machine

Compatibility

Designed for inspecting 100-degree countersunk holes in machined metal workpieces typical of general manufacturing and fabrication environments.

Installation Notes

This is a precision measurement instrument, not an installed component. Handle with care to avoid dropping or contact with abrasive surfaces that could damage the hardened steel contact faces. Clean the gage and the workpiece surface before measuring to prevent debris from introducing error. Store in a protective case away from other tooling to maintain calibration integrity.