Jacobs 31138 Drill Chuck 3/8 in Threaded Mount 3/8-24

Product Description

The JACOBS 31138 is a keyed drill chuck rated for a maximum capacity of 3/8 inch, designed for threaded mounting with a 3/8-24 thread interface. Built from steel with a plain bearing, this chuck accepts round-shank bits and accessories from a minimum of 0.0394 inch up to 0.375 inch in diameter. The K30 key provides positive clamping engagement, making it a reliable choice for production drilling and general-purpose hole-making applications. Closed length measures 2.5 inches, and the sleeve diameter is 1.43 inches, giving technicians and machinists a compact profile that fits standard drill press spindles and portable drill drivers with matching thread specifications.

The JACOBS 31138 is suited for use on benchtop and floor-standing drill presses, CNC drilling heads, and portable corded drill drivers that accept a 3/8-24 threaded spindle. It is a practical replacement or spare chuck for light industrial, fabrication shop, and maintenance-repair-operations environments. Machinists, maintenance technicians, and tool room personnel are the typical installers. The keyed design is preferred in applications where consistent clamping force and bit retention under repeated use are required over the convenience of a keyless chuck.

Key Features

• Maximum capacity of 3/8 inch (0.3750 inch decimal) accommodates a wide range of standard twist drills and accessories
• 3/8-24 threaded mount for direct installation on compatible drill press and portable drill spindles
• Keyed design with K30 key for firm, repeatable clamping without slippage under load
• Steel chuck body with plain bearing construction for durability in general-purpose drilling
• Compact closed length of 2.5 inches minimizes spindle-to-workpiece distance
• Sleeve diameter of 1.43 inches provides a secure grip surface during key tightening

Compatibility

Designed as a direct-fit replacement for drill presses and portable drill drivers equipped with a 3/8-24 threaded spindle interface. Verify spindle thread size and direction before installation.

Installation Notes

Installation is performed by machinists or maintenance technicians familiar with rotating tool equipment. Power down and lock out the drill press or tool before removing the existing chuck or installing a replacement. Use the K30 key to fully seat and tighten the jaws after mounting the chuck onto the spindle. Confirm the chuck runs true before returning the equipment to service; excessive runout may indicate improper seating on the spindle threads.