Jacobs JCM3653P Drill Chuck Key K3C 5/16 in Pilot

Product Description

The JACOBS JCM3653P is a drill chuck key designed to tighten and release drill chucks on bench-top and floor-standing drill presses, lathes, and similar rotating machinery. Designated Key Number K3C, it features a 5/16-inch (0.3100-inch decimal, 7.93 mm) pilot diameter that seats securely into the chuck's pilot hole to prevent slipping during operation. This is a direct OEM-style replacement part suited for maintenance techs, machinists, and tool-room personnel who need a reliable keying solution without sourcing a complete chuck assembly.

This chuck key is intended for use with compatible JACOBS-style chucks in light industrial, maintenance, and workshop environments. It is identified as compatible with product number 34-33C. The K3C designation matches a specific pilot geometry, so confirming the chuck's keyway size before installation is recommended. Typical applications include drill press maintenance in manufacturing facilities, vocational shops, and mechanical service environments where chuck integrity directly affects drilling accuracy.

Key Features

• K3C key number with 5/16-inch pilot diameter for precise chuck engagement
• Decimal pilot diameter of 0.3100 inches (7.93 mm) for close-tolerance fit
• Compatible with product number 34-33C JACOBS-style chucks
• Lightweight at 0.17 pounds for easy single-hand use
• Single-piece replacement unit sold individually

Compatibility

Listed as compatible with JACOBS product number 34-33C. Verify the pilot diameter and key number against your existing chuck specifications before installation.

Installation Notes

Installation is performed by machinists or maintenance technicians familiar with rotating machine tool service. Before servicing a drill chuck, power down the machine completely and confirm the spindle has come to a full stop. Insert the chuck key pilot into the chuck's keyway hole, ensuring a snug fit with no lateral play, and engage the gear teeth fully before applying torque. Do not use a chuck key as a substitute for a chuck wrench on keyless chucks or on any chuck whose keyway diameter does not match this pilot specification.