Seco 03119963 Retention Knob CAT40 5/8-11 Thread

Product Description

The SECO 03119963 is a CAT40 retention knob designed to secure toolholders in CNC machining center spindles. It threads into the drawbar pull stud socket of the toolholder, transmitting clamping force from the spindle's drawbar mechanism to hold the assembly firmly during cutting operations. This knob features a 5/8-11 thread, a 45-degree angle radius on the pull stud head, and a through-coolant port to support coolant-through tooling setups. With an overall length of 1.626 inches and a knob diameter of 0.74 inches, it is a direct-fit replacement sized to CAT40 taper standards. Installation is performed by CNC machinists and toolroom technicians as part of routine toolholder assembly or replacement.

This retention knob is suited for CAT40 toolholders used in vertical and horizontal machining centers across production shops, job shops, and toolrooms. The through-coolant feature makes it compatible with setups where coolant is delivered through the spindle centerline to the cutting tool. It is commonly installed during toolholder reconditioning or when replacing worn or damaged pull studs. Packaged individually, it allows single-unit replacement without requiring a full toolholder kit.

Key Features

• CAT40 taper size for use with standard CAT40 toolholders
• 5/8-11 thread size for drawbar engagement
• 45-degree angle radius on knob head
• Through-coolant port supports centerline coolant delivery
• Neck diameter of 0.488 inches and knob-to-flange length of 0.642 inches for precise fit
• Compact overall length of 1.626 inches

Compatibility

Designed as a direct-fit replacement retention knob for CAT40 taper toolholders accepting a 5/8-11 threaded pull stud with a 45-degree angle radius.

Installation Notes

Retention knobs are installed by machinists or toolroom technicians during toolholder assembly or maintenance. Always remove the toolholder from the spindle and release drawbar pressure before replacing a retention knob. Use the correct torque wrench and retention knob installation socket to achieve proper seating — do not use pliers or improvised tools that may damage the thread or knob geometry. Inspect the toolholder thread bore for wear or damage before installing a new knob.