Haimer 88.613.40 Retention Knob CAT40 5/8-11 Thread

Product Description

The HAIMER 88.613.40 is a CAT40 retention knob designed to secure toolholders in CNC machining center spindles with an automatic toolchanger (ATC). It features a 5/8-11 threaded shank for direct engagement with the toolholder drawbar and a 45-degree angle radius on the knob head for positive ATC gripper contact. Overall length is 2.25 inches. The 0.1378-inch coolant hole diameter supports through-coolant delivery directly to the cutting zone, making this knob suitable for high-speed milling, drilling, and tapping operations where coolant-through toolholders are in use. Machinists, tool crib technicians, and CNC setup personnel are the primary installers.

This retention knob is used in CAT40 toolholders installed in vertical machining centers (VMCs), horizontal machining centers (HMCs), and other CNC spindles that accept CAT40 taper tooling. It is appropriate for both production shop and job-shop environments running automatic toolchangers. The through-coolant feature makes it well suited for deep-hole drilling, high-pressure coolant applications, and extended-reach toolholder assemblies where direct coolant delivery is required at the spindle interface.

Key Features

• CAT40 taper size for compatibility with standard CAT40 toolholders
• 5/8-11 thread engages directly with the machine drawbar
• 45-degree angle radius on knob head ensures reliable ATC gripper engagement
• Through-coolant capable with a 0.1378-inch coolant hole diameter
• 0.59-inch knob diameter and 0.39-inch pilot diameter for proper spindle alignment
• Compact overall length of 2.25 inches with a 1.27-inch knob-to-flange dimension

Compatibility

Designed as a direct-fit retention knob for CAT40 taper toolholders used in CNC machining centers equipped with automatic toolchangers and 5/8-11 drawbar threads.

Installation Notes

Retention knobs are installed and torqued by machinists or toolroom technicians using a retention knob wrench and a toolholder holding fixture - never torque against the spindle taper directly. Always de-energize and lock out the machine before handling toolholders in the spindle. Verify the drawbar thread (5/8-11) matches the machine specification before installation. Inspect the knob and toolholder threads for wear or damage before each assembly; a loose or cross-threaded knob can cause toolholder pull-out during a cut.