Iscar 4503098 Retention Knob CAT40 5/8-11 Thread

Product Description

The ISCAR 4503098 is a CAT40 retention knob designed to secure toolholders in CNC machining center spindles that use the CAT40 taper standard. It threads directly into the toolholder drawbar bore using a 5/8-11 thread and provides the clamping interface between the toolholder and the machine spindle drawbar mechanism. The knob features a 45-degree angle radius at the pull stud head, a knob diameter of 0.74 inches, and an overall length of 1.5 inches. It is installed by machinists and toolroom technicians during toolholder assembly or replacement.

This retention knob is suited for CAT40 toolholders used in vertical and horizontal CNC machining centers operating with 40-taper spindles. It is a direct-replacement pull stud for applications where the existing knob is worn, damaged, or missing. The 0.49-inch neck diameter and 0.64-inch knob-to-flange length are consistent with standard CAT40 pull stud geometry for use with conventional drawbar systems. Through-coolant is not supported by this knob.

Key Features

• CAT40 taper size for compatibility with 40-taper CNC spindle systems
• 5/8-11 thread engages standard CAT40 toolholder drawbar bores
• 45-degree angle radius head for proper drawbar engagement and clamping force
• 0.74-inch knob diameter and 0.49-inch neck diameter meet standard CAT40 pull stud dimensions
• 1.5-inch overall length fits typical CAT40 toolholder retention knob pockets
• No through-coolant passage — solid construction for standard coolant configurations

Compatibility

Designed as an OEM-style replacement retention knob for CAT40 toolholders with a 5/8-11 threaded drawbar bore used in standard 40-taper CNC machining center spindles.

Installation Notes

Retention knobs are installed and torqued by machinists or toolroom technicians during toolholder setup or maintenance. Power down and lock out the machining center spindle before removing or installing any toolholder components. Use a retention knob torque wrench or toolholder fixture to prevent toolholder body damage during installation — do not use impact tools. Inspect the toolholder bore threads for wear or damage before installing a new knob.