Techniks 21003-90 Retention Knob CAT40 5/8-11 Thread

Product Description

The TECHNIKS 21003-90 is a CAT40 retention knob designed to secure toolholders in CNC machining center spindles that use the CAT40 taper standard. It threads into the drawbar mechanism at 5/8-11 thread and features a 90-degree angle radius at the knob head for positive seating against the drawbar. The knob measures 0.59 inches in diameter and 2.25 inches in overall length, with a total weight of 0.15 pounds. This component is installed by machinists and toolroom technicians as part of routine toolholder assembly or replacement in vertical and horizontal machining centers.

This retention knob fits CAT40 toolholders used in standard machining center applications. It is suited for shops running production milling, drilling, or boring operations where reliable toolholder retention is critical to spindle performance and tool runout. The 5/8-11 thread pitch is the standard for CAT40 drawbar engagement. Replacement of worn or damaged retention knobs is a routine maintenance task performed during toolholder inspection or after spindle crashes.

Key Features

• CAT40 taper size for compatibility with CAT40 toolholder shanks
• 5/8-11 thread engages standard CAT40 drawbar mechanisms
• 90-degree angle radius provides consistent seating against the drawbar pull stud recess
• 0.59 inch knob diameter within standard CAT40 dimensional specs
• 2.25 inch overall length fits standard toolholder retention knob pockets
• Lightweight at 0.15 pounds for minimal added mass in high-speed spindle applications

Compatibility

Designed as a replacement retention knob for CAT40 toolholders requiring a 5/8-11 threaded pull stud with a 90-degree angle radius head.

Installation Notes

Retention knobs should be installed by qualified machinists or toolroom personnel using a proper retention knob wrench to achieve correct torque without damaging the toolholder threads. Always remove the toolholder from the spindle and secure it in a vise or holder block before installing or removing the retention knob. Inspect threads on both the knob and toolholder for wear or damage before assembly. Do not use impact tools on retention knobs, as over-torquing can cause thread stripping or knob fracture.