Accupro 766040 CAT40 Retention Knob St Series 5/8-11

Product Description

The ACCUPRO 766040 is an ST Series short retention knob designed for CAT40 toolholders used in CNC machining centers. It threads into the drawbar at 5/8-11 and secures the toolholder during automatic tool changes. The knob features a 45-degree angle radius, a knob diameter of 0.74 inches, and an overall length of 1.5157 inches. Through-coolant capability is built in via a 0.2913-inch coolant hole, making it suitable for wet-machining applications. Licensed machinists, tool crib technicians, and CNC setup personnel typically install and service these components during toolholder maintenance cycles.

This retention knob is suited for CAT40 toolholders in vertical and horizontal machining centers that use automatic tool changers. It is a direct-fit short-series replacement for worn or damaged retention knobs in shop environments running CAT40 tooling. The 5/8-11 thread size is the standard for CAT40 applications. Through-coolant support makes it compatible with spindles that deliver coolant through the tool. The ST series short design is appropriate where minimal knob protrusion is required by the machine spindle or drawbar configuration.

Key Features

• CAT40 taper size for standard CNC machining center toolholders
• 5/8-11 thread fits standard CAT40 drawbar configurations
• 45-degree angle radius for proper drawbar engagement and pull force distribution
• Through-coolant capable with 0.2913-inch coolant hole diameter
• Short ST Series profile with 0.4401-inch knob-to-flange length
• Pilot diameter of 0.6410 inches for precise toolholder centering

Compatibility

Designed as a direct-fit replacement retention knob for CAT40 toolholders with a 5/8-11 drawbar thread in CNC machining centers equipped with automatic tool changers.

Installation Notes

Retention knobs are typically installed and torqued by qualified machinists or tool crib technicians using a retention knob wrench and appropriate toolholder fixture. Always remove the toolholder from the spindle before servicing the retention knob. Do not overtighten, as excess torque can distort the toolholder taper and affect runout. Verify thread engagement is complete and the knob seats flush before returning the toolholder to service.