Accupro 88.711.40.AP CAT40 Retention Knob 5/8-11

Product Description

The ACCUPRO 88.711.40.AP is a CAT40 retention knob designed to secure toolholders in CNC machining center spindles. It threads directly into the drawbar mechanism, clamping the toolholder taper firmly against the spindle seat during cutting operations. This knob features a 5/8-11 thread, a 15-degree angle radius, and a High Torque designation, which supports reliable clamping force in demanding milling and drilling applications. With an overall length of 2.011 inches and a knob diameter of 0.748 inches, it is dimensioned to CAT40 standard specifications. Machinists, tool crib personnel, and CNC setup technicians install this component as part of routine toolholder assembly.

This retention knob is suited for use in vertical and horizontal CNC machining centers equipped with CAT40 spindle interfaces. It applies to production and job-shop environments where toolholder changeovers are frequent and consistent drawbar engagement is critical to runout and surface finish quality. The Style C profile and High Torque designation make it appropriate for applications involving heavier cuts or higher spindle loads where standard retention knobs may not provide adequate clamping force.

Key Features

• CAT40 taper size for compatibility with industry-standard CAT40 spindle toolholders
• 5/8-11 thread size for direct drawbar engagement
• 15-degree angle radius for proper seating geometry
• High Torque designation supports demanding milling and drilling operations
• Style C profile with a neck diameter of 0.5511 inches and flange thickness of 0.7913 inches
• Knob-to-flange length of 1.0275 inches for correct drawbar engagement depth

Compatibility

Designed as a direct-fit retention knob for CAT40 toolholders with a 5/8-11 drawbar thread. Verify drawbar thread specification on the target machining center before installation.

Installation Notes

Retention knobs are installed by qualified machinists or CNC setup technicians. Power down and lock out the machining center spindle before handling any toolholder or retention knob. Use a retention knob wrench or spanner rated for the torque requirements of a High Torque knob; do not use substitutes that could damage the thread or knob geometry. Inspect the drawbar thread for wear or contamination before threading in the new knob.