Accupro 88.511.50.AP CAT50 Retention Knob 1-8 Thread

Product Description

The ACCUPRO 88.511.50.AP is a CAT50 retention knob designed to secure toolholders in CAT50 spindle tapers on CNC machining centers. Manufactured to Style A geometry with a 1-8 UNC thread, this retention knob delivers a high-torque clamping interface between the drawbar and toolholder. Key dimensions include a 1.14 inch knob diameter, 0.82 inch neck diameter, and a 2.5748 inch overall length. The 45-degree angle radius at the knob head provides consistent seating force distribution across the spindle interface. Weighing 0.25 pounds, it is sized for direct replacement or new toolholder assembly in high-production machining environments. Installation is handled by machinists and CNC setup technicians.

This retention knob is suited for CAT50 toolholders used in vertical and horizontal machining centers running production or job-shop operations. The 1-8 thread pitch is the standard for CAT50 drawbar systems, making this knob applicable across a wide range of CNC spindle configurations that accept CAT50 tooling. The Style A profile is one of the most common retention knob geometries for CAT50 applications, and the high-torque designation indicates the knob is engineered to handle elevated clamping loads without galling or deformation under repeated tool changes.

Key Features

• CAT50 taper interface with 1-8 UNC thread for standard drawbar compatibility
• High-torque rated for reliable clamping under heavy-duty machining loads
• Style A geometry with 45-degree angle radius for consistent spindle seating
• 1.14 inch knob diameter and 0.82 inch neck diameter for proper toolholder fit
• 2.5748 inch overall length with 1.0 inch knob-to-flange and 0.70 inch flange thickness
• Compact 0.25 pound weight suitable for automated tool changers

Compatibility

Designed as an OEM-style replacement or assembly component for CAT50 toolholders using a 1-8 UNC drawbar thread in standard CNC machining center spindles.

Installation Notes

Retention knobs are installed by machinists or CNC toolroom technicians during toolholder assembly. Always ensure the spindle and drawbar are fully de-energized and the machine is in a safe lockout state before servicing toolholders. Apply the correct installation torque using a retention knob wrench or spanner to avoid over-tightening, which can distort the toolholder taper bore. Inspect the knob thread and toolholder bore for chips or contamination before assembly.