Accupro 88.611.50.AP Retention Knob CAT50 1-8 Thread

Product Description

The ACCUPRO 88.611.50.AP is a CAT50 retention knob designed to secure toolholders in CAT50 spindle interfaces on CNC machining centers. It threads into the toolholder drawbar at a 1-8 UNC thread and pulls the holder firmly into the spindle taper during tool changes. The knob features a 45-degree angle radius, a knob diameter of 0.9055 inches, and an overall length of 3.3524 inches. The Style C profile and high-torque designation make it suited for demanding milling and boring operations where positive retention and repeatability are critical. Licensed machinists and CNC maintenance technicians are the primary installers.

This retention knob is used in CAT50 toolholding systems on vertical and horizontal CNC machining centers in production and job-shop environments. CAT50 is a common spindle interface in heavy-duty machining applications where larger toolholders and higher spindle torque are required. The knob seats against the flange with a flange thickness of 1.3839 inches and a knob-to-flange length of 1.7776 inches, providing consistent pull-stud geometry for automatic tool changers. The neck diameter of 0.6693 inches is sized for standard CAT50 drawbar engagement.

Key Features

• CAT50 taper size for heavy-duty CNC spindle interfaces
• 1-8 UNC thread size for standard CAT50 drawbar compatibility
• 45-degree angle radius for secure seating and positive retention
• High-torque rated construction for demanding milling and boring operations
• Style C profile meets standard CAT50 pull-stud geometry requirements
• Compact 0.9055-inch knob diameter with 0.6693-inch neck for precise drawbar fit

Compatibility

Designed as an OEM-style replacement retention knob for CAT50 toolholders used in CNC machining centers with CAT50 spindle interfaces and 1-8 UNC drawbar threads.

Installation Notes

Retention knobs are installed by CNC machinists or tool-crib technicians using a retention knob wrench and appropriate torque tool. The spindle must be powered down and the tool changer disabled before servicing any toolholder or pull stud. Do not overtighten the retention knob, as improper torque can distort the toolholder taper and affect runout. Inspect the knob threads and toolholder bore for damage or contamination before installation.