Accupro 88.615.50.AP Retention Knob CAT50 1-8 Thread

Product Description

The ACCUPRO 88.615.50.AP is a CAT50 retention knob designed to secure toolholders in CAT50 spindle tapers on CNC machining centers. It threads into the toolholder drawbar interface using a 1-8 UNC thread and provides the clamping force needed to hold the toolholder firmly during cutting operations. The knob features a high-torque design and a 60-degree angle radius, which distributes clamping load evenly across the spindle interface. Overall length is 3.3524 inches, knob diameter is 0.9055 inches, and the part weighs 0.25 pounds. Machinists and CNC maintenance technicians install and replace these knobs as part of routine toolholder maintenance.

This retention knob is used in CNC milling and machining center applications wherever a CAT50 spindle interface is present. CAT50 is common in heavy-duty production environments running larger spindle machines. The knob installs directly into the pull stud pocket of the toolholder. Key dimensional references for this application include a knob-to-flange length of 1.7776 inches, a flange thickness of 1.3839 inches, and a neck diameter of 0.6693 inches. Through-coolant is not supported on this part. Style C configuration is used.

Key Features

• CAT50 taper size for use in heavy-duty CNC machining center spindles
• 1-8 UNC thread for direct engagement with toolholder drawbar interface
• High-torque design for increased clamping force and toolholder retention
• 60-degree angle radius distributes clamping load across the spindle contact surface
• Style C configuration with 0.6693 inch neck diameter for proper fitment clearance
• No through-coolant, suitable for dry or external coolant machining setups

Compatibility

Designed as an OEM-style replacement retention knob for CAT50 toolholders requiring a 1-8 UNC thread pull stud with Style C geometry.

Installation Notes

Retention knobs are installed and serviced by CNC machinists or machine tool maintenance technicians. Always remove the toolholder from the spindle and ensure the machine is in a safe, powered-down state before replacing a retention knob. Use the manufacturer-specified torque wrench and retention knob socket to achieve proper seating — do not use impact tools. Inspect the toolholder threads for wear or damage before installing a new knob.