Parlec 4008TRK Retention Knob CAT40 5/8-11 Thread

Product Description

The PARLEC 4008TRK is a CAT40 retention knob designed to secure tool holders in CNC machining center spindles. It threads into the drawbar mechanism to pull and lock the tool holder taper firmly against the spindle face during operation. With a 5/8-11 thread, a knob diameter of 0.744 inches, and an overall length of 2.06 inches, this knob meets common dimensional standards for CAT40 tooling systems. Style C geometry and a 75-degree angle radius are machined to precise tolerances, ensuring consistent seating and reliable clamping force. Installation is straightforward for CNC setup technicians and toolroom machinists.

This retention knob is used in CAT40 tool holder assemblies on vertical and horizontal machining centers. It is suited for production environments where tool changes are frequent and secure holder retention is critical to dimensional accuracy and spindle safety. The 4008TRK is a toolroom and shop-floor staple for facilities running CAT40 tooling, applicable in both job-shop and high-volume manufacturing settings.

Key Features

• CAT40 taper size for compatibility with standard CAT40 tool holders
• 5/8-11 thread engages drawbar mechanism for positive clamping
• 75-degree angle radius for proper seating geometry
• 0.744 inches knob diameter with 0.635 inches pilot diameter for accurate centering
• Knob to flange length of 1.024 inches and flange thickness of 0.28 inches for consistent stack-up dimensions
• No through-coolant configuration, suitable for dry or flood coolant setups without internal passages

Compatibility

Designed as an OEM-style replacement retention knob for CAT40 tool holders used in standard CNC machining center spindles requiring a 5/8-11 drawbar thread.

Installation Notes

Retention knobs should be installed by a qualified CNC machinist or toolroom technician. Always ensure the machine is powered down and the spindle is locked before removing or installing a retention knob. Use the correct torque wrench and follow the tool holder manufacturer torque specifications to avoid under- or over-tightening, which can damage the drawbar or affect runout. Inspect the knob threads and tool holder bore for damage or contamination before assembly.