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

Product Description

The PARLEC 4008TRKC is a Style C retention knob designed for CAT40 taper toolholders used in CNC machining centers. It features a 5/8-11 thread and a 75-degree angle radius, providing secure engagement with the machine spindle drawbar. The knob measures 2.06 inches overall length with a 0.744-inch knob diameter and includes a through-coolant passage with a 0.276-inch coolant hole diameter. Licensed machinists and toolroom technicians install this component when setting up or replacing toolholder retention hardware on CAT40-compatible spindles.

This retention knob is used in horizontal and vertical machining centers equipped with CAT40 spindle interfaces. The through-coolant design supports flood and through-spindle coolant delivery, making it suitable for applications where coolant-through tooling is used. The 0.635-inch pilot diameter and 0.549-inch neck diameter match CAT40 toolholder bore geometry. A knob-to-flange length of 1.024 inches and flange thickness of 0.280 inches ensure proper seating and drawbar pull force engagement during tool clamping cycles.

Key Features

• CAT40 taper size for compatibility with standard CAT40 toolholders
• 5/8-11 thread engages directly with machining center drawbar hardware
• 75-degree angle radius for consistent drawbar contact geometry
• Through-coolant capable with 0.276-inch coolant hole diameter
• Style C knob profile with 0.744-inch knob diameter
• 2.06-inch overall length with precisely dimensioned pilot and neck diameters

Compatibility

Designed as an OEM-style replacement retention knob for CAT40 taper toolholders used with standard 5/8-11 drawbar systems in CNC machining centers.

Installation Notes

Retention knobs are installed and serviced by machinists or toolroom technicians. Power down and lock out the machining center spindle before removing or installing any toolholder retention hardware. Use a calibrated torque wrench and follow the machining center manufacturer's specified torque value for the drawbar and retention knob interface. Inspect the knob threads and toolholder bore for damage or contamination before installation.