Parlec MH500TRKC Retention Knob CAT50 1-8 Thread

Product Description

The PARLEC MH500TRKC is a Style B retention knob designed for CAT50 toolholders used in CNC machining centers. It threads into the drawbar mechanism at 1-8 UNC to secure the toolholder during automatic tool changes. The knob measures 2.32 inches overall length with a 0.904-inch knob diameter and a 90-degree angle radius at the head. Through-coolant capability is built in via a 0.25-inch coolant hole diameter, making it suitable for high-pressure coolant delivery directly through the spindle. Machinists and toolroom technicians install this component as a direct interface between the machine spindle and the toolholder assembly.

This retention knob is used in CAT50 toolholder applications on vertical and horizontal machining centers equipped with automatic tool changers. The 1-8 thread pitch is standard for CAT50 retention systems. With a pilot diameter of 1.026 inches and a neck diameter of 0.667 inches, the MH500TRKC fits the internal geometry of CAT50 toolholders requiring a Style B knob configuration. It is appropriate for production machining environments where consistent tool pull force and coolant-through capability are required.

Key Features

• CAT50 taper size for use with standard CAT50 toolholders
• 1-8 UNC thread for drawbar engagement on compatible machining centers
• 90-degree angle radius head geometry per Style B specification
• Through-coolant design with 0.25-inch coolant hole diameter
• 0.904-inch knob diameter and 1.026-inch pilot diameter for precise fit
• Compact 0.4-inch flange thickness with 1.78-inch knob-to-flange length

Compatibility

Designed as an OEM-style replacement or spare retention knob for CAT50 toolholders requiring a Style B, 1-8 UNC thread configuration with through-coolant capability.

Installation Notes

Installation should be performed by a qualified machinist or toolroom technician. The machine spindle must be fully powered down and the tool changer disabled before removing or installing retention knobs. Use the correct torque wrench and retention knob socket to achieve proper engagement without damaging threads. Inspect the drawbar and toolholder bore for wear or contamination before reinstalling.