Parlec MH500TRK Retention Knob CAT50 1-8 Thread

Product Description

The PARLEC MH500TRK is a Style B retention knob designed for CAT50 taper toolholders used in CNC machining centers. It threads into the drawbar mechanism of the spindle, securing the toolholder during high-speed cutting operations. The knob features a 1-8 UNC thread, a 90-degree angle radius at the pull stud head, and a knob diameter of 0.904 inches. With an overall length of 3.32 inches and a pilot diameter of 1.026 inches, it is dimensioned for positive seating and repeatable toolholder engagement. Installation and removal are handled by machine tool technicians and CNC setup personnel as part of routine toolholder changes.

This retention knob is suited for CAT50 toolholder assemblies running in horizontal and vertical machining centers that use a 1-8 threaded drawbar pull stud interface. The CAT50 taper is common in heavy-duty production machining environments where larger spindle sizes are required. The 3.32-inch overall length and 1.78-inch knob-to-flange measurement position it within standard CAT50 toolholder body geometry. It is compatible with toolholders requiring a Style B pull stud configuration with a 90-degree angle radius head profile.

Key Features

• CAT50 taper size for use with standard CAT50 toolholder bodies
• 1-8 UNC thread for direct engagement with compatible drawbar mechanisms
• 90-degree angle radius head profile, Style B configuration
• Pilot diameter of 1.026 inches ensures accurate centering in the toolholder bore
• Neck diameter of 0.667 inches and flange thickness of 0.400 inches support proper drawbar pull-out force distribution
• Compact weight of 0.5962 pounds minimizes added mass in the spindle assembly

Compatibility

Designed for CAT50 taper toolholders requiring a Style B retention knob with a 1-8 UNC thread and 90-degree angle radius pull stud interface. Confirm drawbar thread specification and pull stud style with the machine tool manufacturer before installation.

Installation Notes

Installation is performed by a qualified machinist or CNC setup technician. The spindle must be fully powered down and the machine placed in a safe locked-out state before removing or installing retention knobs. Thread the knob into the toolholder by hand first to confirm thread engagement before applying torque with the appropriate spanner or retention knob installation tool. Do not over-torque, as this can distort the toolholder thread or affect drawbar clamping force.