Parlec 4004TRK Retention Knob BT40 M16 X 2.00 Thread

Product Description

The PARLEC 4004TRK is a Style C retention knob designed for BT40 taper toolholders used in CNC machining centers. The knob secures the toolholder in the machine spindle by engaging the drawbar mechanism, providing the clamping force necessary for accurate, repeatable tool engagement. Key dimensions include a 0.588-inch knob diameter, a 2.36-inch overall length, and an M16 x 2.00 thread size. The 60-degree angle radius geometry at the knob head is consistent with standard BT toolholder drawbar engagement requirements. Licensed machinists and CNC setup technicians install this component during toolholder assembly or when replacing a worn or damaged retention knob.

This retention knob fits BT40 taper toolholders and is appropriate for use in vertical and horizontal CNC machining centers equipped with BT40 spindles. The 0.669-inch pilot diameter and 0.393-inch neck diameter are sized for proper seating and alignment within compatible BT40 holders. With a 1.376-inch knob-to-flange length and a 0.23-inch flange thickness, the 4004TRK meets the dimensional requirements for correct drawbar pull engagement in standard BT40 spindle configurations. Through-coolant is not supported by this knob.

Key Features

• BT40 taper specification for compatibility with BT40 spindle toolholders
• M16 x 2.00 thread size for engagement with standard BT40 drawbar mechanisms
• 60-degree angle radius geometry for proper drawbar seating and clamping force distribution
• Style C knob profile with 0.588-inch knob diameter and 0.669-inch pilot diameter
• Compact 2.36-inch overall length with 0.23-inch flange thickness for precise fitment
• No through-coolant passage - solid construction for standard dry or flood-coolant applications

Compatibility

Designed as an OEM-style replacement retention knob for BT40 taper toolholders requiring an M16 x 2.00 thread and Style C knob geometry.

Installation Notes

Retention knobs are installed and torqued by machinists or CNC toolroom technicians during toolholder assembly. Always remove the toolholder from the spindle and de-energize the machine before servicing retention hardware. Use the appropriate spanner or retention knob installation tool to achieve proper seating - do not use impact tools, and do not over-torque, as this can distort the toolholder taper. Inspect the drawbar and spindle threads for wear or contamination before installing a new retention knob.