Kennametal 1026729 Retention Knob BT40 5/8-11 Thread

Product Description

The KENNAMETAL 1026729 is a retention knob designed for BT40 taper toolholders used in CNC machining centers. It threads into the drawbar mechanism of the spindle to secure the toolholder during cutting operations. The knob features a 5/8-11 thread size, a 45-degree angle radius at the flange contact, and a knob diameter of 0.589 inches. Overall length is 2.25 inches. This hardware is installed by CNC machine operators, tool crib technicians, and maintenance machinists performing toolholder setup or replacement on BT40-spindle machines.

This retention knob is suited for use in vertical and horizontal machining centers equipped with BT40 spindle tapers. It is a direct replacement component installed when a knob shows wear, cross-threading, or fails torque inspection. The neck diameter measures 0.392 inches, the pilot diameter is 0.636 inches, and the knob-to-flange length is 1.264 inches. No through-coolant feature is present on this knob, making it appropriate for dry or flood-coolant toolholder configurations that route coolant externally.

Key Features

• BT40 taper specification for compatibility with BT40 spindle drawbar systems
• 5/8-11 thread size for secure engagement with standard BT40 drawbar pull studs
• 45-degree angle radius at flange contact for proper seating and pull force distribution
• 0.636-inch pilot diameter provides positive centering within the toolholder bore
• Compact 2.25-inch overall length suits standard BT40 toolholder geometry
• No through-coolant port - suited for external coolant delivery setups

Compatibility

Designed as an OEM-style replacement retention knob for BT40 taper toolholders using a 5/8-11 thread drawbar interface.

Installation Notes

Retention knobs are installed by machinists or tool crib personnel. Always remove the toolholder from the spindle and ensure the machine is locked out and the spindle is fully de-energized before replacing a retention knob. Use the manufacturer-recommended torque procedure for BT40 pull studs - do not over-torque, as this can deform the knob or damage the toolholder bore. Inspect the mating drawbar threads for wear or damage before installing a new knob.