Accupro 88.601.40.AP BT40 Retention Knob High Torque Style C

Product Description

The ACCUPRO 88.601.40.AP is a BT40 retention knob designed to secure tool holders in BT40 spindle tapers on CNC machining centers. It features a 45-degree angle radius and a high-torque design, making it suitable for demanding cutting applications where secure tool clamping is critical. The knob measures 0.5905 inches in knob diameter, 2.3622 inches in overall length, and weighs 0.25 pounds. Style C geometry provides consistent pull-stud engagement across compatible BT40 spindle systems. Installation is performed by CNC machinists and toolroom technicians during tool holder assembly and changeover.

This retention knob is used in CNC milling and machining center applications that utilize BT40 taper spindles. It is suited for both production and job-shop environments where reliable tool holder retention is required. The M16x2 threaded interface engages the drawbar mechanism inside the spindle, and the through-coolant feature is not present on this model, making it appropriate for dry or external coolant setups. Flange thickness is 1.1024 inches with a knob-to-flange length of 1.3779 inches.

Key Features

• BT40 taper size for compatibility with standard BT40 spindle systems
• High-torque design for secure clamping under heavy cutting loads
• 45-degree angle radius pull-stud geometry, Style C
• M16x2 thread size for drawbar engagement
• No through-coolant passage — suitable for external coolant applications
• Compact neck diameter of 0.3937 inches for clearance in tight spindle interfaces

Compatibility

Designed for use with BT40 taper tool holders and CNC machining center spindles that accept a Style C, M16x2 retention knob with a 45-degree angle radius pull-stud.

Installation Notes

Retention knobs are installed by CNC machinists or toolroom personnel using the appropriate spanner wrench or retention knob installation tool. The spindle must be powered down and the drawbar disengaged before removing or installing any retention knob. Follow the tool holder manufacturer torque guidelines and applicable shop safety procedures. Do not over-torque the retention knob, as this can distort the tool holder taper and degrade spindle accuracy.