Accupro 771038 CAT40 End Mill Holder 5/8 Inch Bore

Product Description

The ACCUPRO 771038 is a CAT40 dual contact taper shank end mill holder designed for CNC machining centers requiring high-speed, high-precision tool holding. It accepts a 5/8 inch bore and delivers a 5.5 inch projection from the spindle face, with a 1-21/32 inch nose diameter. Through-coolant capability supports both through-spindle and DIN flange coolant delivery, making it suited for deep-cavity milling, extended-reach operations, and applications where chip evacuation and tool cooling are critical. The dual contact taper interface engages both the taper and the spindle face simultaneously, improving rigidity and repeatability over standard single-contact CAT40 holders. Licensed machinists and CNC setup technicians are the primary installers.

This end mill holder is used in production and job-shop CNC vertical and horizontal machining centers equipped with CAT40 dual contact spindles. It is appropriate for high-speed machining operations where runout control is essential. The 30,000 RPM balance rating makes it a practical choice for high-spindle-speed finishing passes as well as general roughing applications in steel, aluminum, and similar materials. The 5/8-11 retention knob thread size is a standard CAT40 specification that accommodates widely available retention hardware.

Key Features

• CAT40 dual contact taper shank engages both taper and spindle face for increased rigidity and reduced deflection
• 5/8 inch bore diameter accommodates standard end mills and cutting tools
• 5.5 inch projection provides extended reach for deep-cavity and stepped-workpiece setups
• Through-coolant compatible with both through-spindle and DIN flange delivery systems
• TIR of 0.0002 inch supports tight-tolerance finishing operations
• Balanced to 30,000 RPM for safe use on high-speed spindles

Compatibility

Designed for CNC machining centers with CAT40 dual contact spindle interfaces. Retention knob thread size is 5/8-11. No specific machine model compatibility was stated in the product data.

Installation Notes

Installation should be performed by a qualified CNC machinist or setup technician. Power down and lock out the machine spindle before mounting or removing any tool holder. Inspect the spindle taper and holder taper for nicks, debris, or wear before seating; contamination on dual contact surfaces directly affects clamping accuracy and runout. Torque the retention knob according to the machine tool builder specifications for CAT40 tooling — do not use an arbitrary value.