Robbjack NR-204-02.5 Square End Mill 5/64 in 2 Flute

Product Description

The ROBBJACK NR-204-02.5 is a solid carbide square end mill from the NR-204 series, designed for precision milling in metalworking and machining applications. It features a 5/64 inch (0.0781 inch) mill diameter with a 1/4 inch length of cut and a 1/8 inch straight cylindrical shank. The 2-flute, right-hand spiral configuration with a 30-degree helix angle promotes efficient chip evacuation in slotting, profiling, and plunge-cutting operations. Centercutting geometry allows direct plunge entry. This tool is uncoated solid carbide grade C2, suited for machinists running close-tolerance work on small-diameter features in ferrous and non-ferrous materials.

This end mill fits residential and commercial machine shop environments, CNC machining centers, and manual knee mills where small-diameter precision cutting is required. The regular length designation and 1-1/2 inch overall length keep deflection low in tight workholding setups. It is a single-end tool intended for finish and semi-finish milling passes on slots, pockets, and contours where dimensional accuracy at sub-1/8 inch diameters is critical. Machinists and toolroom technicians are the primary users.

Key Features

• 5/64 inch mill diameter with mill diameter tolerance of +0.001 / -0.000 inches for consistent close-tolerance cuts
• Solid carbide grade C2 construction for rigidity and wear resistance at small diameters
• 2-flute spiral design with 30-degree helix angle for effective chip removal
• Centercutting geometry permits direct plunge milling without a pre-drilled hole
• Right-hand cut, right-hand flute configuration compatible with standard CNC and manual spindles
• Straight cylindrical shank with shank diameter tolerance of -0.0001 / -0.0002 inches for secure collet retention

Compatibility

Designed as an OEM-style replacement or direct-fit tooling option for standard 1/8 inch collet chucks and ER-style collet systems used on CNC machining centers and manual milling machines requiring small-diameter square end mills.

Installation Notes

Installation should be performed by a qualified machinist or toolroom technician familiar with collet torque procedures and runout verification. Ensure the spindle is fully stopped and locked out before changing tooling. Seat the shank fully into the collet to the recommended engagement depth before torquing the collet nut. Verify runout with a dial indicator before beginning the cut to protect both the tool and the workpiece at this small diameter.