Robbjack NR-404-08 Square End Mill 1/4 in 4 Flute Solid Carbide

Product Description

The ROBBJACK NR-404-08 is a solid carbide square end mill designed for precision milling in metalworking and machining applications. Built to Series NR-404 standards, it features a 0.25 inch cutting diameter, a 0.75 inch length of cut, and a 2.5 inch overall length. The four-flute, right-hand spiral configuration promotes efficient chip evacuation and a smooth cutting action. Carbide grade C2 construction provides the hardness and wear resistance needed for consistent performance in ferrous and non-ferrous materials. Centercutting geometry allows the tool to plunge directly into the workpiece, expanding its range of use in slotting, profiling, and pocket milling operations.

This end mill is suited for use on CNC machining centers and manual mills in production and job-shop environments. The regular length profile and straight cylindrical shank make it a straightforward fit in standard collet chucks and end mill holders with a 0.25 inch bore. Uncoated carbide at grade C2 is a common choice when machining aluminum, brass, and mild steels where coating buildup or heat sensitivity is a concern. The 30-degree helix angle balances cutting efficiency with edge stability across a range of cutting depths and feed rates.

Key Features

• Solid carbide C2 grade construction for hardness and wear resistance
• Four right-hand spiral flutes with centercutting capability for plunge entry
• 0.25 inch cutting diameter with a mill diameter tolerance of +0.001 / -0.000 inches
• 0.75 inch length of cut suits standard slotting and profiling depths
• 30-degree helix angle balances chip flow and edge stability
• Straight cylindrical shank with tight tolerance of -0.0001 / -0.0002 inches for secure tool holding
• Uncoated finish appropriate for non-ferrous and mild ferrous materials

Compatibility

Designed as an OEM-style replacement and standard cutting tool for use in 0.25 inch bore collet chucks, ER collet systems, and end mill holders on CNC machining centers and conventional milling machines.

Installation Notes

Installation should be performed by a qualified machinist or CNC setup technician. Ensure the spindle is fully stopped and the machine is in a safe, locked-out state before changing tooling. Seat the shank fully into the holder and torque the collet nut or set screw to the tool holder manufacturer specifications. Verify runout with a dial indicator before beginning a cut to protect both the tool and the workpiece.