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1 4 Flute 2-1/4 LOR Gorilla Mill Variable Helix Reduced Neck Solid Carbide End Mill

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More Information
Mfg SKU #10620_GMNR10F42_250
end mill categorySquare End
BrandGorilla Mill
Series NameGorilla Mill
cutting diameter1
Shank Diameter1
flute length1-1/8
Length of Reach2-1/4
Overall Length4-1/2
Number of Flutes4
Materialmicrograin carbide
finish coatingGMX-35
helix anglevariable helix
Flute Length TypeReduce Neck Long Reach
Extended ReachYes
Chip Breaker FeatureNo
Single or Double Endsingle
To be used onAlloy Steel, Carbon Steel, Cast Iron, Exotic Material, Hardened Steel, High Temp Alloy, High Temp Nickel Base Alloy, Inconel, Stainless Steel, Titanium
center cuttingYes
end shapeSquare End
Shank Typeround shank
Coolant ThroughNo


Made in USAMade in USA


  • Variable Flute and Index | GMX-35 Coatings

    Patented variable flute and index design which reduces chatter and vibration. Radius corners for stronger edges and part radius.Recommended for aggressive machining applications in all materials including, stainless, inconel, titanium, tool steels and hardened materials. Should be run at specific parameters.Produced with the highest Transverse Rupture Strength (TRS) nano-grain carbide substrate available.

    PATENT NO.7367754

  • Gorilla Mill 4 Flute in Action

    1.0" Diameter 0.750" Axial Engagement
    4140 PH 42.0" IPM
    Profiling 1910 RPM
    0.0250" Radial engagement  
  • GMX-35

    Newly formulated, special high-performance coating for high speed machining. GMX-35 performance surpasses all conventional coatings. This universal high-performance coating is especially designed for milling and drilling. Also suitable for dry machining.

    Structure Nanohardness (GPa) Friction (fretting) Coefficient Thickness (um) Maximum Working Temp. Color
    Gradient 32 0.35 2-4 1100°C (2012°F) Silver Gray


The tool edge preparation process adds strength to the tool cutting edge, lengthens usable tool life, minimizes the propensity of the edge to chip, improves part quality and consistency, and enhances work piece surface finish.

With GMP Edge Prep, we have taken edge preparation to the next level, making it a science. Now the technology and equipment exists to overcome nearly all the current processing problems and to produce a tool that will yield optimum performance in any given operation or application.


Before GMP Edge Prep After GMP Edge Prep

Machining Method

Profiling Full Slotting Pocketing High Velocity


  • Quality Assureance

    Our primary responsibility is to ensure the accuracy and consistency of product being manufactured. We have an array of quality inspection equipment including three Eurotech PG1000’s with up to 145x magnification, a Leica M205 C computerized photo microscope with up to 500x magnification, a Zoller pomSkpGo for edge prep measurements at 100x magnification and two Zoller Genius3 machines which are CNC controlled programmable inspection machines with 50X magnification.

  • Regrinds

    The vast majority of your tooling that Gorilla Mill or anyone else manufactures can be re-sharpened and recoated to “like new” condition on one of our state-of-the-art CNC tool and cutter grinders at a fraction of a new tool’s cost. At Gorilla Mill, our goal is to show cost savings while maintaining a high accuracy rate. Whether it’s Gorilla Mills,® or other variable end mills, standard end mills, Gorilla Drills or any other high performance drills, Gorilla Mill has over 40 years of knowledge and experience to help your bottom line.