Abstract: Tools, including end mills, include a flute having a helix which varies along the length of the tool. The invention is not limited in terms of the number of flutes, whether odd or even; helix change(s) within a flute or between flutes; or indexing between cutting edges or flutes. Nor is the invention limited in terms of materials used, and may employ carbide or high-speed steel grades of materials, ceramics, or any other material that will be used in the future for material removal in a rotary tool. According to the invention, a ‘slow’ or ‘high’ helix may be used at the end or starting point of the tool, depending upon the application. A slow helix at the end or starting point is desirable for a strong corner in ramping and plunging into the material. When a higher helix is used at the end transitioning to a smaller helix at the shank, the corner is also protected because of the helix change. The high helix at the tip may be needed for shearing action in a given material.

Abstract: Tools, including end mills, include a flute having a helix which varies along the length of the tool. The invention is not limited in terms of the number of flutes, whether odd or even; helix change(s) within a flute or between flutes; or indexing between cutting edges or flutes. Nor is the invention limited in terms of materials used, and may employ carbide or high-speed steel grades of materials, ceramics, or any other material that will be used in the future for material removal in a rotary tool. According to the invention, a ‘slow’ or ‘high’ helix may be used at the end or starting point of the tool, depending upon the application. A slow helix at the end or starting point is desirable for a strong corner in ramping and plunging into the material. When a higher helix is used at the end transitioning to a smaller helix at the shank, the corner is also protected because of the helix change. The high helix at the tip may be needed for shearing action in a given material.

Abstract: In a cutting tool such as an end mill, router bit, tap, thread mill, or other form of insertable rotary tooling, the edge from the center of the tool to the cutting diameter is not a straight line, but instead assumes an arcuate shape. This increases the clearance associated with the center of the tool. In one disclosed example, an arc-ended, ½-inch diameter tool according to the invention starting with a 4-degree dish angle but transitioning to a larger angle of 8 degrees results in a clearance of 0.35, an amount double to the straight-line cut of at 4 degrees, which results in a clearance of 0.0175 drop at center. Broadly, any change in dish angle from lower to higher to increase clearance is anticipated by the invention, including zero degrees to 10 degrees of more, and so forth.