Multiple cut zone blade assembly for a hand operated cutting tool
A hand pruner having a first and second handle, the first handle having a hook, formed at a far end, the second handle having a cutting blade formed at the far end. The first handle and hook and second handle and blade pivotally connected for movement with respect to each other. The blade and second handle having a cup formed between the blade and second handle. The hook and first handle having a cup formed between the hook and first handle. The cutting edge of the hook is formed along two concave intersecting arcs of different diameters, the smaller diameter arc located next to the pivot. The cutting edge of the blade is formed along two convex intersecting arcs having diameters that complement the two concave arcs in the hook cutting edge.
1. A hand operated cutting tool comprising:
a first handle having a near and far end;
a hook at the far end of the first handle, the hook having a tip and a base with a first cutting edge formed along a first concave arc having a fixed continuous radius of curvature extending from the base, and a second cutting edge formed along a second concave arc overlapping the first concave arc and having a larger fixed continuous radius of curvature extending from the tip, the two cutting edges intersecting at a predefined rise point located between the tip and base;
a second handle having a near and far end, the second handle pivotally connected to the first handle for movement with respect to the first handle; and
a cutting blade at the far end of the second handle, the cutting blade having a tip and a base with a first cutting edge formed along a first convex arc having a fixed continuous radius of curvature substantially matching the fixed continuous radius of curvature of the first concave arc on the hook, and a second cutting edge formed along a second convex arc overlapping the first convex arc, having a fixed continuous radius of curvature larger than the fixed continuous radius of curvature of the first convex arc and substantially matching the fixed continuous radius of curvature of the second concave arc on the hook, the two cutting edges intersecting at a predetermined point located between the tip and base and aligned with the predefined rise point on the hook.
2. The hand operated cutting tool of claim 1 further comprising a metal cap at the near end of the first handle, and a metal cap at the near end of the second handle.
3. The hand operated cutting tool of claim 1 further comprising a first cup formed between the first handle and hook and a second cup formed between the second handle and cutting blade, at the pivotal connection between the first handle and second handle.
4. A hand operated cutting tool comprising:
a first handle having a near and far end;
a hook at the far end of the first handle, the hook having a tip and a base with a first cutting edge formed along a first concave arc having a fixed continuous radius of curvature extending from the base, and a second cutting edge formed along a second concave arc overlapping the first concave arc and having a larger fixed continuous radius of curvature extending from the tip, the two cutting edges intersecting at a predefined rise point located between the tip and base;
a second handle having a near and far end, the second handle pivotally connected to the first handle for movement with respect to the first handle; and
a cutting blade at the far end of the second handle, the cutting blade having a tip, a base, and a first and second side, the cutting blade including a first cutting section with a first and second side and a first cutting edge formed along a first convex arc having a fixed continuous radius of curvature substantially matching the fixed continuous radius of curvature of the first concave arc on the hook, and a second cutting section with a second cutting edge formed along a second convex arc overlapping the first convex arc, having a fixed continuous radius of curvature larger than the fixed continuous radius of curvature of the first convex arc and substantially matching the fixed continuous radius of curvature of the second concave arc on the hook,
the two cutting sections intersecting at a predetermined intersection line located between the tip and base and aligned with the predefined rise point on the hook, the first cutting section being ground on the first side to taper from the predetermined intersection line to a portion of the base proximal to the far end of the second handle, and the second cutting section being ground on the first side to taper inwardly from the predetermined intersection line to a tip end at the second cutting section.