Handsaw with Pressure_Controlled handle

Abstract

The principles of our invention can be applied to both push-saws and pull-saws. More points could, of course, be used. A change in the pitch changes the ratio between forces applied parallel and perpendicular to the stroke direction, and therefore determines how aggressive the saw will behave. For hard stock, a less aggressive behavior is more efficient, decreasing the forces applied perpendicular to the stroke direction. For soft stock, a more aggressive behavior is more efficient, increasing the forces applied perpendicular to the stroke direction and decreasing the number of strokes necessary to cut through a particular piece of stock. Furthermore, the preferred embodiment of our invention allows multiple saw blades to be used with each saw for cutting a variety of materials (wood, metal, plastics, etc.).

Description

Many kinds of handsaws are available on the market today. Most of the design variations have to do with blade or handle type to best fit a particular type of job. A wood saw might have relatively coarse teeth, and can cut soft and hard woods. However, a single wood saw blade cannot be optimized to cut both hard and soft stock. If it cuts hard stock well, it will tend to cut soft stock slowly. If it cuts stock well, it will tend to cut hard stock with difficulty.

Our invention allows optimization of applied pressure to the stock being cut with a simple adjustment of pitch between the handle and blade of the saw.

Two directional forces are necessary in using a handsaw. One force is oriented parallel to the stroke of the saw to move the teeth through the stock. The other force is oriented perpendicular to the stroke of the saw to push the teeth into engagement with the stock with each successive stroke.

The line (or curve) of the teeth on a handsaw determines the direction of the stroke for the saw. The pitch on the handle governs the ratio of pressure devoted to parallel force versus perpendicular force. For typical handsaw designs, the pitch on the handle is fixed relative to the stroke direction because the handle is fixedly mounted to the blade. Our handsaw design allows the handle pitch to be changed to optimize cutting of softer or harder stocks, thus improving saw performance for a wider range of applications. The degree of pitch is indicated in our preferred embodiment with “Heavy” indicating high relative perpendicular force applied and “light” indicating low relative perpendicular force applied. Variations in terminology could, of course, be used.

Claims

1. The preferred embodiment of this invention allows the handle pitch to be adjusted without the need for tools.

2. As claimed in claim 1, the handle has a pivot point, about which it can be rotated to two or three preset points to change the pitch (see enclosed drawings).