Saw Sharpening California Ajax Solutions Team（看到磨加州Ajax解决方案团队）.pdfVIP

Saw Sharpening Ken Greenberg September 23, 2004 Theory Points The coarseness and fineness of saw teeth are conventionally measured by points – this is the number of teeth in an inch, and is the number you will find stamped into the heel of many saw blades. Note that points are not the same as Teeth Per Inch, which should always be one less. Consider this diagram: Logically, if the first tooth of the inch belongs to this inch, then the last tooth belongs to the next inch – thus the number will be one smaller. Just use points, as they are the more conventional terminology. Tooth Shapes The shape of a saw tooth reflects its intended purpose. There are many specialty saws, which are outside the scope of this discussion, so we can focus only on the rip and crosscut as the two most common ways of shaping the teeth of saws. These cover the majority of “hand” saws (the term sometimes applied to saws without backs) and saws with reinforced backs due to the thin blades in use. Consider the needs of sawing through a structure like the traditional “bundle of soda straws.” Almost any shape can be used to cut parallel to the tubes, and a chisel works about as well as anything else. It has the advantage of being simple to form. However, a chisel shape is less efficient in cutting across the tubes, where a knife shape that can slice through the tube requires considerably less effort. For this reason, the cross cut is considered more general purpose. The panel saw (a backless hand saw about 20 inches long and designed to fit in a portable toolbox) is always filed crosscut, based on the idea that if you are only going to have one saw with you, this is the tooth shape you want. Why a rip saw at all, then? The theory is that a coarse cut made with a chisel shape (and probably fewer teeth per inch) is faster, and you’re going to plane the resulting surface anyway. Thus, you want to go fast and not care so much about smoothness of cut, and the rip saw meets these