Saw
From Free net encyclopedia
- For other uses, see Saw (disambiguation).
Image:Portable sawmill 5882.JPG
A saw is a tool for cutting wood or other material, consisting of a serrated blade (a blade with the cutting edge dentated or toothed) and worked either by hand or by steam, water, electric or other power.
The saw can also be used — or abused — for playing music.
Though Greek mythology indicates Perdix, the nephew of Daedalos, the inventor of the saw, unearthed constructed wooden artifacts from Ancient and Predynastic Egypt suggest possibly a much earlier date (see [1], Predynastic Egypt).
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Saw terminology
- Heel: The end closest to the handle.
- Toe: The end farthest from the handle.
- Front: The side with the teeth (the "bottom edge").
- Back: Opposite the front ("top edge").
- Teeth: Small sharp points along the cutting side of the saw.
- Gullet: Valley between the points of the teeth
- Fleam: The angle of the faces of the teeth relative to a line perpendicular to the face of the saw.
- Rake: The angle of the front face of the tooth relative to a line perpendicular to the length of the saw. Teeth designed to cut with the grain (ripping) are generally steeper than teeth designed to cut across the grain (crosscutting)
- Points per inch (25 mm): The most common measurement of the frequency of teeth on a saw blade. This is measured by setting the tip, or point, of one tooth at the zero point on a ruler, and then counting how many points are contained within one inch (25mm) of length, counting inclusively. There will always be one more point per inch than there are teeth per inch (e.g., a saw with 14 points per inch will have 13 teeth per inch, a saw with 10 points per inch will have 9 teeth per inch). Some saws do not have the same number of teeth per inch throughout their entire length, but the vast majority do.
- Kerf: Width of the saw cut. On most saws the kerf is wider than the saw blade because the teeth are flared out sideways (set). This allows the blade to move through the cut easily without getting stuck (binding). However, some saws are made so that the teeth have no set on one side. This is done so that the saw can lie flat on a surface and cut along the surface without scratching it. These are referred to as flush cutting saws.
Types of saws
There are a number of different categories of saw, all with the same purpose of accurately making larger pieces of wood into smaller pieces of wood. The first and largest division is between hand-powered saws and mechanically powered saws.
Hand saws
Hand-powered saws fall into three divisions, which are defined by the way they hold the blade stiff (a requirement to get an even, clean cut).
A Hand saw uses either simply a blade thick enough to be stiff, or cuts on the pull stoke which reduces the stiffness requirement. This division includes the following specific types of saws:
- Crosscut saw, for making cuts perpendicular to the grain
- Ripsaw, for cutting along the grain
- Hand saw, saws operated by hand as opposed to power saws
- Floorboard saw, with curved blade
- Japanese saw, hand saws that cut on the pull stroke with straight handles
- Keyhole saw or padsaw or compass saw, with narrow pointed blade
- Two-man saw, for cutting large logs
Back saws
The second category of hand saws keep a thinner blade stiff by reinforcing it with a steel or brass back. Back saws are differentiated by length of blade. While this list is not definitive, they are generally named, from longest to shortest: Mitre Saw, Carcase Saw, Tenon saw, and Dovetail saw. These saws also have a handle that is vertical in relation to the blade. A saw with a straight handle that extends from the top back of the blade is referred to as a Gent's saw. Finally, some Dozuki saws, which are an Eastern-style (cut on the pull stroke)saw have backs and are classified as back-saws.
- One type of hand powered Miter saw (makes precisely angled cross cuts) uses a backsaw.
Frame saws
The final category of hand saws stiffens the blade by placing it under tension. This is accomplished by placing the blade in a frame. This division of Frame Saws includes the following types of saws:
- Bow saw, thin blade pulled taut by a twisted cord or rod and nut
- Hacksaw, for cutting metal
- Bucksaw or log saw, for fast, rough cutting
- Coping saw, thin blade tensioned by a metal frame, sometimes called a jigsaw; that term has now become more common to describe a motorized hand held saw with a reciprocating blade.
Mechanically powered saws
Mechanically powered saws mechanically move the teeth past the wood while the saw itself is held stationary. This is accomplished in one of three ways: the teeth are along the perimiter of a flat, circular blade; the blade reciprocates up and down rapidly; or the teeth are along one edge of a continuous band. They are more specifically differentiated as follows:
Circular blade saws
- Circular saw, machine-driven for industrial sawing of log and beams, typically found in sawmills - also name given to smaller hand-held saws
- Table saw, circular blade rises through a slot in a table. It is the most common piece of stationary woodworking equipment. May be direct drive or belt driven; the latter is sometimes called a Contractor's Saw. Can be set on a workbench, on steel legs, or a base specifically built to hold the saw.
- Cabinet saw, similar to a table saw, but more precise and more powerful, often driven by multiple belts - an enclosed base stand is an integral part of the saw
- Radial arm saw, versatile machine used mainly for cross-cutting where the blade is pulled on a guide arm through a piece of wood held stationary on the saw's table
- Rotary saw, for making accurate cuts without the need for a pilot hole in wallboard, plywood, and other thin materials, also called a spiral cut saw or a "RotoZip". The latter is a trademark owned by Bosch Tool Corp. who pioneered this type of saw - design is similar to a small wood router, bits are similar to a twist drill, some cut on the upward twist, some cut downwards
- Electric miter saw, (also called chop saw, cut-off saw or power miter box) – for making accurate cross cuts and miter cuts. The basic model has its circular blade fixed at a 90º angle to the vertical, a compound miter saw's blade can be adjusted to other angles. A sliding compound miter saw has a blade which can be pulled through the work similar to the action of a radial arm saw, which gives a greater capacity for cutting wider workpieces.
Reciprocating blade saws
- Jigsaw, narrow blade for cutting irregular shapes, typically held in one hand. Historically was called a sabre saw (also saber) saw - no longer a common term.
- Reciprocating Saw, action similar to a jigsaw, but much larger, more powerful and with a longer stroke. Normally held in both hands, useful for demolition work. Often called a "Sawzall" which is actually correct only if made by the Milwaukee Tool Co. because they pioneered this type saw and "Sawzall" is their trademark. Reciprocating saw is the correct term to avoid violating trademark rights.
- Scroll saw, motorized version of the coping saw for making intricate curved cuts.
Continuous band
Types of saw blades and the cuts they make
- Crosscut
- In woodworking, a cut made at (or near) a right angle to the direction of the grain of the workpiece. A crosscut saw is used to make this type of cut.
- Rip cut
- In woodworking, a cut made parallel to the direction of the grain of the workpiece. A rip saw is used to make this type of cut.
- Plytooth
- A circular saw blade with many small teeth designed for cutting plywood with minimal splintering
- Dado blade
- A special type of circular saw blade used for making grooved cuts in wood so the edge of another piece of wood will fit into the groove to make a joint. Dado blades can make different width grooves by addition of chipper blades of various widths between the outer dado blades.
See also
da:Sav de:Säge es:Sierra (herramienta) fr:Scie io:Segilo it:Sega (strumento) nl:Zaag ja:鋸 no:Sag nn:Sag pl:Piła (narzędzie) ru:Пила simple:Saw fi:Saha sv:Såg