circular saw

The circular saw is a metal disc or blade with saw teeth on the edge as well as the machine that causes the disk to spin. It is a tool for cutting wood or other materials and may be hand-held or table-mounted. While today they are almost exclusively powered by electricity, larger ones, such as those in "saw mills", were traditionally powered by water turning a large wheel. Most of these saws are designed to cut wood but may be equipped with blades designed to cut masonry, plastics or metal although there are purpose-made circular saws specially designed for particular materials.

Invention

Various claims have been made as to who invented the circular saw:

• One suggestion is that it was invented in 1813 by Tabitha Babbit, a Shaker spinster, who sought to ease the labour of the male sawyers in her community.^[1]
• Another frequent claim is for a little known sailmaker named Samuel Miller of Southampton, England who obtained a patent in 1777 for a saw windmill.^[2] However the specification for this only mentions the form of the saw incidentally, probably indicating that it was not his invention.
• Walter Taylor of Southampton had the blockmaking contract for Portsmouth Dockyard. In about 1762 he built a saw mill where he roughed out the blocks. This was replaced by another mill in 1781. Descriptions of his machinery there in the 1790s show that he had circular saws. Taylor patented two other improvements to blockmaking but not the circular saw.^[3] This may suggests that he did not invent it.
• Another claim is that it originated in Holland in the sixteenth or seventeenth century.^[4] This may be correct, but nothing more precise is known.

Types of circular saw

In addition to hand-held circular saws (see below), different saws that use circular saw blades include:

• Miter saws (or Chop saw or Cut-off saw)
• Radial arm saws
• Saw mills
• Table saws
• Panel saws
• Biscuit joiners
• Pendulum saw
• Brushcutter

Sawmill blades

Saw mills use very large circular saws, up to nine feet (2.97 meters) in diameter. They are either left or right handed, depending on which side of the blade the plank falls away from. Benching determines which hand the saw is. Saws of this size typically have a shear pin hole, off axis, that breaks if the saw is overloaded and allows the saw to spin free. The most common version is the ITCO (insert tooth cut-off) which has replaceable teeth. Sawmill blades are also used as an alternative to a radial arm saw.

Cordwood Saws

Cordwood saws, also called buzz saws in some locales, use blade of a similar size to sawmills. Where a sawmill rips (cuts with the grain) a cordwood saw crosscuts (cuts across the grain). Cordwood saws can have a blade from 20 to more than 36 inches diameter depending on the power source and intended purpose. Buzz saws are used to cut long logs (cordwood) and slabs (sawmill waste) into pieces suitable for home heating (firewood).

Most cordwood saws consist of a frame, blade, mandrel, cradle, and power source. The cradle is a tilting or sliding guide that holds logs during the cutting process. Some cordwood saws are run from a belt from a farm tractor power takeoff pulley. Others are equipped with small gasoline engines or even large electric motors as power sources. The mandrel is a shaft and set of bearings that support and transfer power to the blade. The frame is a structure that supports the cradle and blade at a convenient working height.

Cordwood saws were once very popular in rural America. They were used to cut smaller wood into firewood in an era when hand powered saws were the only other option. Logs too large for a cordwood saw were still cut by hand. Chainsaws have largely replaced cordwood saws for firewood preparation today. Still, some commercial firewood processors and others use cordwood saws to save wear and tear on their chainsaws. Most people consider cordwood saws unsafe and outdated technology.

See also

• Diamond Blade
• Diamond tools
• Cold Metal Cutting Saw

External links

• History of the portable circular saw
• Hand held power saws Has a section on handling kickback.
• Circular Saw Safety Procedures

References

1. ^ John O. Curtis, 'The Introduction of the Circular Saw in the Early 19th Century' Bulletin of the Association for Preservation Technology Vol. 5, No. 2 (1973), pp. 162-189; also Inventors website and Wood News
2. ^ English Patent Specification no. 1152 (1777); and see Inventors website
3. ^ Carolyn C. Cooper, 'The Portsmouth System of Manufacture' Technology and Culture 25(2) (1984), 182-195; C. Singer et al., History of Technology IV (1958), 437; Norman Ball, 'Circular Saws and the History of Technology' Bulletin of the Association for Preservation Technology Vol. 7, No. 3. (1975), pp. 79-89.
4. ^ Ball, 'Circular Saws' quoting M. Powis Bale, Woodworking Machinery. Its Rise, Progress and Construction.

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