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THE BHP WIRE —
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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Moments that changed communities, movements, institutions and the nation.
In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
A compass saw is a type of saw used for making curved cuts known as compasses, particularly in confined spaces where a larger saw would not fit.[1][2]
Compass saws have a narrow, tapered blade usually ending in a sharp point, typically with a tooth pitch of 2.5 to 3 mm (eight to ten teeth per inch),[2] but down to 1.3 mm (up to 20 teeth per inch) for harder materials and as long as 5 mm (as few as five teeth per inch) for softer materials.[1] They have a curved, light "pistol grip" handle, designed for work in confined spaces and overhead.[2]
The blade of a compass saw may be fixed or retractable, and blades are typically interchangeable. Partially retracting the blade can prevent flexing and breaking when cutting harder materials.[1]
Compass saws are suitable for cutting softer woods, plastic, drywall, and non-ferrous metals.[1][2] The pointed tip of the blade can be used to penetrate softer materials without the need for a pilot hole.[1]
Compared with other saws designed for cutting curves, such as coping or fretsaws, compass saws have a larger blade and longer pitch (fewer teeth per inch). This allows them to cut faster, and to cut through thicker materials, but leaves a rougher finish.[2]
Compared with drywall saws, compass saws typically have a longer blade – at 15 to 30 centimetres (5.9 to 12 in) – and shorter pitch (more teeth per inch).[1][2]
Keyhole saws, also called padsaws or jab saws, feature shorter, finer blades and (often) straight handles, and are suitable for cutting extremely tight curves.[2][3]
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A compass saw is a type of saw used for making curved cuts known as compasses, particularly in confined spaces where a larger saw would not fit.
A keyhole saw (also called a pad saw, alligator saw, jab saw or drywall saw) is a long, narrow saw used for cutting small, often awkward features in various building materials. There are typically two varieties of keyhole saw: the fixed blade type and the retractable blade type. The retractable-blade variety is usually found to have either a cast-iron handle or, less commonly, a wooden handle. The facility to retract the blade to an optimum length serves to prevent unwanted flex to the blade should the full length of the blade be obstructed in some way. In both types, the blade is typically secured by one or two holding/thumb screws. The cheaper, fixed-blade type is more commonly used in the modern construction trade. With the advance of certain building methods and materials, designs specific to these trades have been developed. One such modification being a sharpened point at the tip of the blade which can be pushed or jabbed through soft materials such as drywall without drilling a hole for the blade. Compass saws typically feature a larger, coarser blade, and are designed to cut through tougher materials. Two power tools serving largely the same function but which work more quickly and with less effort are the jigsaw and spiral saw.
A circular saw or buzz saw is a power-saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbor. A hole saw and ring saw also use a rotary motion but are different from a circular saw. Circular saw may also be loosely used for the blade itself. Circular saws were invented in the late 18th century and were in common use in sawmills in the United States by the middle of the 19th century. A circular saw is a tool for cutting many materials such as wood, masonry, plastic, or metal and may be hand-held or mounted to a machine. In woodworking the term circular saw refers specifically to the hand-held type and the table saw and chop saw are other common forms of circular saws. Skilsaw and Skil saw have become generic trademarks for conventional hand-held circular saws in the United States. Circular saw blades are specially designed for each particular material they are intended to cut and in cutting wood are specifically designed for making rip-cuts, cross-cuts, or a combination of both. Circular saws are commonly powered by electricity, but may be powered by a gasoline engine or a hydraulic motor which allows it to be fastened to heavy equipment, eliminating the need for a separate energy source.
In woodworking and carpentry, hand saws, also known as "panel saws", are used to cut pieces of wood into different shapes. This is usually done in order to join the pieces together and carve a wooden object. They operate by having a series of sharp points, called teeth, of a substance that is harder than the wood being cut. Hand saws have been used for thousands of years. Egyptian hieroglyphics exist depicting ancient woodworkers sawing boards into pieces, and ancient bow saws have been found in Japan. Cut patterns on ancient boards are occasionally observed to bear the unique cutting marks left by saw blades, particularly if the wood was not 'smoothed up' by some method. Twenty-four saws from eighteenth-century England are currently preserved. Materials for saw blades have varied over the ages. Bronze saws were likely used before steelmaking technology became extensively known and industrialized. The most popular material for handles of hand saws is applewood; in the early 1900s 2,000,000 board feet of applewood were used annually for this purpose. Sometimes cultures developed two main types of saw teeth: the cross cut saw teeth and the rip saw teeth. These cut into the wood using different mechanisms. Crosscut saws have sawteeth that are shaped, often with a metal file, in such a way that they form a series of tiny knife-like edges. Crosscut saws are meant to cut perpendicular, or against, the wood grain. Rip saws, on the other hand, have chisel-like sawteeth and are meant to cut parallel, or with, the grain. Wood fibers are contacted by the teeth and 'ripped' apart from the bundle of other fibers. It is common that people do not recognize the difference and use saws both ways. However, a rip saw is much faster than a cross-cut saw when cutting with the grain but leaves a very rough cut, often with splinters on the surface, and has more difficulty maintaining a straight cut when cutting across the grain. The cross-cut saw can cut in any direction but is much slower than needs be when cutting with the grain. The development of saws was also affected by several factors. The first was the importance of wood to a society, the development of steel and other saw-making technologies, and the type of power available. These factors were, in turn, influenced by the environment, such as the types of wood or metal available. Finally, the types of jobs the saws were to perform was also important in the development of the technology. Among Basques and Australians, traditional hand sawing has generated rural sports. The Basque variant is called tronral.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
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