drill, tool used to create a hole, usually in some hard substance, by its rotary or hammering action. Many different tools make up the drill family. The awl is a pointed instrument used for piercing small holes. In its early form it was a thorn or a tool of bone or chipped flint; many prehistoric awls of flint have been found. The gimlet, which consists of a cross handle holding a metal shaft with a screw point, is used for boring small holes. Its principle and that of a similar tool, the auger, were known and used in ancient times, but the tools were much improved in the Middle Ages. The auger has a cross handle containing a shaft that usually ends with a central screw-shaped point; the point acts to pull two knife edges about it into the material to do the actual cutting. Spiral channels extend part way up the shaft to allow chips to be removed from the hole. The term auger is also applied to various augerlike tools. More elaborate types of drills are composed of two main parts: a replaceable device that does the actual cutting, called a bit, and a second device that drives it. Both devices may be referred to as drills. Two common types of rotary bits are the auger and the twist bit. Hand-powered rotary driving devices include the hand drill, which has a crank that transmits turning power to the bit through a gear and pinion, and the bit brace, which is a bow-shaped device that is rotated to turn a bit. Motor-powered rotary driving devices include the drill press and the portable electric drill, both used at home or in industry for cutting holes in such materials as metal, wood, and plastic. The core drill cuts an annular hole through minerals. For a small hole the drill bit may contain diamonds, which bore a hole by their abrasive action when they are rotated. A rotary oil well drill uses a bit containing either rolling cutters with hard teeth or a fixed, chisel cutting edge. The percussive types of drill force a bit to move forward by a hammering action that chips away material, instead of cutting or abrading it. For example, an air percussion drill chips through rock with a cross-shaped bit driven by a piston; the similar churn drill is lifted and dropped by cable. One special kind of drill, the fusion drill, creates a hole by melting or flaking minerals with an oxyacetylene torch. An agricultural implement for planting certain seeds or for placing fertilizer in the soil is called a drill. Small drills for gardens are pushed by hand; large drills for field work are drawn by horses or tractors. The agricultural drill is named for its special uses, e.g., the grass drill and the grain drill, or for its construction, as the disk drill and the hoe drill. The fertilizer drill is commonly combined with the seed drill.
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A metal or wood member used to stiffen or support a structure; a strut that supports or fixes another member in position, or a tie used for the same purpose.
Supporting member across the corner of a rectangular frame or structure.
A subordinate diagonal brace, crossing the main brace of a truss, which resists variable live loads and helps to dampen any vibration.
A pair of braces crossing each other to stabilize a structural frame against lateral force
A system of inclined members for bracing the angles between the members of a structural frame against horizontal forces, such as wind.
A diagonal corner member for bracing the angle between two joined members; being joined to each other partway along its path serves to stiffen and strengthen the joint.
Stabilizing a wall beam or structural system against lateral forces by means of diagonal or cross bracing either horizontally by roof or floor construction or vertically by pilasters, columns or cross walls.
A diagonal member designed to resist wind loads or other horizontal forces acting on a light structural frame.
A truss panel, or similar structure, with a pair of diagonal braces from corner to corner that form a crossed shape; may be either struts in compression or tie rods in tension.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
(in structural engineering), a connecting element that ensures the stability of a main (supporting) member of the frame and contributes to the three-dimensional rigidity of the structure as a whole. Loads applied to one or more structural members are redistributed by means of braces to the adjacent members and the whole structure. A bracing system usually consists of rod systems—such as trusses and portals—and individual rods—for example, angle braces and cross braces. Braces are used most often in steel and wood structures.
A system of horizontal (in the top and bottom chords of the truss) and vertical bracing is used in the roofs of industrial and public buildings whose supporting members are in the form of plane trusses or latticed collar beams, which can bend out of the plane of the supporting members. Such a system of braces is usually used to tie together two supporting roof members: a three-dimensional assembly is formed that has sufficient rigidity with respect to bending in the horizontal plane and with respect to twisting. The other supporting members of the roof are connected to this assembly by means of purlins, cross braces, or ties. Vertical bracing is also installed along columns (usually in the form of latticed portals and spreaders) to prevent the cross frame of a building from bending out of its plane and to guard against the absorption of the longitudinal loads that arise from wind action or the braking of bridge cranes—for example, in one-story industrial buildings with steel or reinforced-concrete frames. In multistory frame buildings, continuous reinforced concrete cores are often used instead of vertical braces along columns (seeFRAME-PANEL MEMBERS).
The principle of forming a rigid three-dimensional assembly from plane supporting members by means of appropriate bracing systems is also made use of in bridges and tower-type structures.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
A cranklike device used for turning a bit.
A diagonally placed structural member that withstands tension and compression, and often stiffens a structure against wind.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. A metal or wood member which is used to stiffen or support a structure; a strut which supports or fixes another member in position or a tie used for the same purpose.
A tool having a handle, crank, and chuck; used for holding a bit or auger and rotating it to drill a hole by hand; also called a bit stock
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
1. a hand tool for drilling holes, with a socket to hold the drill at one end and a cranked handle by which the tool can be turned
2. a sliding loop, usually of leather, attached to the cords of a drum: used to change its tension
3. a line or bracket connecting two or more staves of music
4. an appliance of metal bands and wires that can be tightened to maintain steady pressure on the teeth for correcting uneven alignment
5. Med any of various appliances for supporting the trunk, a limb, or teeth
7. (in square-rigged sailing ships) a rope that controls the movement of a yard and thus the position of a sail
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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