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Hammer - china CPR-1000 Current Probe Reader - china CRS-TESTER
History An early stone hammer The use of simple tools dates to about 2,400,000 BCE when various shaped stones were used to strike wood, bone, or other stones to break them apart and shape them.
Stones attached to sticks with strips of leather or animal sinew were being used as hammers by about 30,000 BCE during the middle of the Paleolithic Stone Age. Its archeological record means it is perhaps the oldest human tool known. Designs and variations The essential part of a hammer is the head, a compact solid mass that is able to deliver the blow to the intended target without itself deforming.
The opposite side may have a ball, as in the ball-peen hammer and the cow hammer. Some upholstery hammers have a magnetized appendage, to pick up tacks. In the hatchet the hammer head is secondary to the cutting edge of the tool. As the impact between steel hammer heads and the objects being hit can, and does, create sparks, which in some industries such as underground coal mining with methane gas, or in other hazardous environments containing flammable gases and vapours, can be dangerous and risk igniting the gases. In these environments, a variety of non-sparking metal tools are used, being principally, aluminium or beryllium copper-headed hammers. In recent years the handles have been made of durable plastic or rubber. The hammer varies at the top; some are larger than others giving a larger surface area to hit different sized nails and such. Popular hand-powered variations include: carpenter's hammers (used for nailing), such as the framing hammer and the claw hammer upholstery hammer construction hammers, including the sledgehammer drilling hammer - a lightweight, short handled sledgehammer Ball-peen hammer, or mechanic's hammer Soft-faced hammer cross-peen hammer, or Warrington hammer mallets, including the rubber hammer and dead blow hammer. Splitting maul stonemason's hammer Geologist's hammer or rock pick lump hammer, or club hammer gavel, used by judges and presiding authorities in general Tinner's Hammer Claw hammer Framing hammer Geologist's hammer Upholstery hammer Cross-peen hammer Ball-peen hammer Rubber mallet Wooden mallet Sledgehammer Stone tapping hammer Perforated hammer head of stone Long cross-face hammer (blacksmithing) Twist hammer (blacksmithing) Dog-head hammer (blacksmithing) Ball pane hammer Straight pane sledgehammer Bush hammer Mechanically-powered hammer Mechanically-powered hammers often look quite different from the hand tools, but nevertheless most of them work on the same principle. They include: jackhammer steam hammer trip hammer hammer drill, that combines a jackhammer-like mechanism with a drill In professional framing carpentry, the hammer has almost been completely replaced by the nail gun. In professional upholstery, its chief competitor is the staple gun. Tools used in conjunction with hammers Woodsplitting wedge - hit with a sledgehammer for splitting wood. Woodsplitting maul - can be hit with a sledgehammer for splitting wood. Masonry star drill Chisel Punch Anvil The physics of hammering Hammer as a force amplifier A hammer is basically a force amplifier that works by converting mechanical work into kinetic energy and back. In the swing that precedes each blow, a certain amount of kinetic energy gets stored in the hammer's head, equal to the length D of the swing times the force f produced by the muscles of the arm and by gravity. When the hammer strikes, the head gets stopped by an opposite force coming from the target; which is equal and opposite to the force applied by the head to the target. If the target is a hard and heavy object, or if it is resting on some sort of anvil, the head can travel only a very short distance d before stopping. Since the stopping force F times that distance must be equal to the head's kinetic energy, it follows that F will be much greater than the original driving force f roughly, by a factor D/d.
In this way, great strength is not needed to produce a force strong enough to bend steel, or crack the hardest stone. Effect of the head's mass The amount of energy delivered to the target by the hammer-blow is equivalent to one half the mass of the head times the square of the head's speed at the time of impact (). While the energy delivered to the target increases linearly with mass, it increases geometrically with the speed (see the effect of the handle, below). High tech titanium heads are lighter and allow for longer handles, thus increasing velocity and delivering more energy with less arm fatigue than that of a steel head hammer of the same weight. As hammers must be used in many circumstances, where the position of the person using them cannot be taken for granted, trade-offs are made for the sake of practicality. In areas where one has plenty of room, a long handle with a heavy head (like a sledge hammer) can deliver the maximum amount of energy to the target. It is not practical to use such a large hammer for all tasks, however, and thus the overall design has been modified repeatedly to achieve the optimum utility in a wide variety of situations. Effect of the handle The handle of the hammer helps in several ways. It keeps the user's hands away from the point of impact. It provides a broad area that is better-suited for gripping by the hand. Most importantly, it allows the user to maximize the speed of the head on each blow.
The primary constraint on additional handle length is the lack of space in which to swing the hammer. This is why sledge hammers, largely used in open spaces, can have handles that are much longer than a standard carpenter's hammer. The second most important constraint is more subtle. Even without considering the effects of fatigue, the longer the handle, the harder it is to guide the head of the hammer to its target at full speed. Most designs are a compromise between practicality and energy efficiency. Too long a handle: the hammer is inefficient because it delivers force to the wrong place, off-target. Too short a handle: the hammer is inefficient because it doesn't deliver enough force, requiring more blows to complete a given task. Recently, modifications have also been made with respect to the effect of the hammer on the user.
A titanium head has about 3% recoil and can result in greater efficiency and less fatigue when compared to a steel head with about 27% recoil. Handles made of shock-absorbing materials or varying angles attempt to make it easier for the user to continue to wield this age-old device, even as nail guns and other powered drivers encroach on its traditional field of use. War hammers Main article: War hammer The concept of putting a handle on a weight to make it more convenient to use may well have led to the very first weapons ever invented.[citation needed] The club is basically a variant of a hammer. In the Middle Ages, the war hammer became popular when edged weapons could no longer easily penetrate some forms of armour.[citation needed] Symbolic hammers The hammer, being one of the most used tools by Homo sapiens, has been used very much in symbols and arms. In the Middle Ages it was used often in blacksmith guild logos, as well as in many family symbols. The most recognised symbol with a hammer in it is the Hammer and Sickle, which was the symbol of the former Soviet Union and is very interlinked with Communism/Socialism. The hammer in this symbol represents the industrial working class (and the sickle the agricultural working class). The hammer is used in some coat of arms in (former) socialist countries like East Germany.
In Norse Mythology, Thor, the god of thunder and lightning, wields a hammer named Mjolnir. Many artifacts of decorative hammers have been found, leading modern practitioners of this religion to often wear reproductions as a sign of their faith. References ^ Semaw, S., M. J. Rogers, J. Quade, P. R. Renne, R. F. Butler, M. Domnguez-Rodrigo, D. Stout, W. S. Hart, T. Pickering, and S. W. Simpson. 2003. 2.6-Million-year-old stone tools and associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia. Journal of Human Evolution 45:169-177. ^ 2.5-million-year-old stone tools from Gona, Ethiopia S. Semaw*, P. Renne, J. W. K. Harris*, C. S. Feibel*, R. L. Bernor, N. Fesseha & K. Mowbray* Nature 385, 333-336 (23 January 1997) | doi:10.1038/385333a0; Accepted 25 November 1996 External links Look up hammer in Wiktionary, the free dictionary. Hammer types images and descriptions. The Hammer Museum v d e Types of tools Cutting tools Blade Bolt cutter Broach Ceramic tile cutter Chisel Coping saw Countersink Diamond blade Diamond tool Drill bit Endmill File Fretsaw Froe Glass cutter Grater Hacksaw Hand saw Knife Milling cutter Miter saw Pipecutter Plane Razor Reamer Saw Scalpel Scissors Slasher Surform Switchblade Tap and die Tool bit Utility knife Water jet cutter Wire cutter Wire stripper Garden tools Adze Axe Billhook Bow saw Cultivator Earth auger Edger Garden fork Garden hose Garden trowel Hedge trimmer Hoe Hori hori Irrigation sprinkler Lawn aerator Lawn mower Lawn sweeper Leaf blower Loppers Machete Mattock Pickaxe Pitchfork Plough (plow) Post hole digger Pruning shears (secateurs) Rake Roller Rotary tiller Scythe Sickle Spade Splitting maul String trimmer Hand tools Block plane BNC inserter/remover Brace Bradawl Breaker bar Broom Brush Card scraper Caulking gun Clamp Crimping pliers Crowbar Fish tape Hammer Hawk Hex key Locking pliers Mallet Miter box Nut driver Pipe wrench Pliers Punch Punch down tool Putty knife Ratchet Scratch awl Screwdriver Sledgehammer Sponge Squeegee Staple gun Stitching awl Torque wrench Trowel Upholstery hammer Wrench (spanner) Machine tools Broaching machine Drill press Gear shaper Grinding machine Hobbing machine Jig borer Lathe Metalworking lathe Milling machine Planer Screw machine Shaper Turret lathe Power tools Angle grinder Band saw Belt sander Blow torch Chainsaw Chop saw Circular saw Concrete saw Crusher Cutting torch Die grinder Drill Glue gun Grinding machine Heat gun Impact wrench Jigsaw Jointer Nail gun Radial arm saw Random orbital sander Reciprocating saw Rotary tool Router table Sander Scroll saw Soldering gun Soldering iron Steam box Table saw Thickness planer Welding Wood router Wood shaper Measuring & Alignment tools Caliper Jig Micrometer Pencil Plumb-bob Ruler Sliding T bevel Spirit level Square Tape measure Other Antique tools Halligan bar Kelly tool Ladder Thau claw Toolbox Vise Workbench v d e Metalworking Tools Cutting machines Water jet cutter Band saw Cold saw Laser Miter saw Plasma Cutting tools Broach Burr Chisel Counterbore Countersink End mill File Guillotine shear Hand scraper Milling cutter Nibbler Reamer Throatless shear Tipped tool Tool bit Forming tools Brake Die English Wheel Flypress Hydraulic press Machine press Punch press Stamping press Hand tools Clamp Combination square Drift pin File card Hacksaw Hammer Hand scraper Machinist square Magnetic base Needlegun scaler Pipe and tube bender Pliers Punch Saw piercing Scriber Tap and die Tongs Vise Workbench Wrench Machine tooling Angle plate Chuck Collet Jig Fixture Indexing head Lathe center Machine taper Magnetic base Mandrel Rotary table Wiggler Measuring instruments Bore gauge Caliper Comparator Dial indicator Engineer's blue Feeler Center gauge and fishtail gauge Gauge block Gauge Go-NoGo Machinist square Marking blue Marking gauge Marking out Micrometer Radius gauge Scale Sine bar Spirit level Straightedge Surface plate Tape measure Thread pitch Height gauge Vernier scale Wiggler Smithing tools Anvil Forge Fuller Hardy hole Hardy tools Pritchel Slack tub Steam hammer Swage block Trip hammer Casting Fabrication Forming Jewellery Machining Metallurgy Smithing Tools & Terminology Welding Categories: Hammers | Blunt weapons | Mechanical hand tools | Metalworking hand tools | Woodworking hand tools | Hand toolsHidden categories: Articles needing additional references from December 2009 | All articles needing additional references | All articles with unsourced statements | Articles with unsourced statements from February 2007 | Articles with unsourced statements from May 2008
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