Electric motor brake

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An electric motor brake (commonly referred to as an electric brake) is a safety feature incorporated into many modern power tools, such as circular saws, drills, and miter saws. Many manufacturers implement this feature into tools specifically with a spinning blade or cutter.

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Usage in corded tools

An electric brake is commonly used in corded tools such as circular saws, miter saws, routers, bandsaws, angle grinders, and more recently, table saws. These mechanisms are designed to prevent injuries resulting from things like kickback or skin-to-blade contact. The way these mechanisms work are almost universally the same; when the trigger or switch is released, the polarity of the electricity running to the motor's brushes is reversed, which decelerates the motor to a stop much quicker than it otherwise would. In circular saws, this feature can reduce the risk of the saw jolting backwards when the saw is set down, as well as prevent damage to the cord or the user. In other tools (such as miter saws or table saws), the brake can reduce the risk of injury to an operator's fingers or hands when the saw is switched off (such as when grabbing a scrap piece off the table). The disadvantage of this feature is that it wears the brushes prematurely when compared to non-brake tools. The first use of an electric brake on a tool was that of the miter saw, invented in 1964 by Ed Niehaus, a tool engineer for Rockwell Tools. Since then, a number of manufacturers have incorporated brakes into their power tools.

Usage in cordless tools

Electric brakes on cordless tools have been prevalent since the invention of the first cordless drill by Makita in 1969. They are found on most cordless tools, with the exception of cordless vacuums and blowers, etc., where such a feature offers no benefit. The way the brake on cordless tools works is slightly different than in corded models; when the switch is released, the motor terminals are shorted together, causing the motor to stop almost instantly by dissipating the rotational energy in the windings. This method is practical for the small permanent-magnet motors in cordless tools, which have low inertia, and is applicable to both brushed and brushless variants. This would not work on corded tools, as they generally use wound field magnets instead of permanent magnets.

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Circular saw Power tool

A circular 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 saws 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 power tool is a tool that is actuated by an additional power source and mechanism other than the solely manual labor used with hand tools. The most common types of power tools use electric motors. Internal combustion engines and compressed air are also commonly used. Other power sources include steam engines, direct burning of fuels and propellants, such as in powder-actuated tools, or even natural power sources such as wind or moving water. Tools directly driven by animal power are not generally considered power tools.

Drill Tool used to create holes

A drill is a tool primarily used for making round holes or driving fasteners. It is fitted with a bit, either a drill or driver, depending on application, secured by a chuck. Some powered drills also include a hammer function.

Chainsaw Portable handheld powered cutting tool

A chainsaw is a portable gasoline-, electric-, or battery-powered saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. It is used in activities such as tree felling, limbing, bucking, pruning, cutting firebreaks in wildland fire suppression, and harvesting of firewood. Chainsaws with specially designed bar-and-chain combinations have been developed as tools for use in chainsaw art and chainsaw mills. Specialized chainsaws are used for cutting concrete during construction developments. Chainsaws are sometimes used for cutting ice; for example, ice sculpture and winter swimming in Finland.

Table saw Woodworking tool

A table saw is a woodworking tool, consisting of a circular saw blade, mounted on an arbor, that is driven by an electric motor. The blade protrudes through the top of a table, which provides support for the material, usually wood, being cut.

Lawn mower Grass cutting device

A lawn mower is a machine utilizing one or more revolving blades to cut a grass surface to an even height. The height of the cut grass may be fixed by the design of the mower, but generally is adjustable by the operator, typically by a single master lever, or by a lever or nut and bolt on each of the machine's wheels. The blades may be powered by manual force, with wheels mechanically connected to the cutting blades so that when the mower is pushed forward, the blades spin or the machine may have a battery-powered or plug-in electric motor. The most common self-contained power source for lawn mowers is a small internal combustion engine. Smaller mowers often lack any form of propulsion, requiring human power to move over a surface; "walk-behind" mowers are self-propelled, requiring a human only to walk behind and guide them. Larger lawn mowers are usually either self-propelled "walk-behind" types or more often, are "ride-on" mowers, equipped so the operator can ride on the mower and control it. A robotic lawn mower is designed to operate either entirely on its own or less commonly by an operator by remote control.

String trimmer Garden tool for trimming grass or groundcover with a flexible line instead of a blade

A string trimmer, also called a weed eater, weed whacker, weedwacker, weed whip, line trimmer, brush cutter, whipper snipper or strimmer, is a garden tool for cutting grass, small weeds, and groundcover. It uses a whirling monofilament line instead of a blade, which protrudes from a rotating spindle at the end of a long shaft topped by a gasoline engine or electric motor.

Brushless DC electric motor Synchronous electric motor powered by an inverter

A brushless DC electric motor, also known as an electronically commutated motor or synchronous DC motor, is a synchronous motor using a direct current (DC) electric power supply. It uses an electronic closed loop controller to switch DC currents to the motor windings producing magnetic fields which effectively rotate in space and which the permanent magnet rotor follows. The controller adjusts the phase and amplitude of the DC current pulses to control the speed and torque of the motor. This control system is an alternative to the mechanical commutator (brushes) used in many conventional electric motors.

DC motor

A DC motor is any of a class of rotary electrical motors that converts direct current electrical energy into mechanical energy. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor.

Kill switch Safety mechanism to quickly shut down a system

A kill switch, also known as an emergency stop (E-stop), emergency off (EMO) and as an emergency power off (EPO), is a safety mechanism used to shut off machinery in an emergency, when it cannot be shut down in the usual manner. Unlike a normal shut-down switch or shut-down procedure, which shuts down all systems in order and turns off the machine without damage, a kill switch is designed and configured to abort the operation as quickly as possible and to be operated simply and quickly. Kill switches are usually designed to be noticeable, even to an untrained operator or a bystander.

Bandsaw

A bandsaw is a power saw with a long, sharp blade consisting of a continuous band of toothed metal stretched between two or more wheels to cut material. They are used principally in woodworking, metalworking, and lumbering, but may cut a variety of materials. Advantages include uniform cutting action as a result of an evenly distributed tooth load, and the ability to cut irregular or curved shapes like a jigsaw. The minimum radius of a curve is determined by the width of the band and its kerf. Most bandsaws have two wheels rotating in the same plane, one of which is powered, although some may have three or four to distribute the load. The blade itself can come in a variety of sizes and tooth pitches, which enables the machine to be highly versatile and able to cut a wide variety of materials including wood, metal and plastic.

Dremel is a multinational brand of power tools, focusing on home improvement and hobby applications. Dremel is known primarily for its rotary tools such as the Dremel 3000, 4000 and 8200 series which are similar to the pneumatic die grinders used in the metalworking industry by tool or moldmakers. Dremel later expanded its product range and now produces butane tools, benchtop and hand-held saws and oscillating tools.

Miter saw

A miter saw or mitre saw is a saw used to make accurate crosscuts and miters in a workpiece by positioning a mounted blade onto a board. A miter saw in its earliest form was composed of a back saw in a miter box, but in modern implementation consists of a powered circular saw that can be positioned at a variety of angles and lowered onto a board positioned against a backstop called the fence.

Universal motor

The universal motor is a type of electric motor that can operate on either AC or DC power and uses an electromagnet as its stator to create its magnetic field. It is a commutated series-wound motor where the stator's field coils are connected in series with the rotor windings through a commutator. It is often referred to as an AC series motor. The universal motor is very similar to a DC series motor in construction, but is modified slightly to allow the motor to operate properly on AC power. This type of electric motor can operate well on AC because the current in both the field coils and the armature will alternate synchronously with the supply. Hence the resulting mechanical force will occur in a consistent direction of rotation, independent of the direction of applied voltage, but determined by the commutator and polarity of the field coils.

Milwaukee Electric Tool Power tool manufacturer

The Milwaukee Electric Tool Corporation is an American company that develops, manufactures, and markets power tools. It is a brand and subsidiary of Techtronic Industries, a Hong Kong-based company, along with AEG, Ryobi, Hoover, Dirt Devil, and Vax. It produces corded and cordless power tools, hand tools, pliers, hand saws, cutters, screwdrivers, trims, knives, and tool combo kits. It is since 2016 the biggest supplier of cordless power tools in North America, coming close with Bosch in second place, and Stanley Black and Decker at third place.

Skil Brand name of power tools

SKIL Power Tools is a brand of electric power tools and accessories which is based in Naperville, Illinois, United States. It is a subsidiary of Chervon, a company based in Nanjing, China.

Makita Japanese manufacturer of power tools

Makita Corporation is a Japanese manufacturer of power tools. Founded on March 21, 1915, it is based in Anjō, Japan and operates factories in Brazil, China, Japan, Mexico, Romania, the United Kingdom, Germany, Dubai, Thailand and the United States. Annual sales were equivalent to $2.9 billion in 2012.

Torque screwdriver

A torque screwdriver is a screwdriver with components that ensure tightening to a specified torque, ensuring tightening which is sufficient, but not excessive. An insufficiently tightened screw connection may loosen in operation, and excessive tightening can damage parts; for example, if the nuts holding the wheel of a car in place are too loose, or damaged by overtightening, a wheel may come off at speed. Torque screwdrivers are used in mechanical production, manufacturing, and maintenance; their use is part of quality assurance.

Brushcutter (garden tool) Powered garden tool

A brushcutter is a powered garden or agricultural tool used to trim weeds, small trees, and other foliage not accessible by a lawn mower or rotary mower. Various blades or trimmer heads can be attached to the machine for specific applications.

A Rail Drilling Machine is a type of portable drilling machine specialized for drilling holes in rails. Rail Drilling Machines are also popularly called as Rail Drills, Portable Rail Drill, Rail Core Drilling Machines, etc.

References

[1]

  1. "How Does a Saw's Electric Brake Work - Pro Tool Reviews". protoolreviews.com. 3 February 2017.