Garden Power Tools

The first power tool to become popular with gardeners was the lawn mower. This has been followed by a very wide range of power tools, including cultivators, string trimmer, Irrigation sprinklers, hedge trimmers, lawn aerators, leaf sweepers, leaf blowers, and mini-tractors. A lawn mower is a machine that uses revolving blades to cut a lawn at an even length.

Lawn mowers employing a blade that rotates about a vertical axis are known as rotary mowers, while those employing a blade assembly that rotates about a horizontal axis are known as cylinder or reel mowers. Many different designs have been made, each suited to a particular purpose. The smallest types, pushed by a human, are suitable for small residential lawns and gardens, while larger, self-contained, ride-on mowers are suitable for large lawns, and the largest, multi-gang mowers pulled behind a tractor, are designed for large expanses of grass such as golf courses and municipal parks.

Types of lawn mowers
The cylinder mower carries a fixed, horizontal cutting blade at the desired height of cut. Over this is a fast-spinning reel of blades which force the grass past the cutting bar. Each blade in the blade cylinder forms a helix around the reel axis, and the set of spinning blades describes a cylinder.
Of all the mowers, a properly adjusted cylinder mower makes the cleanest cut of the grass,[1] and this allows the grass to heal more quickly. The cutting action is often likened to that of scissors; however, it is not necessary for the blades of the spinning cylinder to contact the horizontal cutting bar.[1] If the gap between the blades is less than the thickness of the grass, a clean cut can still be made.

There are many variants of the cylinder mower. Push mowers (illustrated) have no motor and are used on small lawns. As the mower is pushed along, the wheels drive gears which rapidly spin the reel. Typical cutting widths are 12 to 20 inches (510 mm).Th e basic push mower mechanism is also used in gangs towed behind a tractor. The individual mowers are arranged in a vee behind the tractor with each mower's track slightly overlapping that of the mower in front of it. Gang mowers are used over large areas of turf such as sports fields or parks.

A gasoline engine or electric motor can be added to a reel mower to power the reel, the wheels, or both. A typical arrangement for residential lawns has the motor spinning the reel while the operator pushes the mower along. The electric models can be corded or cordless. Some variants have only 3 blades in a reel spinning at great speed, and these models can cut which has grown too long for ordinary push mowers. One type of reel mower, now largely obsolete, was a powered version of the traditional side wheel push mower and was used on residential lawns. An internal combustion engine sat atop the reel housing and drove the wheels, usually though a belt. The wheels in turn drove the reel, as in the push mower.

Greens (roller) mowers are used for the precision cutting of golf greens. The reel is followed by a large roller which smooth’s the freshly cut lawn and minimizes wheel marks. Due to the weight, the engine also propels the mower. Much smaller and lighter variants of the roller mower are sometimes used for small patches of ornamental lawns around flower beds, and these have no engine.

Riding reel mowers are also produced. Typically, the cutting reels are ahead of the vehicle's main wheels, so that the grass can be cut before the wheels push the grass over onto the ground. The reels are often hydraulically powered.

Rotary mowers

 A rotary mower (viewed from underneath), with a mulching blade that rotates around the center. Most rotary push mowers are powered by internal combustion engines. Such engines can be either two-stroke or four-stroke cycle engines, running on gasoline (petrol) or other liquid fuels. Internal combustion engines used with lawn mowers normally have only one cylinder. Power generally ranges from two to seven horsepower (1.5 to 6.75 kW). The engines are usually carbureted and require a manual pull crank to start them, although electric starting is offered on some models. Some mowers have a throttle control on the handlebar with which the operator can adjust the engine speed. Other mowers have a fixed, pre-set engine speed. Gasoline mowers have the advantages over electric mowers of greater power and distance range. However, they create substantial pollution and their engines require periodic maintenance such as cleaning or replacement of the spark plug and air filter.

Electric

Electric rotary lawn mower, with rear grass catcher (note the red cord attached at the handle). Electric mowers are further subdivided into corded and cordless electric models. Both are relatively quiet, typically producing less than 75 decibels, while a gasoline lawn mower can be as loud as 95 decibels or more. This kind of mower can also be safer to operate as they come equipped with a dead man's switch to immediately stop the motor when it is not being operated.

Corded electric
Corded electric mowers are limited in range by their trailing power cord, which may limit their use with lawns extending outward more than 100-150 feet from the nearest available power outlet. There is the additional hazard with these machines of accidentally mowing over the power cable, which stops the mower and may put users at risk of receiving a dangerous electric shock. Installing a residual-current device (GFCI) on the outlet may reduce the shock risk. On the United States market as of summer 2008, a corded electric mower from a respectable manufacturer costs about the same as an entry-level internal-combustion mower ($150–200), with significantly higher reliability, significantly lower cost of ownership, and a significantly reduced carbon footprint.

Cordless electric
Cordless electric mowers are powered by a variable number (typically 1-4) of 12 volt rechargeable batteries. Typically more batteries mean more run time and/or power. Batteries can be in the interior of the lawn mower or on the outside. If on the outside the drained batteries can be replaced with recharged batteries. Cordless mowers have the maneuverability of a gasoline powered mower and the environmental friendliness of a corded electric but are more expensive and come in fewer models (particularly self-propelling) than either.

Other

Hover mowers are powered rotary push lawn mowers that use a turbine above the spinning blades to drive air downwards, thereby creating an air cushion that lifts the mower above the ground. The operator can then easily move the mower as it floats over the grass. Hover mowers are necessarily light in order to achieve the air cushion and typically have plastic bodies with an electric motor. The most significant downside, however, is the cumbersome usability in rough terrain or on the edges of lawns, as the lifting air-cushion is destroyed by wide gaps between the chassis and the ground.

Robotic mower
A robotic mower is contained by a border wire around the lawn that defines the area to be mowed. The robot uses this wire to locate the boundary of the area to be trimmed and in some cases to locate a recharging dock. Robotic mowers are capable of maintaining up to 5 acres (20,000 m2) of grass. Robotic lawn mowers are increasingly sophisticated, are usually self-docking and contain rain sensors, nearly eliminating human interaction for mowing grass. Multiple robotic mowers can be used to mow an even larger area.

Riding mowers are a popular alternative for large lawns. The operator is provided with a seat and controls on the mower and literally 'rides' on the machine. Most use the horizontal rotating blade system, though usually with multiple blades. A common form of ride-on mower is the lawn tractor. These are usually designed to resemble a small agricultural tractor, with the cutting deck mounted amidships between the front and rear axles.

The drives for these mowers are in several categories. The most common transmission for tractors is a manual transmission. The second most common transmission type is a form of continuously variable transmission called the hydrostatic transmission. These transmissions take several forms, from pumps driving separate motors, which may incorporate a gear reduction, to fully integrated units containing a pump, motor and gear reduction. Hydrostatic transmissions are more expensive than mechanical transmissions but they are easier to use and can transmit greater torque to the wheels as compared to a typical mechanical transmission. The least common drive type, and the most expensive, is electric.

There have been a number of attempts to replace hydrostatic transmissions with a lower cost alternative, but these attempts, which include variable belt types (e.g., MTD's Auto Drive) and toroid, have various performance or perception problems that has caused their market life to be short or their market penetration to be limited. Riding lawnmowers can often mount other devices such as rototillers, snowplows, snow blowers, yard vacuums, occasionally even front buckets or fork-lift tines.

The deck of a rotary mower is typically made of steel. Lighter steel is used on less expensive models, and heavier steel on more expensive models for durability. Other deck materials include aluminum, which does not rust and is a staple of higher priced mowers, and hard composite plastic, which does not rust and is lighter and less expensive than aluminum. Electric mowers typically have a plastic deck.

Riding mowers typically have an opening in the side or rear of the housing where the cut grass is expelled. Some have a grass catcher attachment at the opening to bag the grass clippings. Special mulching blades are available for rotary mowers. The blade is designed to keep the clippings circulating underneath the mower until the clippings are chopped quite small. Other designs have twin blades to mulch the clippings to small pieces. This function has the advantages of forgoing the additional work collecting and disposing grass clippings while reducing lawn waste in such a way that also creates convenient compost for the lawn, forgoing the expense of fertilizer.

Mower manufacturers market their mowers as side discharge, 2-in-1, meaning bagging and mulching or side discharging and mulching, and 3-in-1, meaning bagging, mulching, and side discharge. Most 2-in-1 bagging and mulching mowers require a separate attachment to discharge grass onto the lawn. Some side discharge mower manufacturers also sell separate "mulching plates" that will cover the opening on the side discharge mower and, in combination with the proper blades, will convert the mower to a mulching mower.

These conversions are impractical when compared with 2- or 3-in-1 mowers which can be converted in the field in seconds. There are two types of bagging mowers. A rear bag mower features an opening on the back of the mower through which the grass is expelled into the bag. Hi-vac mowers have a tunnel that extends from the side discharge to the bag. Hi-vac is also the type of grass collection used on riding lawn mowers and lawn tractors and is considered more efficient. Mulching and bagging mowers are not well suited to long grass or thick weeds.

Rotary mowers with internal combustion engines come in three price ranges. Low priced mowers use older technology, smaller motors, and lighter steel decks. These mowers are targeted at the residential market and typically price is the most important selling point. These mowers are sold through large discount and home improvement stores, range between $100–400 on the US market, and have a typical service life of 7–10 years. Higher priced mowers are also primarily targeted at residential customers. These mowers have more features and often have heavier steel, composite plastic or aluminum decks. Most of these mowers are sold through independent dealers who also service the equipment and cost between $200 and $1000. These mowers will last as long as twenty years given regular maintenance.

Commercial grade mowers are the most expensive rotary mowers. They are "targeted" at grounds maintenance companies and other professionals, but are commonly sold to home owners as well. These mowers feature the latest technology and include features such as disk drive, oil filters, and very heavy steel and, more often, aluminum decks. These mowers are sold through independent dealers who service the product and, with regular maintenance; they have a service life far beyond twenty years. A commercial grade mower typically costs from $4,000 to as much as $90,000.

Professional grass-cutting equipment (used by large establishments such as universities, sports stadiums and local authorities) usually take the form of much larger, dedicated, ride-on platforms or attachments that can be mounted on, or behind, a standard tractor unit (a "gang-mower"). Either type may use rotating-blade or cylindrical-blade type cutters, although high-quality mowed surfaces demand the latter. Wide-area mowers (WAMs) are commercial grade mowers which have decks extended to either side, many to 12 feet (3.7 m). These extensions can be lowered for large area mowing or raised to decrease the mower's width and allow for easy transport on city roads or trailers.

Safety issues
Rotary mowers can throw out debris with tremendous force. In the US, over 80,000 people per year are hospitalized due to mower accidents. The vast majority of these injuries could be avoided by wearing footwear while mowing. The American Academy of Pediatrics recommends that children be at least 12 years old before they are allowed to mow.

Environmental impact
A 2001 study showed that some mowers emit the same amount of pollution (emissions other than carbon dioxide) in one hour as driving a 1992 model car for 650 miles (1,050 km). Another estimate puts the amount of pollution from a lawn mower at four times the amount from a car, per hour. Beginning in 2011, the United States Environmental Protection Agency has set standards for lawn equipment emissions and expects a reduction of at least 35%.
Mowers also cause significant noise pollution, and may cause hearing loss if used without hearing protection.

A "String Trimmer", also known as a Strimmer, string trimmer, line trimmer, Weed eater (a brand name), Weed whacker (a brand name) or weed whacker, Weed Whip, weedy, whipper sniper (in most parts of Australia), garden strimmer, grass trimmer, or Trimmer, is a powered handheld device that uses a flexible monofilament line instead of a blade for cutting grass and other plants near objects. It consists of a cutting head at the end of a long shaft with a handle or handles and sometimes a shoulder strap. String trimmers powered by an internal combustion engine have the engine on the opposite end of the shaft from the cutting head while electric string trimmers typically have an electric motor in the cutting head.

Designs
Electric edge trimmers have the advantage of being very light, easy to maneuver and easy-to-operate devices. However, the length of power cord that can be deployed across the ground limits them and they are usually less powerful and robust than the gasoline-engine ones. Electric machines normally are limited to 2.5 mm (0.100 inch) maximum diameter nylon because of their lower power output (400 to about 1200 watts). There are also battery-powered units available which have the benefit of being free of power cords, but the liability of weighing more due to a large battery and limited life before the battery runs down.

Gasoline-engine powered trimmers usually have a minimum of 21 cc displacement motors. At this size they can easily turn 2 mm (0.080 inch) line and some have nylon blades as accessories to the line-reel. A 32 cc engine can swing a 2.75 mm (0.110) line and often has metal-blade accessories. The head contains a safety shield on the user side and a rotating hub which may also be called a head or spool. While this type of trimmer is heavier, may use a gasoline-oil mix (if it is equipped with a two stroke engine) and vibrates significantly, they are much more mobile (not attached to a power outlet) and are not very limited in maximum power for commercial use. Large trimmers, used for cutting roadside grass in large areas, may be quite heavy—being suspended from the body by a harness — and may be a two-hand-controlled device. These very large trimmers are often referred to as brush cutters.

Trimmers that have nylon or metal blades usually have straight drive shafts because of the higher torque required to turn the disk and because of the shock loads that are passed back from the blade to the drive shaft and its gearbox. Smaller line trimmers have curved driveshaft’s to make holding the cutting-head at ground level much easier and with less strain on the operator.

Operation
A string trimmer works on the principle that a line that is turned fast enough is held out from its housing (the rotating reel) very stiffly by centripetal force. The faster it turns the stiffer the line. Even round-section nylon line is able to cut grass and slight, woody plants quite well. Some monofilament lines, designed for more powerful cutters, have an extruded shape—like a star—that helps the line slash the material being cut and thus it is able to cut quite large woody plants (small shrubs) or at least ring-bark them very effectively. These lines make disks less necessary for tough jobs.

The line is hand-wound onto a reel before the job is started, leaving both ends extending from the reel housing. The motor turns the reel and the line extends horizontally while the operator swings the trimmer about where the plants are to be trimmed. The operator controls the height at which cutting take place and can trim down to ground level quite easily. As the line is worn, or breaks off, the operator knocks the reel on the ground so that a release mechanism allows some of the line in the reel to extend and replace the spent portion. The newer models have an 'auto-feed' operation where a small cutter on the line-guard ensures that the line length exposed for cutting does not exceed the length that can be swung efficiently by the motor. Newly extended line operates more efficiently because of its heavier weight and surface effects (the star-shaped edges).

The speed of the spinning hub is usually controlled by a trigger on the handle. A common mistake is to run the trimmer at full speed when near objects. High speed near objects tends to wear or break line and damage objects without working faster. Running at a slower speed can actually shorten the job by requiring fewer passes and fewer stops to reload line or untangle the hub. The speed should be varied depending on the nature of nearby objects. Also, at slower speeds the line will whip around thinner objects without grabbing, eliminating additional passes near objects like sign poles and chain link fences. For vertical cutting the whole machine can be tilted or some trimmers allow the head to be adjusted at different angles.

Vertical cutting is not recommended near sidewalks or other concrete and pavement edges, because it leaves open grooves that allow water to collect and cause damage. Most trimmers use two stroke engines and require gasoline mixed with oil. Due to pollution laws four stroke engines are becoming more popular. For instance, Honda and MTD manufacture a four stroke engine trimmer. Other companies, such as John Deere, now carry Low Emission two stroke engine trimmers. Stihl manufactures a hybrid four stroke engine trimmer with no oil reservoir. This engine is lubricated using pre-mixed gasoline, like a two stroke engine.

Battery powered units are to be recharged after each use. As the recharge time is several hours long, battery powered units are ill-suited for trimming large yards. However, some models offer a quick-change battery pack so the user can have more than one battery ready to swap out when the first one runs down.

Environmental impact
The typical two-cycle engine used on string trimmers pollutes heavily as it does not burn the fuel completely in the cylinder. This results in unburned fuel escaping through the exhaust system and into the environment. US emission standards specifically limit emissions from small engines. Electric models produce no emissions at the point of use. Battery powered units typically use large sealed lead acid or nickel metal hydride batteries, which will wear out after a few years of use and must be disposed of properly.

The use of string trimmers at culturally or scientifically significant sites (e.g. cemeteries or in areas with rare plants) is often discouraged as a careless operator can inflict considerable damage to the significant items (e.g. headstones and rare specimens). However, for cost reasons, string trimmers are often employed at such sites as other forms of weed control are much more labor-intensive.

String breakage
One type of gross string breakage occurs when a segment, measuring back as little as an inch from the free end of the string, curves around a narrow fixed obstacle during higher speed operation. The term whiplash could be applied here, and as a function of time and stress, the elastic limit is exceeded at a sharp bend in the string, resulting in the initiation of a fracture. Segments that break off this way have a long smooth fracture angled towards parallel with the string. Care in operation can minimize this kind of breakage.

Accessories
Many string trimmers allow the hub, the head or the lower part of the shaft to be replaced with accessories. Common accessories include:

• Replacing the monofilament line with metal or plastic blades.
• Replacing the lower shaft with a small chain saw to create a powered pole saw.
• Replacing the lower shaft with a hedge trimmer.
• Replacing the lower shaft with a cultivator.

Quick release shafts are offered on many newer models which do not require any tools to switch in accessories. Typically only gasoline powered trimmers offer shaft powered accessories, as electric or battery driven units don't generate enough power.

Chain Saw
Chainsaw (or chain saw) is a portable mechanical saw, powered by electricity, compressed air, hydraulic power, or most commonly a two-stroke engine. It is used in activities such as tree felling, limbing, bucking, pruning, by tree surgeons to fell trees and remove branches and foliage, to fell snags and assist in cutting firebreaks in wild land fire suppression, and to harvest firewood. Chainsaws with specially designed bar and chain combinations have been developed as tools for use in chainsaw art. Specialist chainsaws are used for cutting concrete.

Chainsaw chain
A chainsaw consists of several parts.

• Engine — almost always a two-stroke gasoline (petrol) internal combustion engine, usually with a cylinder volume of 30-120 cm3 or electric motor.
• Drive mechanism — typically a clutch and sprocket.
• Guide bar — an elongated bar with a round end of wear-resistant alloy steel typically 16 to 36 inches in length. An edge slot guides the cutting chain.
• Cutting chain.

Usually each segment in this chain (which is constructed from riveted metal sections similar to a bicycle chain, but without rollers) features small sharp blades called teeth. Each tooth takes the form of a folded tab of chromium plate steel with a sharp angular or curved corner and two cutting edges on the top plate and side plate. Left-handed and right-handed teeth are alternated in the chain. Chains come in varying pitch and gauge; the pitch of a chain is defined as half of the length spanned by any three consecutive rivets (e.g., 0.325 inch), while the gauge is the thickness of drive link where it fits into the guide bar (e.g., 0.05 inch). Conventional "full complement" chain has one tooth per drive link. Built into each tooth is a depth gauge or "raker" which rides ahead of the tooth and limits the depth of cut, typically to around 0.025". Depth gauges are critical to safe chain operation. If left too high they will cause very slow cutting, if filed too low they will make the saw dangerous and hard to control.

The underside of each link features a small metal finger called a "drive link" which locates the chain on the bar, helps to carry lubricating oil around the bar, and engages with the engine's drive sprocket inside the body of the saw. The engine drives the chain around the track by a centrifugal clutch, engaging the chain under power but allowing it to stop as the engine idles.

Dramatic improvements, chainsaw safety devices and overall design have taken place since the chainsaw's invention, saving many lives and preventing countless serious injuries. These include chain brake systems, better chain design and anti-vibration systems. As chainsaw carving has become more popular, chainsaw manufacturers are making special short, narrow-tipped bars for carving. These are called "quarter tipped," "nickel tipped" or "dime tipped" bars, based on the size of the round tip. Echo sponsors a carving series, as well as carvers such as former Runaways singer Cherie Currie. RedMax specifically built the G3200 CV chainsaw for carving applications.

Maintenance
Most chainsaws require two sources of lubrication. Like most two-stroke engines, the engine is lubricated by its fuel, which contains about 2–5% oil (depending on the oil used) dissolved in the fuel. Separate chain oil or bar oil is used for the external lubrication of the bar and chain. The chain oil is depleted quickly because it tends to be thrown off the chain by centrifugal force, and it is soaked up by sawdust. The chain oil reservoir is usually topped up at the same time as refueling, and the reservoir is large enough so that the saw runs out of fuel and stops before the chain oil runs dry. Failing to keep the chain oil topped up, or using an oil of incorrect viscosity, is a common source of damage to saws, and tends to lead to rapid wear of the bar, or the chain jamming or coming off the bar.

In addition to being quite thick, chain oil is particularly sticky (due to "tackifier" additives) to reduce the amount thrown off the chain. Although motor oil is a common emergency substitute, it is lost even faster and so leaves the chain under lubricated. Chains must be kept sharp to perform well. They become blunt rapidly if they touch soil, metal or stones. When blunt, they tend to produce powdery sawdust, rather than the longer, clean shavings characteristic of a sharp chain; a sharp saw also needs very little force from the operator to push it into the cut. Special hardened chains (made with tungsten carbide) are used for applications where soil is likely to contaminate the cut, such as for cutting through roots.The air intake filter tends to clog up with sawdust. This must be cleaned from time to time, but is not a problem during normal operation.

Safety
A chainsaw operator wearing full safety gear using a gasoline-driven chain saw
Main articles: Chainsaw safety features and chainsaw safety clothing
Despite safety features and protective clothing, injuries can still arise from chainsaw use, from the large forces involved in the work, from the fast-moving, sharp chain, or from the vibration and noise of the machinery.

A common accident arises from kickback, when a chain tooth at the tip of the guide bar catches on wood without cutting through it. This throws the bar (with its moving chain) in an upward arc toward the operator, often causing serious injury or even death.

Another dangerous situation occurs when heavy timber begins to fall or shift before a cut is complete – the chainsaw operator may be trapped or crushed. Similarly, timber falling in an unplanned direction may harm the operator or other workers, or an operator working at a height may fall or be injured by falling timber.

Like other hand-held machinery, the operation of chainsaws can cause vibration white finger, tinnitus or industrial deafness.
The risks associated with chainsaw use mean that protective clothing and hearing protectors are normally worn while operating them, and many jurisdictions require that operators be certified or licensed to work with chainsaws. Injury can also result if the chain breaks during operation due to poor maintenance or attempting to cut inappropriate materials. Gasoline-powered chainsaws expose operators to harmful carbon monoxide (CO) gas, especially indoors or in partially enclosed outdoor areas.

Chainsaws for stone, concrete and brick

A chainsaw cutting concrete
Special chainsaws are used to cut concrete, brick and natural stone. These use similar chains to ordinary chainsaws, but with cutting edges embedded with diamond grit. They may be gasoline or hydraulically driven, and the chain is lubricated with water, because of high friction and to remove stone-dust. The machine is used in construction, for example in cutting deep square holes in walls or floors, in stone sculpture for removing large chunks of stone during pre-carving, by fire departments for gaining access to buildings and in restoration of buildings and monuments, for removing parts with minimal damage to the surrounding structure.

Because the material to be cut is non-fibrous, there is much less chance of kickback. Therefore the most-used method of cutting is plunge-cutting, by pushing the tip of the blade into the material. With this method square cuts as small as the blade width can be achieved. Pushback can occur if a block a shift when nearly cut through, and pinches the blade, but overall the machine is less dangerous than a wood

Band Saw
Band saw is a power tool which uses a blade consisting of a continuous band of metal with teeth along one edge to cut various work pieces. The band usually rides on two wheels rotating in the same plane, although some small band saws have three wheels. The saw may be powered by wind, water, steam, electrical motor or animal power. Band sawing produces uniform cutting action as a result of an evenly distributed tooth load. Band saws are used for woodworking, metalworking, or for cutting a variety of other materials, and are particularly useful for cutting irregular or curved shapes, but can also be used to produce straight cuts. The radius of a curve that can be cut on a particular saw is determined by the width of the band and its lateral flexibility.

Metal cutting

Brushes or brush wheels are sometimes used to remove chips from the blade as it exits the material. Band saws are available in vertical and horizontal designs. Band speeds range from 40 feet per minute to 5000 feet per minute.

Horizontal band saws may employ a gravity-fed blade or the rate of descent may be controlled by a hydraulic cylinder bleeding through an adjustable valve. When the saw is set up for a cut, the operator raises the saw by hand and the material is clamped in place and the saw is turned on, the blade slowly descending into the material, cutting it as the band blade moves. When the cut is complete, a switch is tripped and the saw automatically turns off.
Advancements have also been made in the band saw blades used to cut metals. The developments of new tooth geometries and tooth pitches have produced increased production rates and greater blade life. New materials and processes such as M51 steel and the cryogenic treatment of blades have produced results that were thought impossible just a few years ago. New machines have been developed to automate the welding process of band saw blades as well. Ideal computerized welding machines, setting and cut to length machines and contributions from other manufacturers continue to increase productivity.

Timber cutting
Timber mills use very large band saws for ripping lumber; they are preferred over circular saws for ripping because they can accommodate large-diameter timber and because of their smaller kerf (cut size), resulting in less waste. The blades range in size from about (4" wide x 19' long x 22 ga thickness) to (16" wide x 62' long x 11 ga thickness). The blades are mounted on wheels with a diameter large enough not to cause metal fatigue due to flexing when the blade repeatedly changes from a circular to a straight profile. It is stretched very tight (with fatigue strength of the saw metal being the limiting factor). Band saws of this size need to have a deformation worked into them that counteracts the forces and heating of operation. This is called benching. They also need to be removed and serviced at regular intervals. Saw filers are the craftsmen responsible for this work.

The shape of the tooth gullet is highly optimized and designed by the sawyer and saw filer. It varies according to the mill, as well as the type and condition of the wood. Frozen logs often require a frost notch ground into the gullet to break the chips. The shape of the tooth gullet is created when the blade is manufactured and its shape is automatically maintained with each sharpening. The saw filer will need to maintain the grinding wheel's profile with periodic dressing of the wheel.

Head saws
Head saws are large band saws that make the initial cuts in a log. They generally have a 2 to 3 in (51 to 76 mm) tooth space on the cutting edge and sliver teeth on the back. Sliver teeth are non-cutting teeth designed to wipe slivers out of the way when the blade needs to back out of a cut.

Resaws
A resaw is a large band saw optimized for cutting timber along the grain to reduce larger sections into smaller sections or veneers. Resawing veneers requires a wide blade - commonly 2 to 3 in (51 to 76 mm) - with a small kerf to minimize waste. Resaw blades of up to 1 in (25 mm) may be fitted to a standard band saw.

Double cut saws
Double cut saws have cutting teeth on both sides. They are generally very large, similar in size to a head saw.

Circular Saw
A good circular saw should have enough raw power to slice through everything from wet lumber to dense hardwood without bogging down. "When the motor slows, the blade heats up and dulls quickly," explains Tom Silva, This Old House general contractor. This not only produces a poor cut, it's dangerous because the blade can climb out of the kerf and push the saw back toward the user. However, evaluating power from the motor ratings can be misleading. Amps indicate only the amount of electricity a motor draws, not the power it sends to the blade. Horsepower accounts for torque (rotational force) generally under non-working conditions.

In the end, the most reliable appraisal may be price. A dependable sidewinder — the more compact design, in which the motor sits alongside the blade — starts at around $100. There are many saws on the market under this price, but they're not as powerful, nor are they built for a lifetime's use. Professional-grade sidewinders, which run quieter and cut through dense wood better, cost between $125 and $150. TOH master carpenter Norm Abram prefers this tool, noting that buyers should choose one based on balance and maneuverability. "I'd never buy a saw I didn't have a chance to hold first," he says.

On the other hand, a good worm-drive saw, Tom's choice for framing because of its high torque output (its beefy spiral gear transfers power to the blade more efficiently), will set you back at least $200. Either way, a top-of-the-line saw, if treated with care, should still be cutting well when you're readies to hand it down.

Worm Drive
The motor is in line with the blade, delivering enough torque to carve up wet lumber or saw through concrete, which makes a worm drive ideal for framing or major renovation jobs. With the handle farther back, a user can better resist kickback and steer the 16-pound saw through long rips.

Sidewinder
The motor sits alongside the blade, making for a lighter (11 pounds or less) saw, which is more maneuverable over a long day than a worm drive. The helical gearing on higher-end sidewinders, such as this Milwaukee 6390-20, beefs up the torque, making these models worthy competition for worm drives.

Small Sidewinder

Weight, balance, and handle size are all key features to consider when choosing a saw that fits you. For a slight-bodied person, a small pro model like this 7.7-pound Makita 5740NB may be more appropriate than a full-size sidewinder.
Cordless

Battery-driven models have increased in size as their power packs have gained voltage, making them convenient tools out in the field or when the electricity's not on. This Bosch 1660K sports a 6 ½-inch blade and a 24-volt battery — the largest in its class. However, cordless models still have limited run times and generate less torque than corded saws.

Trim saw

For finish work or paneling, Norm Abram prefers a small trim saw; blades range from 3½ to 412 inches. This Porter-Cable 314, with a 4½-inch blade, is the one worm drive on the market — all others are sidewinders. Ease of Adjustment. Large, smooth-cornered lever locks and full-round knobs that can be tightened down with the whole hand, like this one on the DeWalt 364, make it faster and easier to change the depth of cut and bevel settings than small, hard-to-grasp levers and wing nuts.

Shoe Styles
"No matter what you do, you will drop your saw," warns Tom Silva. Cast-metal shoes with raised reinforcing ribs on the top surface, as seen here on a Porter-Cable 347, won't bend like flat aluminum shoes if the saw hits the ground. On the other hand, a cast metal shoe adds weight to a saw. Circular saws can be dangerous. Always wear safety glasses and follow the safety instructions printed in your saw's owner's manual

Electric Saw
Electric chainsaws are a fantastic invention, which makes using a chainsaw easy to use and safe. Electric saws are beneficial because they are usually lighter, smaller and much easier to maneuver, making them a perfect option for most households needing it for yard work. Electric saws are also much safer since they kickback a lot less and since they are quieter your neighbors will be happier with your electric version.

Jigsaw
A jigsaw is a tool used for cutting arbitrary curves, such as stenciled designs or other custom shapes, into a piece of wood, metal, or other material. It can be used in a more artistic fashion than other saws, which typically only cut in straight lines. In this way, it is similar to the rasp and the chisel. Although a jigsaw can be used to cut arbitrary patterns, making a straight cut freehand is difficult even with a guide.

Traditional jigsaws are hand saws, consisting of a handle attached to a small, thin blade. The first jigsaw puzzles were made using this kind of unpowered saw. More modern jigsaws are power tools, made up of an electric motor and a reciprocating saw blade. A jigsaw with a bevel function on the sole plate allows cutting angles of typically up to 45 degrees relative to the normal vertical stroke for cutting miter joints. In the past, what are now usually called scroll saws, were often referred to as jigsaws. A Jigsaw may also be referred to, by some manufacturers, as a "bayonet saw".

Blades
There are 2 main types of blade fitting in use. The older type uses a screw to hold the blade, the newer type slots in.
A wide variety of blade types are used, including:

•  various numbers of TPI
• blade edge for cutting soft materials
• cranked blades to overcome the setback of the blade and allow flush cutting
• thin blades to allow tighter curves to be cut
• Push stroke cutting blades to avoid damage to the top surface. These are problematic to use
  

Controllability
Control is an issue with jigsaws. The blades are small, weak and entirely unsupported at the lower end. Good cut control requires the use of blade rollers, which keep the blade aligned just above the sole plate. Heavy cast sole plate saws are better than pressed steel for control too. To guide a jigsaw, it must be steered (turned) rather than simply moved sideways

Hedge Trimmer
A hedge trimmer is a piece of gardening/agricultural equipment used for trimming hedges. Motorised hedge trimmers allow work to be done faster and with less effort than manual ones.

Stand-alone
The power source can be human power, gasoline, or electricity. The first type does not need anything to operate and is cheapest/most environmentally friendly. The former tend to be more powerful but can be heavier and more difficult to start. The latter tend to be lighter and less powerful (than gasoline variants) as well as less polluting, yet still require an electrical cord with most types. Powered hedge trimmers are generally designed with safety devices such that they work only when both of the operator's hands are on the handles.

Tractor mounted
A tractor-driven version of trimmers exist as well (not shown), which allows easy trimming/pruning of plants and food crops. More specifically, types exist with a movable arm and types without a movable arm (relying solely on rotating blades on 2 central pivots placed on the tractor's side). These latter are used in grape-growing (for making wine), by using small tractors that drive between the grape vines.

Garden cultivators
A small tiller
Small cultivators are used for gardening, powered by small motors, and controlled by an operator walking behind. Garden cultivators can be used to mix soils with manures and fertilizers in preparation for planting. They till the soil and convert soil lumps to a tilth. Different attachments can be used to plough the soil or cut vegetation.

Garden Vacuum Blower
A leaf blower is a gardening tool that propels air out of a nozzle to move yard debris such as leaves. Leaf blowers are usually powered by two-stroke engine or an electric motor, but four-stroke engines were recently introduced to partially address air pollution concerns. Leaf blowers are typically self-contained handheld units, or backpack mounted units with a handheld wand. The latter is more ergonomic for prolonged use. Some units can also suck in leaves and small twigs via a vacuum, and shred them into a bag. In that role it is called a blower vac.

Irrigation Sprinklers
Irrigation sprinklers are sprinklers used on farms, golf courses, and yards, to provide water to vegetation and plants in the event of drought. They may also be used for recreation, as a cooling system, or to keep down the amount of airborne dust.Many irrigation sprinklers are buried in the ground along with their supporting plumbing, although above ground and moving sprinklers are also common. Most irrigation sprinklers operate through electric and hydraulic technology and are grouped together in zones that can be collectively turned on and off by actuating a solenoid-controlled valve.

Residential sprinklers
Home lawn sprinklers vary widely in their size, cost, and complexity. They include impact sprinklers, oscillating sprinklers, drip sprinklers, and underground sprinkler systems. Small sprinklers are available at home and garden stores or hardware stores for small costs. These are often attached to an outdoor water faucet and are placed only temporarily. Other systems may be professionally installed permanently in the ground and are attached permanently to a home's plumbing system.

Permanently installed system may often operate on timers or other automated processes. They are occasionally installed with retractable heads for aesthetic and practical reasons (making damage during lawn mowing or other maintenance less likely). These often are programed to operate at certain times of day or on some other schedule.

Underground sprinklers
Underground sprinklers function through means of basic electronic and hydraulic technology. This valve and all of the sprinklers that will be activated by this valve are known as a zone. Upon activation, the solenoid, which sits on top of the valve, is magnetized lifting a small stainless steel plunger in its center. By doing this, the activated (or raised) plunger allows air to escape from the top of a rubber diaphragm located in the center of the valve. Water that has been charged and waiting on the bottom of this same diaphragm now has the higher pressure and lifts the diaphragm. This pressurized water is then allowed to escape downstream of the valve through a series of pipes, usually made of PVC. At the end of these pipes and flush to ground level (typically) are pre measured and spaced out sprinklers. These sprinklers can be fixed spray heads that have a set pattern and generally spray between 1.5-2m (7–15 ft.), full rotating sprinklers that can spray a broken stream of water from 6-12m (20–40 ft.), or small drip emitters that release a slow, steady drip of water on more delicate plants such as flowers and shrubs.

Sprinkler use
Most irrigation sprinklers are used as part of a sprinkler system, consisting of various plumbing parts, piping and control equipment. Piping is connected to the water source via plumbing fittings and the control system opens and closes valves to provide water on a schedule. The control provided varies depending on the equipment used; some systems are fully automated and even compensate for rain, runoff and evaporation, while others require much more user attention for the same effectiveness.

Outdoor sprinkler systems are sometimes used as a deterrent against homeless people. For example, the city of Los Angeles installed an elaborate overhead sprinkler system in a downtown park along lower Fifth Street. This sprinkler system was programmed to drench unsuspecting sleepers at random times during the night. Local businessmen soon copied this system in an effort to drive homeless people away from public sidewalks adjacent to their businesses.

Keep your lawn thriving and green with the help of a sprinkler or in ground irrigation. Green grass, blooming flowers and full, leafy trees are all signs of a healthy lawn. With proper watering habits you can be sure to enjoy a lush, vibrant yard, and the right sprinklers are the key to your success. With such a wide range of available models, it's important to know which one is ideal for your particular lawn. You'll want to consider a number of factors when choosing a new sprinkler. It may even be necessary to utilize more than one type to ensure that your yard is sufficiently covered. Keeping your lawn healthy and green enhances the look of your home, so consider the following questions as you shop to ensure you're getting maximum watering.

• How large is the area that needs to be watered?
• How frequently should you water?
• What type of sprinkler will work best for your yard?
• What is the climate like in your region?
• How can you most effectively water hard-to-reach areas, like gardens?

Sprinkler Types and Watering Tips
Choosing the right type of sprinkler will go a long way toward ensuring its efficiency. The size of your lawn and the area to be watered will play a large role in determining which sprinkler is best, as will how active you wish to be in the process. If you love working on your lawn and wish to closely monitor it on a daily basis, you'll probably want to choose sprinklers that require a little more time and attention. If you want green grass but don't have the time to look after each section of your lawn, an automatic in-ground irrigation system may be an ideal solution. Regardless of which type of sprinkler you employ, you'll want to keep a few basic watering tips in mind to ensure that you provide enough - and not too much - water for your lawn to grow.

Types: Knowing the differences between the many types of sprinklers available will help you choose the best fit for your lawn. Fixed, or stationary, sprinklers feature several different designs including rings and "salt shakers." They cast water in a single pattern over a fixed area. Oscillating sprinklers have a long tube with numerous openings and move back and forth, emitting a fan-shaped waterfall. Impact sprinklers, sometimes called impulse sprinklers, rotate in a circle and squirt out a single jet of water, making a distinctive clicking sound as they do. Rotating sprinklers feature two or more arms and spin to disperse water in a complete circle. Sprinkler hoses lie along the ground and squirt water from tiny holes to cover a long, rectangular area. Traveling sprinklers often look like little tractors and move through your yard in a preset pattern, dragging the hose behind them. Finally, in-ground sprinkler systems are installed into the lawn and pop up at a designated time, usually cycling their way through the yard to provide complete coverage.

Watering Tips: While having the right sprinkler will certainly make watering your lawn much easier, there are other steps you'll need to take to ensure maximum effectiveness. Lawns and gardens require much more water when the weather is sunny than they do when it's cloudy, so make sure you're using your sprinklers more frequently on hot summer days. Because grass is composed primarily of water, it is particularly vulnerable in high-heat, low-water conditions. In addition to weather, the type of soil you have will dictate how frequently you need to water. If you're unsure of when to water, look for changes in grass and plants as slow or arrested growth and browning will give you an indication that more moisture is needed. Water your lawn early in the morning so water doesn't evaporate as quickly as it does during the hotter parts of the day and to give grass sufficient time to dry before nightfall.

• Constant wetness can lead to disease and insect infestation.
• Intermittent watering over several hours provides thorough root penetration
• Sandy soil needs short, frequent periods of water
• Clay soil requires less watering than sandy soil
• Loam soil holds water longer than sandy soil but not as long as clay
• Watering is unnecessary during periods of heavy rain
• Allow soil to dry between watering’s

Automatic Timer: A common feature of in-ground sprinkler systems, automatic timers allow you to choose when you want sprinklers to go on or off, so you can start watering early in the morning without having to crawl out of bed to turn them on.

Flow Timer: Sprinklers with this feature monitor the amount of water they emit and let you calibrate it to a specific setting. This will allow you to customize the amount of water you're using to ensure thorough soaking on different parts of your lawn.

Automatic Shutoff Valve: A good feature to have in traveling sprinklers, these valves automatically cut off the water supply once the sprinkler has completed its pattern to ensure that water is not wasted and your lawn doesn't get waterlogged.