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The saw chain, or cutting chain, is a key component of a chainsaw. It consists of steel links held together by rivets, and superficially resembles the bicycle-style roller chain, although it is closer in design to a leaf chain. Its key differences are sharp cutting teeth on the outside of the chain loop, and flat drive links on the inside, to retain the chain on the saw's bar and allow propulsion by the engine or motor.
Saw chains (and chainsaws generally) are used for cutting wood. This may be for harvesting trees for pulp or timber, for tree surgery, or for processing firewood.
Whether for hand-held chainsaws, mechanical timber harvesters or chain mortisers, the saw chain has undergone dramatic development since its invention. Modern chains designed for high power, high-speed sawing applications will vastly outperform older designs, while allowing a far greater degree of safety and reliability in use.
Saw chains operate by being propelled around a guide bar, removing material from the kerf by cutting chips from the side and bottom. In order to operate properly, the depth to which each tooth cuts must be limited to avoid it binding in the wood. Scratcher chain, like the teeth on a hand saw, simply uses a multitude of teeth to prevent individual teeth from sinking too far in without undue pressure on the bar. Chipper chain, and all subsequent designs, incorporate a depth gauge (also known as a "raker" [1] ) on each cutter link to limit depth of cut on each tooth. This has two distinct advantages over scratcher chain – it enables the use of fewer cutters per unit length of chain, which allows for shorter downtime for sharpening, and produces a more "open" chain layout, allowing far better clearance of chips and debris from the kerf. Individual depth gauges on each tooth also enable the use of skip chain. Skip or semi-skip chain has a further reduction in the number of teeth and is used for applications where much debris is produced, such as ripping or cross-cutting very large sections of wood. Skip chain also absorbs less power from the motor per unit length of chain than full-complement chain, allowing the use of a longer bar/chain combination on any given motor.
Very early chainsaws used tooth configurations very similar to conventional hand saws. These were very simple saw teeth following a wave pattern (left, centre, right, centre) with no depth gauges as such, relying purely on bar pressure to limit the cutting rate. They were inefficient and slow in use, and were soon superseded by chipper chain. They required great skill and a lot of time to sharpen in the field leading to extended downtime between sessions.
Chipper chain invented by Joseph Cox improved dramatically on the performance of scratcher chain. Chipper used a tooth that was curled over the top of the chain, with alternate teeth pointing left and right. Ahead of the tooth was a depth gauge, which allowed for good clearance around the tooth for chip clearing while limiting the depth of cut and preventing grabbing or overloading. Chipper chains are sometimes used for dirty work, since their very large working corner allows the cutter to retain its effective sharpness for a long time in abrasive conditions.
Modern chains for general use in forestry, tree surgery and firewood cutting come in three basic configurations: the full chisel, the semi-chisel, and the chipper chain.
The full chisel chain has square-cornered teeth, splitting wood fibers easily in the cut for fast, efficient cutting in clean softwood. Chisel chains have a high kick-back risk due to missing safety chain elements and are more sensitive against dirt. These chains are available for semi-pro (also called pro-sumer) and professional saws.
The semi-chisel chain has teeth with rounded corners formed by a radius between the top and side plates. While slower than full chisel in softwood, it retains an acceptable cutting sharpness longer, making it the preferred choice for dirtier wood, hard or dry wood, frozen wood or stump work, all of which would rapidly degrade full chisel chain. They are similar to semi-chisel design but have a small 45 degree chamfer between the plates rather than a radius. Performance is similar to good semi-chisel. Semi chisel chains have a lower kick-back risk. These chains are available for consumer, semi-pro and professional saws.
Low-profile chains are chains with low teeth and safety elements between teeth. These chains are used on consumer and small professional saws for non-experienced operators. These chains are more insensitive against dirt, but require more frequent sharpening.
The chipper chain is similar to the semi-chisel chain. The key differences between are the size of the radius at the working corner. In cross-section a chipper tooth looks like a question mark, having a full radius over the whole cutting portion of the tooth, whereas a semi chisel design is more like a number "7" with the top-right corner slightly rounded.
There are also different arrangements of teeth on the chain.
Chain has a left cutter, drive link, right cutter, drive link arrangement and is used for most applications.
Has a left cutter, drive link, drive link, right cutter arrangement. It has one-third fewer cutting teeth and is generally used on long bars (≥24 in or 610 mm) for added chip clearance or when a bar longer than ideal for a given power head is used. Fewer teeth require less power to operate.
Alternates having one or two drive links between pairs of cutters, for performance in between that of full complement and skip arrangements.
The terms used to describe chain arrangements can be confusing. Most modern chains do not have only cutter teeth and drive links. There are tie straps which separate the cutters from each other.
Cutting chain comes in a large number of configurations, but these are reduced to a few key dimensions for replacement or specification purposes.
The gauge of the chain is the thickness of the drive links, and is dictated by the gauge of the bar on which it is to be run. Usual gauges are 0.043, 0.050, 0.058, 0.063 and 0.080 inches (1.1, 1.3, 1.5, 1.6 and 2.0 mm). [2] Chain and bar gauge must match; a chain that is too large will not fit, one that is too small will fall sideways and cut poorly.
The pitch of the chain is the average distance between two rivets. As the distance between rivets varies, the pitch can be measured by measuring between three rivets and dividing this distance by two. Typical pitches are 0.325, 0.375 and 0.404 inches (8.3, 9.5 and 10.3 mm). The 3⁄4-inch (19 mm) pitch is used for harvester applications, and very rarely for handheld cutting. The pitch of the chain must match the drive sprocket, and the nose sprocket (if fitted). Sprocket and rim can be in one unit or separated. [3]
A chain loop must be of an appropriate length in order to run safely. This is described by the number of drive links. This number is determined by the length and type of bar, the sprocket size and the overall configuration of the saw. For replacement purposes, simply count the drive links on the old chain.
Chains will naturally dull over time with use. The friction cause by cutting wood gradually wears the chain's teeth down. However, the technique of use can also contribute to a chain dulling quickly. Cutting at too sharp an angle, cutting into dirt, [4] and cutting frozen wood [5] can prematurely dull your chain.
The teeth of a chain come with a certain length. Wear and sharpening cause the teeth to become shorter. End-of-life is reached when the top of the head is too short.
A saw chain must be sharpened when the saw starts to vibrate or cuts poorly. The operator can feel the vibrations in the handles and the engine runs harder while cutting.
The length, gauge and number of drive links is punched on the side of the saw bar. This information can be found near the saw head. Since the saw bar should be turned 180 degrees between sharpenings, the punched information can be towards the saw power head or outside. It is also often found on a identification label under the handle depending on your brand of chainsaw.
Consult the saw's manual to determine which chain/bar combinations are compatible with the saw. A given saw will usually accept a number of different bars and chains.
A number of very specialised chain types have emerged over recent years. These include chains made of steel alloys optimised for cutting in extremely cold conditions, chains with tungsten carbide teeth for very dirty conditions and rescue work, ripping chains with altered blade geometry for making ripping cuts, and milling chains for chainsaw mills.
Chain mortisers, used to cut the mortice of large mortice and tenon timber framing, use a number of chains, riveted side-by-side. They are used with a vertical tip-first plunge. Owing to the difficulty of resharpening the multiple teeth, these are usually made of long-lasting tungsten carbide.
Chains are usually bought ready-joined to length, to suit a particular bar. All chainsaws have adjustable bar mounts to allow their chain tightness to be adjusted, allowing for any wear in the chain linkages. There is no requirement to remove links to shorten worn chains, chains will wear out on their cutting teeth before wear in their pivots becomes a problem. The adjustment also permits enough slack to allow a chain to be installed, so there is no need for a "split link" when fitting, as for bicycles.
Large scale operators and retail shops may buy bulk chain on reels. This must then be cut and joined to length which is done by inserting rivet pins. These non-reusable pins are usually supplied already installed into a half-link and must be peened over against a half-link on the other side. As this peening is done with a bench-mounted rotary tool, rather than hammering, it is referred to as "rivet spinning". The tool is usually hand-cranked, or may be electrically powered for mass production.
A circular saw or a 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 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.
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 usually operate by having a series of sharp points of some substance that is harder than the wood being cut. The hand saw is a bit like a tenon saw, but with one flat, sharp edge.
A chisel is a wedged hand tool with a characteristically shaped cutting edge on the end of its blade, for carving or cutting a hard material. The tool can be used by hand, struck with a mallet, or applied with mechanical power. The handle and blade of some types of chisel are made of metal or wood with a sharp edge in it.
A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge used to cut through material. Various terms are used to describe toothed and abrasive saws.
A chainsaw is a handheld saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. Modern chainsaws are used in activities such as tree felling, limbing, bucking, pruning, cutting firebreaks in wildland fire suppression, harvesting of firewood, for use in chainsaw art and chainsaw mills, for cutting concrete, and cutting ice. Precursors to modern chainsaws were first used in surgery, with patents for wood chainsaws beginning in the late 19th century.
A bicycle chain is a roller chain that transfers power from the pedals to the drive-wheel of a bicycle, thus propelling it. Most bicycle chains are made from plain carbon or alloy steel, but some are nickel-plated to prevent rust, or simply for aesthetics.
Hobbing is a machining process for gear cutting, cutting splines, and cutting sprockets using a hobbing machine, a specialized milling machine. The teeth or splines of the gear are progressively cut into the material by a series of cuts made by a cutting tool called a hob.
A file is a tool used to remove fine amounts of material from a workpiece. It is common in woodworking, metalworking, and other similar trade and hobby tasks. Most are hand tools, made of a case hardened steel bar of rectangular, square, triangular, or round cross-section, with one or more surfaces cut with sharp, generally parallel teeth. A narrow, pointed tang is common at one end, to which a handle may be fitted.
Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire- and tube-drawing machines, printing presses, cars, motorcycles, and bicycles. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission.
A saw filer is a person who maintains and repairs saws in a saw mill. A saw filer's work area in the mill is called the filing room.
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.
A crosscut saw is any saw designed for cutting wood perpendicular to (across) the wood grain. Crosscut saws may be small or large, with small teeth close together for fine work like woodworking or large for coarse work like log bucking, and can be a hand tool or power tool.
A ripsaw is a wood saw that is specially designed for making a rip cut, a cut made parallel to the direction of the wood grain.
A backsaw is any hand saw which has a stiffening rib on the edge opposite the cutting edge, enabling better control and more precise cutting than with other types of saws. Backsaws are normally used in woodworking for precise work, such as cutting dovetails, mitres, or tenons in cabinetry and joinery. Because of the stiffening rib, backsaws are limited in the depth to which they can cut. Backsaws usually have relatively closely spaced teeth, often with little or no set.
Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles.
Chainsaws and chainsaw operations have specific risk control methods.
Safety practices generally recommend that chainsaw users wear protective clothing, also known as personal protective equipment or PPE, while operating chainsaws. There is general agreement worldwide on what clothing is suitable, but local jurisdictions have specific rules and recommendations.
Milling cutters are cutting tools typically used in milling machines or machining centres to perform milling operations. They remove material by their movement within the machine or directly from the cutter's shape.
A scroll saw is a small electric or pedal-operated saw used to cut intricate curves in wood, metal, or other materials. The fineness of its blade allows it to cut more delicately than a power jigsaw, and more easily than a hand coping saw or fretsaw. Like those tools, it is capable of creating curved cuts with angled edges, by tilting its table along the axis of the cut.
This glossary of woodworking lists a number of specialized terms and concepts used in woodworking, carpentry, and related disciplines.