The router[lower-alpha 1] is a power tool with a flat base and a rotating blade extending past the base. The spindle may be driven by an electric motor or by a pneumatic motor. It routs (hollows out) an area in hard material, such as wood or plastic. Routers are used most often in woodworking, especially cabinetry. They may be handheld or affixed to router tables. Some woodworkers consider the router one of the most versatile power tools.[1]
There is also a traditional hand tool known as a router plane, a form of hand plane with a broad base and a narrow blade projecting well beyond the base plate.
The laminate trimmer is a smaller, lighter version of the router. Although it is designed for trimming laminates, it can also be used for smaller general routing work.
Rotary tools can also be used similarly to routers with the right bits and accessories (such as plastic router bases).
History
Before power routers existed, the router plane was often used for the same purpose.
An incremental step toward modern power routers was the foot-pedal operated router, such as the Barnes Former/Shaper, available in 1877.[2] Barnes patented a reversible rotary cutting head in 1889.[3]
The first portable power router was patented in 1906 by George Kelley and marketed by the Kelley Electric Machine Company.[4] The early electric routers were quite heavy,[5] and only nominally "portable".
In 1915 Oscar and Rudy Onsrud produced an air-powered router, which they referred to as a Jet Motor Hand Router.[6]
In the 1930s, Stanley Works acquired a line of portable routers from Roy L. Carter, and marketed an 18000 RPM electric hand router similar to modern routers.[7]
Further refinement produced the plunge router, invented by ELU (now part of DeWalt) in Germany around 1949.
Modern routers are often used in place of traditional moulding planes or spindle moulder machines for edge decoration (moulding) of timber.
Process
Routing is a high speed process of cutting, trimming, and shaping wood, metal, plastic, and a variety of other materials.
Chip formation
Modern plunge router showing dust extraction tube
Routing and milling are conceptually similar, and end mills can be used in routers, but routing wood is different from milling metal in terms of the mechanics. Chip formation is different, so the optimal tool geometry is different. Routing is properly applied to relatively weak and brittle materials, typically wood. As these materials are weak in small sections, routers can run at extremely high speeds, so even a small router may cut rapidly. Owing to inertia at these high speeds, the normal wood cutting mechanism of Type I chips cannot take place. The cutter edge angle is blunt, approaching 90°, and so a Type III chip forms, with waste material produced as fine dust. This dust is a respiratory hazard, even in benign materials. The forces against the cutter are light, so routers may be hand-held.
When milling metals, the material is relatively ductile, although remaining strong even at a small scale. A Type II chip forms, and waste may be produced as continuous swarf. Cutter forces are high, so milling machines must be robust and rigid, usually substantial constructions of cast iron.
Intermediate materials, such as plastics and sometimes soft aluminium, may be cut by either method, though routing aluminium is usually more of an improvised expedient than a production process, and is noisy and hard on tools.
Routing is usually limited to soft metals (aluminium etc.) and rigid non-metals. Specially designed cutters are used for a variety of patterns, cuts, and edging. Both hand controlled and machine controlled/aided routers are common today.
Workpiece geometry
Routing is a shaping process that produces finished edges and shapes. Some materials that are difficult to shape with other processes, such as fiber-glass, Kevlar, and graphite, can be shaped and finished neatly via various routing techniques. Apart from finished edges and shaping, cutaways, holes, and contours can also be shaped using routers.
Tools and equipment
The set up includes an air or electric driven router, a cutting tool often referred to as a router bit, and a guide template. Also the router can be fixed to a table or connected to radial arms which can be controlled more easily.
In general there are three types of cutting bits or tools.
Fluted cutters (used for edging and trimming)
Profile cutters (used for shaping and trimming)
Helical cutters (used on easily machined materials, for drilling, shaping, trimming)
Safety glasses and ear protection should be worn at all times when using a router.
Only trained adults, or trained adolescents with supervision, should use the router.
Moulding
The spindle router is positioned at the finer end of the scale of work done by a molding spindle. That is to say it is able to cut grooves, edge molding, and chamfer or radius the edge of a piece of wood. It is also possible to use it for cutting some joints. The shape of cut that is created is determined by the size and shape of the bit (cutter) held in the collet and the depth by the depth adjustment of the sole plate.
Variety of routers
There are a variety of router styles, some are plunge, some are D handled, some are double knob handled. Different manufacturers produce the routers for different wood works, as plunge routers, fixed-base wood routers, combo routers, variable-speed routers, laminate trimmers, CNC wood routers.[citation needed] Nowadays, most better quality routers have variable speed controls and will have plunge bases that can also be locked in place so the router can be used as a fixed-base router.[citation needed] Some have a soft-start feature, meaning they build up speed gradually. This feature is particularly desirable for routers with a large cutter. Holding a 3-horsepower router and turning it on without a soft-start is potentially dangerous, due to the torque of the motor. Holding it with two hands is a must. For routers with a toggle type on/off switch it is important to check to verify the switch is in the off position, prior to plugging it in. For safety, larger router cutters can usually only be used in a router that is mounted in a router table. This makes the tool even more versatile and stable.[citation needed]
The purpose of multiple handle arrangements depends on the bit. Control is easier with different configurations. For example, when shaping the edge of a fine table top, many users prefer a D handle, with variable speed, as it seems to permit better control and burning the wood can be minimized.
Routers have many uses. With the help of the multitude of jigs and various bits, they are capable of producing dovetails, mortises, and tenons, moldings of infinite varieties, dados, rabbets/rebates, raised-panel doors and frames, cutting circles, and so much more.[citation needed]
Features of the modern spindle router
Template guide bushing secured in the base around the router cutter
The tool usually consists of a base housing a vertically mounted universal electric motor with a collet on the end of its shaft. The bit is height-adjustable to allow protrusion through an opening in a flat sole plate, usually via adjusting the motor-mounting height (the mechanism of adjustment is widely varied among manufacturers). Control of the router is derived from a handle or knob on each side of the device, or by the more recently developed "D-handle".
There are two standard types of router—plunge and fixed. When using a plunge-base router, the sole of the base is placed on the face of the work with the cutting bit raised above the work, then the motor is turned on and the cutter is lowered into the work. With a fixed-base router, the cut depth is set before the tool is turned on. The sole plate is then either rested flat on the workpiece overhanging the edge so that the cutting bit is not contacting the work (and then entering the work from the side once the motor is turned on), or the sole plate is placed at an angle with the bit above the work and the bit is "rocked" over into the work once the motor is turned on. In each case, the bit cuts its way in, but the plunge router does it in a more refined way, although the bit used must be shaped so it bores into the wood when lowered.
The baseplate (sole plate) is generally circular (though this, too, varies by individual models) and may be used in conjunction with a fence attached to the base, which then braces the router against the edge of the work, or via a straight-edge clamped across the work to obtain a straight cut. Other means of guiding the machine include the template guide bushing secured in the base around the router cutter, or router cutters with built-in guide bearings. Both of these run against a straight edge or shaped template. Without this, the varying reaction of the wood against the torque of the tool makes it impossible to control with the precision normally required.
Table mounted router
View underneath a router table showing plunge router attached.
A router may be mounted upside down in a router table or bench. The router's base plate is mounted to the underside of the table, with a hole allowing the bit to protrude above the table top. This allows the work to be passed over the router, rather than passing the router over the work. This has benefits when working with smaller objects and makes some router operations safer to execute. A router table may be fitted with a fence, fingerboards and other work-guiding accessories to make the operation safer and more accurate.
A simple router table consists of a rigid top with the router bolted or screwed directly to the underside. More complex solutions can be developed to allow the router to be easily removed from the table as well as facilitate adjusting the router's bit height using a lift mechanism; there is a wide range of commercially available systems.
In this mode, the router can perform tasks similar to a spindle moulder. For smaller, lighter jobs, the router used in this way can be more convenient than the spindle moulder, with the task of set up being somewhat faster. There is also a much wider range of bit profiles available for the router, although the size is limited.
The router table is usually oriented so that the router bit is vertical and the table over which the work is passed is horizontal. Variations on this include the horizontal router table, in which the table remains horizontal but the router is mounted vertically above the table, so that the router bit cuts from the side. This alternative is for edge operations, such as panel raising and slot cutting.
Available cutters
Profiles made in wood by several common router bits.Two typical router bits: (top) a 1⁄4-inch shaft Roman Ogee with bearing, (bottom) 1⁄4-inch shaft dovetail bit.
Router bits come in a large variety of designs to create either decorative effects or joinery aids. Generally, they are classified as either high-speed steel (HSS) or carbide-tipped, however some recent innovations such as solid carbide bits provide even more variety for specialized tasks.
Aside from the materials they are made of, bits can be classified as edge bits or non-edge bits, and whether the bit is designed to be anti-kickback. Edge bits have a small wheel bearing to act as a fence against the work in making edge moldings. These bearings can be changed by using commercially available bearing kits. Changing the bearing, in effect, changes the diameter of the cutting edge. This is especially important with rabbeting/rebating bits. Non-edge bits require the use of a fence, either on a router table or attached to the work or router. Anti-kickback bits employ added non-cutting bit material around the circumference of the bit's shoulders which serves to limit feed-rate. This reduces the chance that the workpiece is pushed too deeply into the bit (which would result in significant kickback from the cutting edge being unable to compensate).
Bits also differ by the diameter of their shank, with 1⁄2-inch, 12mm, 10mm, 3⁄8-inch, 8mm and 1⁄4-inch and 6mm shanks (ordered from thickest to thinnest) being the most common. Half-inch bits cost more but, being stiffer, are less prone to vibration (giving smoother cuts) and are less likely to break than the smaller sizes. Care must be taken to ensure the bit shank and router collet sizes match exactly. Failure to do so can cause permanent damage to either or both and can lead to the dangerous situation of the bit coming out of the collet during operation. Many routers come with removable collets for the popular shank sizes (in the US 1⁄2in and 1⁄4in, in Great Britain 1⁄2in, 8mm and 1⁄4in, and metric sizes in Europe—although in the United States the 3⁄8in and 8mm sizes are often only available for an extra cost).
Many modern routers allow the speed of the bit's rotation to be varied. A slower rotation allows bits of larger cutting diameter to be used safely. Typical speeds range from 8,000 to 30,000 rpm.
Router bits can be made to match almost any imaginable profile. Custom router bits can be ordered. They are especially beneficial for home restoration projects, where production of the original trim and molding has been discontinued.
Sometimes complementary bits come in sets designed to facilitate the joinery used in frame and panel construction. One bit is designed to cut the grove in the rail and stile pieces while the other shapes the edge of the panel to fit in the grove.
CNC router
A CNC wood router is a computer controlled machine to which the router or spindle mounts. The CNC Machine can be either a moving gantry style, where the table is fixed and the router spindle moves over it, or fixed bridge design, where the table moves underneath the router spindle, or hand-held style, where the operator moves the machine to the area to be cut and the machine controls the fine adjustments. CAD/CAM software programming is used to model the part that is to be created in the computer and then create a tool path for the machine to follow to cut out the part. The CNC moves along three axes (X-Y-Z). Most CNC routers have a three motor drive system utilizing either servo or stepper motors. More advanced routers use a four motor system for added speed and accuracy.
Similar tools
A tool similar to a router, but designed to hold smaller cutting bits—thereby making it easier to handle for small jobs—is a laminate trimmer.
A related tool, called a spindle moulder (UK) or shaper (North America), is used to hold larger cutter heads and can be used for deeper or larger-diameter cuts. Another related machine is the pin router, a larger static version of the hand electric router but normally with a much more powerful motor and other features such as automatic template copying.
Some profile cutters use a cutting head reminiscent of a spindle router. These should not be confused with profile cutters used for steel plate which use a flame as the cutting method.
A lathe is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis.
Drill bits are cutting tools used in a drill to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes drill bits are usually attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck.
In machining, numerical control, also called computer numerical control (CNC), is the automated control of tools by means of a computer. It is used to operate tools such as drills, lathes, mills, grinders, routers and 3D printers. CNC transforms a piece of material into a specified shape by following coded programmed instructions and without a manual operator directly controlling the machining operation.
Drilling is a cutting process where a drill bit is spun to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the work-piece, cutting off chips (swarf) from the hole as it is drilled.
A CNC wood router is a CNC router tool that creates objects from wood. CNC stands for computer numerical control. The CNC works on the Cartesian coordinate system for 3D motion control. Parts of a project can be designed in the computer with a CAD/CAM program, and then cut automatically using a router or other cutters to produce a finished part. The CNC router is ideal for hobbies, engineering prototyping, product development, art, and production work.
The phrase speeds and feeds or feeds and speeds refers to two separate velocities in machine tool practice, cutting speed and feed rate. They are often considered as a pair because of their combined effect on the cutting process. Each, however, can also be considered and analyzed in its own right.
A collet is a segmented sleeve, band or collar. One of the two radial surfaces of a collet is usually tapered and the other is cylindrical. The term collet commonly refers to a type of chuck that uses collets to hold either a workpiece or a tool but has other mechanical applications.
A laminate trimmer is a small version of a wood router, normally used to trim laminate such as Formica. It generally has a 1/4-inch collet. Typical laminate trimmers spin their bits at up to 30,000 RPM. Some models provide variable speed control. Manufacturers of note include DeWalt, Ryobi, Porter Cable, Ridgid, Makita and RotoZip (Bosch).
A wood shaper, is a stationary woodworking machine in which a vertically oriented spindle drives one or more stacked cutter heads to mill profiles on wood stock.
A Tool and Cutter Grinder is used to sharpen milling cutters and tool bits along with a host of other cutting tools.
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
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.
Burrs or burs are small cutting tools; not to be confused with small pieces of metal formed from cutting metal, used in die grinders, rotary tools, or dental drills. The name may be considered appropriate when their small-sized head is compared to a bur or their teeth are compared to a metal burr.
In machining, a metal lathe or metalworking lathe is a large class of lathes designed for precisely machining relatively hard materials. They were originally designed to machine metals; however, with the advent of plastics and other materials, and with their inherent versatility, they are used in a wide range of applications, and a broad range of materials. In machining jargon, where the larger context is already understood, they are usually simply called lathes, or else referred to by more-specific subtype names. These rigid machine tools remove material from a rotating workpiece via the movements of various cutting tools, such as tool bits and drill bits.
An end mill is a type of milling cutter, a cutting tool used in industrial milling applications. It is distinguished from the drill bit in its application, geometry, and manufacture. While a drill bit can only cut in the axial direction, most milling bits can cut in the radial direction. Not all mills can cut axially; those designed to cut axially are known as end mills.
An indexing head, also known as a dividing head or spiral head, is a specialized tool that allows a workpiece to be circularly indexed; that is, easily and precisely rotated to preset angles or circular divisions. Indexing heads are usually used on the tables of milling machines, but may be used on many other machine tools including drill presses, grinders, and boring machines. Common jobs for a dividing head include machining the flutes of a milling cutter, cutting the teeth of a gear, milling curved slots, or drilling a bolt hole circle around the circumference of a part.
In machine tools, a spindle is a rotating axis of the machine, which often has a shaft at its heart. The shaft itself is called a spindle, but also, in shop-floor practice, the word often is used metonymically to refer to the entire rotary unit, including not only the shaft itself, but its bearings and anything attached to it. Spindles are electrically or pneumatically powered and come in various sizes. They are versatile in terms of material it can work with. Materials that spindles work with include embroidery, foam, glass, wood, etc.
A computer numerical control (CNC) router is a computer-controlled cutting machine which typically mounts a hand-held router as a spindle which is used for cutting various materials, such as wood, composites, metals, plastics, glass, and foams. CNC routers can perform the tasks of many carpentry shop machines such as the panel saw, the spindle moulder, and the boring machine. They can also cut joinery such as mortises and tenons.
A router table is a stationary woodworking machine in which a vertically oriented spindle of a woodworking router protrudes from the machine table and can be spun at speeds typically between 3000 and 24,000 rpm. Cutter heads may be mounted in the spindle chuck. As the workpiece is fed into the machine, the cutters mold a profile into it. The machine normally features a vertical fence, against which the workpiece is guided to control the horizontal depth of cut. Router tables are used to increase the versatility of a hand-held router, as each method of use is particularly suited to specific application, e.g. very large workpieces would be too large to support on a router table and must be routed with a hand-held machine, very small workpieces would not support a hand-held router and must be routed on a router table with the aid of pushtool accessories etc.
Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This may be done by varying directions on one or several axes, cutter head speed, and pressure. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.
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