Glossary

Amp Hour
Describes the overall storage capacity of a battery. A 3.0 Amp Hour battery can provide 3 amps of current for 1 hour or 1.5 amps of current for 2 hours, etc. The greater the amp hour rating of a battery the longer it can run a tool. Note that many things affect the real life performance of batteries such as: overall efficency, battery chemistry, voltage etc. So eventhough batteries may have the same Amp Hour rating, not all batteries are created equal.

Amperage
Also known as current, amperage is the amount of electrical energy flowing through a wire at a specific given time. The unit of measurement is expressed in amperes which is often shortened to amps. The amount of power used by a tool is the product of the amperage and the voltage (P=VI) so that a tool with a higher amperage rating will consume more power and generally generate more torque than a tool with a lower amperage rating.

Arbor
In power tools, a mandrel or arbor refers to a machine piece which holds or clamps circular saw blades, buffing wheels (used for polishing), and sanding discs onto drills, circular saws, and similar power tools. This type of mandrel usually consists of a threaded cylinder and an accompanying nut to hold the blade or disc.

Bench Dog
A round or square peg made of wood or metal that fits into a hole in a workbench to hold a workpiece in place.

Biscuit
A thin, flat, football shaped compressed wood piece used to increase the strength of butt-joints. A specialized tool called a biscuit or plate joiner is usually used to cut a mortise for the biscuit. When water from glue comes in contact with the biscuit (usually birch), it swells to make a tight joint.

Carbide
A very hard material fused to the cutting edges of saw blades, router bits, drill bits, etc. Carbide (titanium carbide, tunsgsten carbide) is very brittle, but maintains a very sharp edge. Typically carbide is bonded to the cutting edge of a steel blade or bit giving the superior sharpness of a carbide edge, with the resilance of a steel tool. Carbide edges can be resharpend with the appropriate tools giving them long life.

Chuck
An attachment to a drill that holds the bit in place. There are a variety of types of chucks that work with or without keys. Most hand-drills sold today are equipped with a keyless chuck while drill presses typically still use the old Jacobs-style chuck that requires a key to remove bits or secure a new one.

Collet
A type of chuck or holding device for bits with a narrow range so that multiple collets are required for bits with different shank sizes. Collets are more precise and lighter weight than a chuck. On a router, 1/4", 3/8", and 1/2" collets are the most common. Generally a wrench is required to tighten or loosen a collet.

Compound Angle
An angle which is defined in two distinct planes. In the case of a mitered cut, one angle is formed looking at the piece from the top and the other looking at the piece from the side.

Dado
A recess or groove that is cut through a piece of wood or other material. A dado is commonly used as the insertion point for joining materials, often shelves, at right angles as in a box or cabinet carcase.

Direct Drive
In this type of tool the motor shaft is directly connected to the blade or bit. It is very often used to describe a common type of circular saw. The other type of circular saw drive is worm drive, or it's near cousin the hypoid drive, which uses a gearing system to deliver greater torque to the blade.

Drill Press
The drill press is a type of drill that is mounted on a stand or bolted to the floor or workbench. Start parts of a drill press consist of a base, column, table, spindle, and drill head. A set of handles on the head are used to move the spindle and chuck vertically downwards. The table can be adjusted up and down, usually by a rack and pinion, and then clamped in place. It may also be turned or rotated to allow the bit to enter at an angle. The advantages of using a drill press over a hand-held drill are less effort on the part of the operator, repeatable results for multiple work pieces, safety, and most importantly, accuracy.

Electric Brake
A feature in power tools which quickly stops the tool when it is turned off. Portable drills, circular saws and miter saws very often have electric brakes which stop the chuck or blade within a a couple of seconds rather than coasting to a stop. This results in a safer tool.

Ferrule
A metal ring used to hold a chisel or gouge tool in its handle. The tang of the tool extends into the handle and the ferrule compresses the top of the tool to keep the tang in place. It also protects the handle from splitting in the event of excessive pressure on the handle, usually caused by striking it with a mallet.

GFCI
Ground Fault Circuit Interrupter (GFCI or GFI) helps protect people from electircal shock. It does this by monitoring the current flowing from the hot wire to a device and returning via the neutral wire from the device. If there is an imbalance, as little as a few miliamps, it trips an internal circuit breaker. This imbalance could be caused by current flowing from a tool, through a person, to ground. GFCI's cannot protect against all kinds electrical shock. If a person held both the hot and neutral wires and was not grounded a GFCI would not detect an imblance and would not trip. GFCI protection is often found in special plugs and outlets and sometimes circuit breakers. The GFCI device will typically have have a 'test' and 'reset' button allowing the GFCI function to be tested.

Grit
The abrasive particles found on sand paper. The grit number describes how many particles fit into a square inch. A 220 grit sandpaper would have 220 abrasive particles per square inch, 600 grit would have 600 particles per square inch. The large the number, the smaller the particles and the finer the sandpaper.

Hardwood
This terms refers to the lumber from a specific group of tree species rather than the hardness of the wood. Wood from angiosperm or broad-leaved trees is called hardwood. These trees are largely deciduous, losing their leaves in the winter, although tropical hardwoods may keep their leaves year-round. The hardest of trees are in the hardwood group of species. Some of harder domestic species include oak, hickory, and maple, but tropical species like ipe and teak are even more dense. However, some of the most soft woods also come from hardwood species, examples including balsa and bass woods. Hardwood's relative hardness and wide variety of color and grain pattern make them useful in a wide variety of applications including furniture manufacture, paneling and millwork. Modern construction uses hardwood only selectively preferring less expensive softwoods for timbers and plywoods.

Hook And Loop
The generic term for Velcro (tm) style of fastening. This method is often used to attach sanding disks to 5-6" random orbit sanders. Hook & loop style sandpaper is simply pressed onto, and peeled of of the sander base when needed. (The sander base has the loops and the sandpaper is backed with hooks). This allows sandpaper to quickly be changed from one grit to another durning a project without damaging the sandpaper. The other common technique of fastening sandpaper to random orbit sanders are by PSA pads.

Hypoid
A particular type of helical or spiral gear. A hypoid gear is tapered allowing it have greater contact with the drive gear than a worm gear. It can be considered halfway between a straight-cut gear and a worm gear. Hypoid drives are often found in circular saws with similar advantages as the worm drive.

Induction Motor
This is a type of alternating current electric motor in which the power source is fed through a primary winding and induces a current in a secondary winding, with the parts arranged so that the resulting magnetic field causes a movable rotor to rotate with respect to a fixed stator.

Jacobs Taper
The Jacobs taper is most commonly used to fasten drill press chucks to an arbor. The Jacobs Taper has different dimensions than another common family of tapers, the Morse Taper. Better drill presses use an arbor with a Morse Taper on one side and a Jacobs Taper on the other. The Jacobs Taper fastens the arbor to the chuck and the Morse Taper secures the arbor to the machine. A very common Jacobs Taper ofthen found on floor standing drill presses is the JT33.

Kerf
The width of the saw cut determined by the blade and the set of the teeth. The kerf is generally wider than the saw blade itself because the teeth are flared out sideways (the "set") which keeps the blade from binding. Flush cut saws either have teeth with no set or a set on only one side so that they can cut flat against the work surface without creating scratches.

Kick Back
This refers to a work piece being ejected backwards by a cutting blade. It is essential to hold the piece down with the hand or a push-stick (if the blade is close to the fence) while it is in contact with the blade. Table saws usually offer some type of anti-kickback device to prevent this from occurring.

Laser Guide
A device that draws a laser line or point on a work piece to tell an operator where to expect a cut to be executed. In the case of miter saw, the laser line generated by the guide, draws a line on either one or both side of the expected saw blade kerf. In the case of a drill press laser guide, double lines form a cross-hair to indicate the bit's center.

LED
The Light Emitting Diode (LED) is a solid state light used in many portable power tools to light the work piece. LEDs are small, use little power, bright and immune to vibration.

Lithium Ion
Batteries made with lithium ion are the emerging choice for battery powered tools. The have greater energy densities than nickel cadmium (NiCad) or nickel metal hydride (NiMh) batteries making deliver the same power in a lighter package. Lithium ion batteries have no 'memory effect' and they self-discharge very slowly. However, they are expensive and require the most complex battery charging circuitry so that tools using them command a high price.

Miter Saw
A tool used to cut accurate angles or "miter cuts". Hand powered miter saws have largely been replaced by motorized models, although the manual miter saws continue to be used by picture framers. A motorized miter saw is also commonly called a chop saw or a drop saw. They are ubiquitous is shops and at work sites because of their ability to quickly and accurately cut angles in framing timber, molding, furniture pieces, and other parts in woodworking and construction applications. Miter saws excel at crosscutting material. The material they can handle is generally limited to the width of the blade unless they incorporate a sliding mechanism to allow the blade to move forward and backward. In some saws, the blade can be rotated in two planes to achieve compound angles.

Morse Taper
Taper shanks allow the accurately centered, press fit, installation of accessories into a taper mount. Taper mounts are found in many machines such as milling machines, lathes and drill presses. For example a drill press will have an arbor that have a slightly tapered shank which press fits into a tapered hole in the drill press. Drill presses often use this method to attach the arbor allowing it to be popped out and replaced by a diffent chuck or other attachments. A morse taper is the most common style of taper used in drill presses and lathes. It somes in various sizes. The #2 and #3 morse taper is the most common size found in home shops. Another popular taper is the Jacobs Taper (JT). Better drill presses have an arbor with a Morse Taper to connect the arbor to the press and a Jacobs Taper to attch the chuck to the arbor.

Nickel Cadmium
Batteries made with nickel cadmium have been around a long time and are tried and true, but they have lower energy densities than newer nickel metal hydride (NiMH) and lithium ion (Li-Ion) batteries. They are also more prone to the 'memory effect' if not discharged below about 60% before recharging. Nicads are the least expensive tool batteries and they have good low temperature performance and are fairly forgiving about deep discharges or over charging.

Nickel Metal Hydride
Batteries made with nickel metal hydride have better energy densities than batteries made with nickel cadmium (NiCad) but not the energy density of lithium ion batteries, the emerging choice for battery powered tools. They are less prone to 'memory effect' than NiCad batteries, but deep discharges may degrade their life.

Plunge
The ability of a tool begin a cut in the middle of a workpiece without pre-drilling a hole. For example a plunge router can be placed on a workpiece then lowered into the piece to a preset depth using it's base. Plunge cutting jigsaw blades have sharp edges on the tip to allow angling the running blade directly into the surface of a workpiece.

PSA
Pressure Sensitive Adhesive (PSA) refers to the peel-and-stick technique often used to fasten sandpaper to random orbit and disk sanders. The sanding disk is backed with peel and stick adhesive. The backing is peeled off the sandpaper and it is then stuck to the clean, flat sanding surface. Unlike hook and loop style fastening systems PSA sandpaper cannot be peeled off and reused over and over again. Once the sandpaper is peeled off of the sander the adhesive will have lost much of it's grip. However it provides a very strong bond between the sandpaper and the sanding pad and is used for nearly all larger disk sanders. Random orbit sanders also commonly used hook and loop style fastening to fasten sandpaper to the sander base.

Rabbet
A recess or groove that is cut into the edge of a piece of wood or other material. A rabbet is commonly used as the insertion point for joining materials at right angles as in a box or cabinet carcase. Outside of North America, a rabbet is also known as a rebate.

Router
A hand-held or table mounted tool that rotates cutters with different profiles at high speeds. It is used to rout out or remove material from a piece of wood or other material. Among their many uses, routers can be used to create dados, rabbets, cut profiles for moldings, and create beads and other edges.

RPM
Revolutions Per Minute (RPM) describes the rotational speed of a tool. Differing RPM's are used to cut different materials. For instance a low speed 150 RPM my be used by a drill press to drill through hard metals, where a higher speed 4000 RPM may be used to drill through soft woods. The combination of the bit or blade and the material to be worked will determine the best RPM for the job.

Sawfiler
This is the title of the person responsible for repairing and maintaining the large and expensive saws in a timber mill. The job requires a many years of training and a great deal of skill.

Self Feed
The ability of a tool to move itself into the material without external pressure. A common example is a self-feed drill bit which has a screw like point which screws into the wood pulling the bit into the material as it goes.

Shank
The part of a tool accessory, usually a bit or blade, that attaches to a collet or chuck. In the case of a router or drill bit, a collet or chuck holds the shank in place and drives the bit's rotation. The shank size for standard drill bits is generally the same size as the bit itself until bits become larger than 1/2". Shank sizes for routers bits are standarized at 1/4", 3/8", and 1/2".

Sidewinder
This term is often used describe direct drive circular saws. In this type of saw the motor shaft is directly connected to the blade. The other type of circular saw drive is worm drive, or it's near cousin the hypoid drive, which uses a gearing system to deliver greater torque to the blade.

Soft Start
A feature power tools which slowly speeds up the tool to prevent it from jerking harshly when it is turned on. Probably the most common example of a tool that uses this feature is a router.

Softwood
This terms refers to the lumber from a specific group of tree species rather than the hardness of the wood. Wood from conifers including yew, fir, spruce, pine, douglas-fir, cypress, and redwood are softwoods. While these species produce wood that is, on average, less dense than hardwoods, many softwood species (yew for example) are harder than other hardwood species. Many softwood species are fast-growing with long, straight trunks so that they represent the majority of construction lumber including dimensional timbers, plywoods, and manufactured products like MDF.

Spindle Lock
A mechanism on a tool which locks the spindle without requiring a tool. This facilitates changing the blade or bit by reducing the tools needed.

Table Saw
The table saw or sawbench is one of the most common and versatile stationary woodworking tools. A circular saw blade, mounted to an arbor, is generally driven by an electric motor. The motor may be connected directly, by gears, or most commonly, by one or more belts. The blade of a table saw protrudes through the table surface and the depth of cut is determined by raising and lowering the saw blade. Most modern saws allow the arbor to be tilted providing for angled cuts.

Tang
Part of a blade, chisel, or carving gauge that extends into the handle of the tool. It is often, although not always, held in place by a ring, or ferrule.

TEFC
Totally Enclosed, Fan Cooled. Typically this means the motor is dust tight with a small fan mounted on the shaft (inside the housing) which pulls air over cooling fins of the motor keeping the motor cool. This protects the motor from typical hazards in a small shop environment. Note - These motors are not waterproof or designed to operate in hazardous environments.

Three-Phase
Power plants generate power in three phases that are offset by 120 degrees from each other. Industrial shops are wired to use three-phase power while homes have only single-phase power. Motors using three-phase power are inherently simpler, more reliable, and have higher starting torque than single phase equivalents making them ideal for industrial applications.

Torque
It is a force that produces or tries to produce rotation. Informally, it is "rotational force" or "angular force". In machinery, it is the measured ability of a rotating element, as of a gear or shaft. The torque rating of a tool is a standarized method of determining how much torque the tool delivered at maximum power.

Torque Rating
Torque is a force that produces or tries to produce rotation. Informally, it is "rotational force" or "angular force". In machinery, it is the measured ability of a rotating element, as of a gear or shaft. The torque rating of a tool is a standardized method of determining how much rotational force the tool delivered at maximum power. The process to determine drill ratings is a standard in the industry accomplished by mounting the drill to a piece of test equipment and then running the drill at full power.

Voltage
The difference of electrical potential between two points of an electrical circuit. Voltage measures the potential energy of an electric field to cause an electric current. The amount of power used by a tool is the product of the amperage (or current) and the voltage (P=VI). At higher voltages, tools can operate at lower amperages which reduces the requirement for larger wires. Doubling the voltage delivers allows the amperage to be reduced by one-half.

Worm Drive
A gearing system which allows very high torque to be transmitted. It does this by using a cylindrically shaped, spiral grooved gear to reduce the rotation speed of a motor. Worm drive and their near cousin the hypoid drive are very tough and durable. Often found on circular saws, worm drives allow the blade to be placed to the left of the motor rather than the right. This can be more comforatable for right handers to use, though worm drive saws tend to be heavier.