Biscuit Joiner

Biscuit Joiner

A biscuit joiner (or sometimes plate joiner) is a woodworking tool used to join two pieces of wood together. A biscuit joiner uses a small circular saw blade to cut a crescent-shaped hole (called the mouth) in the opposite edges of two pieces of wood or wood composite panels. An oval-shaped, highly dried and compressed wooden biscuit (beech or particle wood) is covered with glue, or glue is applied in the slot. The biscuit is immediately placed in the slot, and the two boards are clamped together. The wet glue expands the biscuit, further improving the bond.

Biscuit Joiner


The biscuit joining system was invented in 1956 in Liestal, Switzerland by Hermann Steiner. Steiner opened his carpenter’s shop in 1944, and, in the middle of the 1950s, while looking for a simple means of joining the recently introduced chipboard, invented (almost by accident) the now world-famous Lamello joining system. In the succeeding years there followed further developments such as the circular saw and the first stationary biscuit (plate) joining machine in 1956 followed by the first portable biscuit joiner for Lamello grooves in 1968. In 1969 the family operation was incorporated by the name of Lamello AG. Lamello continues to manufacture very high-end biscuit joiners such as the Lamello Top 20.

Several other companies such as Porter Cable, Dewalt, and Makita also manufacture compatible biscuit joiners, including some models with interchangeable blades, enabling the user to cut both 4″ and 2″ biscuit slots.


Biscuits are predominantly used in joining sheet goods such as plywood, particle board and medium-density fibreboard. They are sometimes used with solid wood, replacing mortise and tenon joints as they are easier to make and almost as strong. They are also used to align pieces of wood when joined edge-to-edge in making wider panels. It is important to use the same face when cutting the slots, so the boards are perfectly flush.

Biscuits are also used to align edges of workpieces, such as when forming a 90 degree angle between workpieces. The biscuit provides a quick means of getting a perfectly flush joint, while at the same time reinforcing the joint.

Typically, the machine will have an adjustable fence, so it can be set on an angle for joining mitered pieces.

Also, there are other types of specialty biscuits available, from metal connectors, used for removable panels, to hinges, making these portable machines even more flexible.


The workpieces are brought together and the user marks the location for the biscuits. Precise measurement is not required, as the biscuits are hidden when the pieces are assembled, so a quick pencil stroke that marks both pieces where they align is all that is required. The parts are separated and the machine is used to cut the slots in each piece. The machine has reference marks on the center line of the blade for easy alignment to the marks on the materials being joined.

The body of the machine with the blade is spring-loaded and in the normal position the blade is retracted. The operator aligns the machine and uses a firm pressure to push the body forward against the base plate to make the cut. The waste material is blown out of the slot on the right of the base plate.

Because the slots are slightly longer than the biscuits, it is still possible to slide the panels sideways after the joint is assembled (before the glue sets). This fact makes the biscuit joiner easy to use, because it does not require extreme accuracy or jigs to achieve perfect joints.

Belt Sander

Belt Sander

A belt sander is a sander used in shaping and finishing wood and other materials. It consists of an electric motor that turns a pair of drums on which a continuous loop of sandpaper is mounted. Belt sanders may be handheld and moved over the material, or stationary (fixed), where the material is moved to the sanding belt. Stationary belt sanders are sometimes mounted on a work bench, in which case they are called bench sanders. Stationary belt sanders are often combined with a disc sander.

belt sander

Belt sanders can have a very aggressive action on wood and are normally used only for the beginning stages of the sanding process, or used to rapidly remove material. Sometimes they are also used for removing paints or finishes from wood. Fitted with fine grit sand paper, a belt sander can be used to achieve a completely smooth surface.

Stationary belt sanders are used for removing non-ferrous metals, such as aluminum. Non-ferrous metals tend to clog grinding wheels, quickly making them useless for grinding soft metals. Because the small grooves in the sandpaper are opened up as they go around the arc of the drive wheel, belt sanders are less prone to clogging.

Belt sanders can vary in size from the small handheld unit shown in the illustration to units wide enough to sand a full 1.2 by 2.5 m (4-by-8 foot sheet) of plywood in a manufacturing plant. Some belt sanders can be as large as 1.2 by 0.7 metres (3 ft 11 in × 2 ft 4 in).

Sanding wood produces a large amount of sawdust. Therefore, belt sanders employed in woodworking are usually equipped with some type of dust collection system. It may be as simple as a cloth filter bag attached to a portable sander or a large vacuum system to suck dust particles away into a central collector.

Taut-belt sanders allow for adjusting the angle of the idler drum to keep the belt centered. Slack-belt sanding is commonly used in the manufacturing process of guitars and other medium-sized wooden objects. It employs a long sanding belt which runs slackly over the object. The machinist then exerts pressure to it to sand down specific areas.



A bandsaw uses a blade consisting of a continuous band of toothed metal rotating on opposing 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 connected by a belt or chain rotating in the same plane, one of which is powered, although some may have three or four to distribute the load.



The idea of the band saw dates back to at least 1809, when William Newberry received a British patent for the idea, but band saws remained impractical largely because of the inability to produce accurate and durable blades using the technology of the day. Constant flexing of the blade over the wheels caused either the material or the joint welding it into a loop to fail.

Nearly 40 years passed before Frenchwoman Anne Paulin Crepin devised a welding technique overcoming this hurdle. She applied for a patent in 1846, and soon afterward sold the right to employ it to manufacturer A. Perin & Company of Paris. Combining this method with new steel alloys and advanced tempering techniques allowed Perin to create the first modern band saw blade.

The first American band saw patent was granted to Benjamin Barker of Ellsworth, Maine, in January of 1836. The first factory produced and commercially available band saw in the U.S. was by a design of Paul Prybil.

Power hacksaws (with reciprocating blades) were once common in the metalworking industries, but bandsaws and cold saws have mostly displaced them.


Angle Grinder

Angle Grinder

An angle grinder, also known as a side grinder or disc grinder, is a handheld power tool used for cutting, grinding and polishing.

Angle grinders can be powered by an electric motor, petrol engine or compressed air. The motor drives a geared head at a right-angle on which is mounted an abrasive disc or a thinner cut-off disc, either of which can be replaced when worn. Angle grinders typically have an adjustable guard and a side-handle for two-handed operation. Certain angle grinders, depending on their speed range, can be used as sanders, employing a sanding disc with a backing pad or disc. The backing system is typically made of hard plastic, phenolic resin, or medium-hard rubber depending on the amount of flexibility desired.



Angle grinders may be used for removing excess material from a piece. There are many different kinds of discs that are used for various materials and tasks, such as cut-off discs (diamond blade), abrasive grinding discs, grinding stones, sanding discs, wire brush wheels and polishing pads. The angle grinder has large bearings to counter side forces generated during cutting, unlike a power drill, where the force is axial.

Angle grinders are widely used in metalworking and construction, as well as in emergency rescues. They are commonly found in workshops, service garages and auto body repair shops. There is a large variety of angle grinders to choose from when trying to find the right one for the job. The most important factors in choosing the right grinder are the disc size and how powerful the motor is. Other factors include power source (pneumatic or electric), rpm, and arbor size. Generally disc size and power increase together. Disc size is usually measured in inches or millimetres. Common disc sizes for angle grinders in the U.S.A. include 4, 4.5, 5, 6, 7, 9 and 12 inches. Discs for pneumatic grinders also come much smaller. Pneumatic grinders are generally used for lighter duty jobs where more precision is required. This is likely because pneumatic grinders can be small and light yet remain powerful, because they do not contain heavy copper motor windings, while it is harder for an electric grinder to maintain adequate power with smaller size. Electric grinders are more commonly used for larger, heavy duty jobs. However, there are also small electric grinders and large pneumatic grinders.
Through a sound pressure level and vibrations study conducted by the National Institute for Occupational Safety and Health, grinders under an unloaded condition ranged from 91 to 103 dBA. In addition, angle grinders produce sparks when cutting ferrous metals. They also produce shards cutting other materials. The blades themselves may also break. This is a great hazard to the face and eyes especially, as well as other parts of the body, and as such, a full face shield and other protective clothing must be worn. Angle grinders should never be used without their guard or handle attached; they are there as a necessary precaution for safety. All work should be securely clamped or held firmly in a vice.

Alligator Shear

An alligator shear, historically known as a lever shear and sometimes as a crocodile shear, is a metal-cutting shear with a hinged jaw, powered by a flywheel or hydraulic cylinder. Alligator shears are generally set up as stand-alone shears; however, there are types for excavators. The jaw size can range from 4 to 36 in (100 to 910 mm) long. They are generally used to cut steel members, such as rebar, pipe, angle iron or I-beams.

Alligator shear


Older alligator shears were powered by a flywheel. These shears ran continuously, which posed a safety hazard. Now alligator shears are hydraulically actuated. When actuated, the piston arm extends and slowly closes the upper jaw of the alligator shear, which passes alongside the bed or lower jaw of the shear to perform the cut.


Alligator shears are used for cutting long metal stock or scrap, generally where accuracy is not an important consideration, and the size or shape of the material makes other cutting or shearing options impractical- often the only other cutting option is cutting with a torch. Alligator shears are often used in conjunction with large metal shredders in the metal recycling industry, to ‘clean’ or prepare scrap for shredding by removing unwanted fittings or other parts the shredder will not accept.


The safety requirements for other powered metalworking shears are contained in ANSI B11.4, but alligator shears are specifically exempted from that standard. Federal OSHA and various state OSHA programs have requirements for guarding alligator shears, and newly manufactured alligator shears are provided with guards that adjust to the size of the stock or scrap being cut. The purpose of this guard, however, is to prevent pieces of metal from being ejected during cutting. Such a guard also prevents inadvertent exposure of the operator’s hands, but does not conform to more stringent ‘point of operation’ guarding requirements.

In an interpretive letter dated June 24, 1981, Federal OSHA discussed the guarding dilemma presented by the alligator shear.

In instances where the shear is exclusively used for routine cuts on standardized stock, safeguarding of the point of operation is definable. In other instances, the operator is safeguarded from exposure to the point of operation by the physical size and configuration of the material being cut.

These practical considerations for guarding are not exclusive to alligator shears. A much more common type of equipment, the press brake, also requires point of operation guarding when used with standardized stock, but not with large-dimension stock.

Air compressor – Applications

Air compressors have many uses, including: supplying high-pressure clean air to fill gas cylinders, supplying moderate-pressure clean air to a submerged surface supplied diver, supplying moderate-pressure clean air for driving some office and school building pneumatic HVAC control system valves, supplying a large amount of moderate-pressure air to power pneumatic tools, such as jackhammers, for filling tires, and to produce large volumes of moderate-pressure air for large-scale industrial processes (such as oxidation for petroleum coking or cement plant bag house purge systems).

Most air compressors either are reciprocating piston type, rotary vane or rotary screw. Centrifugal compressors are common in very large applications. There are two main types of air compressor’s pumps: oil-lubed and oil-less. The oil-less system has more technical development, but is more expensive, louder and lasts for less time than oil-lubed pumps. The oil-less system also delivers air of better quality.

The most common types of air compressors are: electric or gas/diesel powered compressors. The power of a compressor is measured in HP (Horsepower) and CFM (cubic feet of air per minute). The gallon size of the tank tells you how much compressed air “in reserve” is available. Gas/diesel powered compressors are widely used in remote areas with problematic access to electricity. They are noisy and require ventilation for exhaust gases. Electric powered compressors are widely used in production, workshops and garages with permanent access to electricity. Common workshop/garage compressors are 110-120 Volt or 230-240 Volt. Compressor tank shapes are: “pancake”, “twin tank”, “horizontal”, and “vertical”. Depending on a size and purpose compressors can be stationary or portable.

Air compressor

An air compressor is a device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces more and more air into a storage tank, increasing the pressure. When tank pressure reaches its upper limit the air compressor shuts off. The compressed air, then, is held in the tank until called into use. The energy contained in the compressed air can be used for a variety of applications, utilizing the kinetic energy of the air as it is released and the tank depressurizes. When tank pressure reaches its lower limit, the air compressor turns on again and re-pressurizes the tank.

air compresor

There are numerous methods of air compression, divided into either positive-displacement or roto-dynamic types.
Positive displacement

Positive-displacement compressors work by forcing air into a chamber whose volume is decreased to compress the air. Common types of positive displacement compressors are:-

Piston-type: air compressors use this principle by pumping air into an air chamber through the use of the constant motion of pistons. They use one-way valves to guide air into a cylinder chamber, where the air is compressed.
Rotary screw compressors: use positive-displacement compression by matching two helical screws that, when turned, guide air into a chamber, whose volume is decreased as the screws turn.
Vane compressors: use a slotted rotor with varied blade placement to guide air into a chamber and compress the volume. A type of compressor that delivers a fixed volume of air at high pressures.

Dynamic Displacement

Dynamic displacement air compressors include centrifugal compressors and axial compressors. In these types, a rotating component imparts its kinetic energy to the air which is eventually converted into pressure energy. These use centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air, which pressurizes it.