Band saw - AbsoluteAstronomy.com

A bandsaw is a power tool

Power tool

A power tool is a tool that is actuated by an additional power source and mechanism other than the solely manual labour used with hand tools. The most common types of power tools use electric motors. Internal combustion engines and compressed air are also commonly used...

which uses a blade

Blade

A blade is that portion of a tool, weapon, or machine with a cutting edge and/or a pointed tip that is designed to cut and/or puncture, stab, slash, chop, slice, thrust, or scrape animate or inanimate surfaces or materials...

consisting of a continuous band of metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

with teeth along one edge to cut

Cutting

Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the application of an acutely directed force. An implement commonly used for cutting is the knife or in medical cases the scalpel...

various workpieces. The band usually rides on two wheels rotating in the same plane, although some small bandsaws have three wheels. Bandsawing produces uniform cutting action as a result of an evenly distributed tooth load. Bandsaws are used for woodworking

Woodworking

Woodworking is the process of building, making or carving something using wood.-History:Along with stone, mud, and animal parts, wood was one of the first materials worked by early humans. Microwear analysis of the Mousterian stone tools used by the Neanderthals show that many were used to work wood...

, metalworking

Metalworking

Metalworking is the process of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewelry. It therefore includes a correspondingly wide range of skills,...

, 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.

Meat cutting

Saws for cutting meat

Meat

Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...

are typically of all stainless steel

Stainless steel

In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....

construction with easy to clean features. The blades either have fine teeth with heat treated tips, or have plain or scalloped knife edges.

Metal cutting

Brushes or brushwheels are sometimes used to remove chips from the blade as it exits the material. Bandsaws are available in vertical and horizontal designs. Band speeds range from 40 feet (12 meters) per minute to 5,000 feet (1,500 meters) per minute. Specialized bandsaws are built for friction cutting of hard metals and may run band speeds to 15,000 feet per minute.

Horizontal bandsaws hold the workpiece stationary while the blade swings down through the cut. This may employ a gravity feed alone or the rate of descent may be controlled by a hydraulic cylinder

Hydraulic cylinder

A Hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in engineering vehicles.- Operation :...

bleeding

Bleeding

Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...

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.

A vertical bandsaw has a stationary blade while the workpiece is moved against the blade manually or with a power assist mechanism. This type of metal-cutting bandsaw is often equipped with a built-in blade welder. This not only allows the operator to repair broken blades quickly, but also allows for the blade to be purposely cut, routed through the center of a part, and re-welded in order to make interior cuts.

Advancements have also been made in the bandsaw blades used to cut metals. The development of new tooth geometries and tooth pitches have produced increased production rates and greater blade life. New materials and processes such as M51 steel

Tool steel

Tool steel refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools. Their suitability comes from their distinctive hardness, resistance to abrasion, their ability to hold a cutting edge, and/or their resistance to deformation at elevated temperatures...

and the cryogenic treatment

Cryogenic treatment

A cryogenic treatment is the process of treating workpieces to cryogenic temperatures to remove residual stresses and improve wear resistance on steels....

of blades have produced results that were thought impossible just a few years ago. New machines have been developed to automate the welding

Welding

Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

process of bandsaw 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 bandsaws for ripping

Rip cut

In woodworking, a rip cut is a cut made parallel to the wood grain. Rip cuts are commonly made with a table saw, but other types of saws can also be used, including hand rip saws, radial arm saws and band saws...

lumber

Lumber

Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....

; they are preferred over circular saw

Circular saw

The circular saw is a machine using a toothed metal cutting disc or blade. The term is also loosely used for the blade itself. The blade is a tool for cutting wood or other materials and may be hand-held or table-mounted. It can also be used to make narrow slots...

s for ripping because they can accommodate large-diameter timber and because of their smaller kerf

Kerf

Kerf and similar can mean:* kerf, the width of a cut* Kerf, a poetry collection by Peter Sanger* Kerala E.N.T. Research Foundation , a hospital at Kollam in Kerala in India...

(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). Bandsaws 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. Sawfiler

Sawfiler

A saw filer or saw doctor 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....

s or sawdoctors are the craftsmen responsible for this work.

The shape of the tooth gullet is highly optimized and designed by the sawyer

Sawyer

Sawyer is an occupational term referring to someone who saws wood. One such job was the now-archaic occupation of someone who cut lumber to length for the consumer market, a task now done by end users or at lumber and home improvement stores...

and sawfiler. 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 sawfiler will need to maintain the grinding wheel's profile with periodic dressing of the wheel.

Head saws

Head saws are large bandsaws that make the initial cuts in a log. They generally have a 2 inch 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 bandsaw optimized for cutting timber along the grain to reduce larger sections into smaller sections or veneers

Wood veneer

In woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...

. Resawing veneers requires a wide blade - commonly 2 inch - with a small kerf to minimize waste. Resaw blades of up to 1 in (2.5 cm) may be fitted to a standard bandsaw.

Double cut saws

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

Feed mechanisms

Gravity feed saws fall under their own weight. Sometimes the saw has a movable weight which allows the cutting force to be adjusted. Often times this type of saw is equipped with a hydraulic speed control valve. This does not force the blade downwards, but rather limits the speed at which the saw can cut preventing excessive feed on thin or soft parts. This design is common in small saws.
Hydraulic feed saws use a positive pressure hydraulic piston to advance the saw through the work at variable pressure and rate. Common in production saws.
Screw feed employ a leadscrew to move the saw.

Fall mechanisms

Pivot saws hinge in an arc as they advance through the work.
Single column saws have a large diameter column that the entire saw rides up and down on, very similar to a drill press.
Dual column saws have a pair of large columns, one on either side of the work, for very high rigidity and precision. The dual column setup is unable to make use of a miter base due to inherent design. Dual column saws are the largest variety of machine bandsaws encountered, to the point where some make use of a rotary table and X axis to perform complex cutting.

Automated saws

Automatic bandsaws feature preset feed rate, return, fall, part feeding, and part clamping. These are used in production environments where having a machine operator per saw is not practical. One operator can feed and unload many automatic saws.

Some automatic saws rely on numerical control

Numerical control

Numerical control refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone...

to not only cut faster, but to be more precise and perform more complex miter cuts.

Common tooth forms

Precision blade gives accurate cuts with a smooth finish.
Buttress blade provides faster cutting and large chip loads.
Claw tooth blade gives additional clearance for fast cuts and soft material.

At least two teeth must be in contact with the workpiece at all times to avoid stripping off the teeth.