Band saw

A band saw is a saw that can be used for woodworking, metal working, and a variety of other materials. It gets its name from its blade, consisting of a narrow band of toothed metal. This band rides on two wheels in the same vertical plane with a space between them. Band saws are particularly useful for cutting irregular shapes. The radius of a curve that can be cut on a particular saw is determined by the width of the band.

Metal Cutting Band Saws

When cutting metals, special band saws are required that include coolant pumps which provide a constant flow of liquid coolant over the blade. The coolant keeps blades cool and clean, adding blade life. Metal cutting band saws are available in vertical and horizontal designs. These units range from manual to semi-automatic and even automatic controls.

Large band saws

Timber mills use very large band saws for ripping lumber; they are preferred over circular saws for ripping because of their smaller kerf (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). Band saws 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 after every four hours of use. Sawfilers or sawdoctors are the craftsmen responsible for this work.

The shape of the tooth gullet is highly optimized and designed by the sawyer 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 with a grinding wheel. The sawfiler will need to maintain the grinding wheel's profile with periodic dressing of the wheel.

Head saws

Head saws are large band saws that make the initial cuts in a log. They generally have a two to three 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.

In the earlier years of wood production, Head Saws would be used to cut all log diameters generally up to approximately 72". Today, the Head saws may be more so used for cutting log diameters of 16" to 72" in diameter depending upon the type of Band Mill the saws are mounted on. More optimized machines now cut the smaller diameters since they are far more efficient and can provide greater production.

Dependent upon the log diameter, Head Saws can cut a log at speeds ranging from 1 to 300 feet per minute. Generally, Log Carriage speeds are adjustable for optimal performance.

Resaws

A resaw is a large bandsaw optimized for resawing. This involves cutting timber along the grain to reduce larger sections into smaller sections or veneers. Resawing veneers requires a wide blade - commonly 2" to 3" (52 - 78 mm) - with a small kerf to minimize waste. Resaw blades of up to 1" (26 mm) may be fitted to a standard bandsaw.

Timber mills use larger resaws to rip large planks into smaller sizes. A typical mill sized resaw is eight inches wide and made with 16 gauge steel. Resaws can be identified by their flat back, as opposed to headsaws and doublecuts which don't have a flat back.

Double cut saws

Double cut saws have cutting teeth on both sides (see sawfiler for a picture of a very small double cut). They are generally very large, similar in size to a head saw.

References

Mark Duginske (1989). The Bandsaw Handbook. Sterling Publishing. ISBN 0-8069-6398-0

External links

Manufacturers

Woodworking machines | Metalworking | Saws

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