Band saw

Also called: bandsaw

A band saw is a saw made from a single thin strip of steel, its edge cut into teeth, welded into a loop and run over two large wheels so the blade travels always in one direction, cutting continuously, rather than moving back and forth. Audels (1923) put it plainly: a band saw "may be described as a thin strip of tempered steel with teeth cut in it and made endless to run around two pulleys."

How it cuts, and how that differs from other saws

Because the blade forms a closed loop running down through the table, a band saw cuts continuously, with no return stroke wasted the way a reciprocating saw's blade wastes half its motion moving back before the next cutting stroke. Audels (1923) counted this steady, continuous action as the band saw's chief advantage over reciprocating saws, though he noted that large mills still kept gangs of reciprocating saws at work, since such a gang could cut as many as thirty boards at once. He also pointed out that a band saw blade's thinness, compared with a circular saw's, wastes less wood as sawdust with every cut, a saving that adds up over a long run of work. A band saw blade also behaves differently from a circular saw's in use: it cannot kick the workpiece back at the operator, the sudden violent throw that happens when a spinning circular blade catches and ejects the wood. Bird (2004) treats this as what makes the band saw well suited to ripping heavy, warped stock that would otherwise bind and jam in a table saw.

What it is good for

Ripping heavy or warped boards, as above, is one strength. The band saw also resaws lumber, slicing a thick board down its width into two or more thinner boards, and cuts curves and irregular shapes that would defeat a saw with a straight, rigid blade. It is a natural choice, alongside the jigsaw, for cutting an undulating curve marked out freehand or the outside contour of a shape from a template, and for cutting curved structural parts such as the rib of an arch frame once its outline has been marked. Where no band saw is to hand on site, a portable jigsaw can do the same job. The machine can also be pressed into joinery, cutting finger joints, an interlocking row of squared fingers cut into the ends of two boards, with the help of a fence and a spacer set to the width of the blade. One job a band saw cannot do is piercing, cutting a hole in the middle of a board without entering from an edge, because its blade is a closed loop that cannot be threaded through a hole drilled first. Jones (1920) made this comparison directly: most work a band saw performs can also be done on a fretsaw, a fine saw that cuts on the downstroke only, though much more slowly, but for piercing and similar inside cutting the fretsaw has no equal, because unlike the band saw's continuous loop, its blade can be released and rethreaded through the work.

Setting up and blade care

A band saw needs its wheels aligned before use, and its blade correctly tracked, tensioned and sized to the work in hand for safe, effective cutting. Band saw blades are joined into a loop at a brazed seam: Grimshaw (1880) gave a rule for the bevel of this joint, that the bevelled scarf on each side should be as long as the gap between two teeth. The gap in front of each tooth is called the gullet; where a properly shaped rounded triangular file was not to hand, Grimshaw noted that an ordinary rat-tail file could be used to round out the gullets instead. Grimshaw also pointed to the Newberry band saw of 1808 as an early example of the machine.