Band Saw

The band saw is a cutting machine in which a thin, long blade — welded at both ends into a loop — is stretched and driven between two wheels. It's not counted among the pipe workshop's mandatory machines; drilling and shaping can be carried out without one. Even so, it's regarded as one of the first "convenience" tools that speed up the work: it takes the excess off a square briar block in seconds and noticeably cuts down what's left for sanding or filing. For where cutting fits in the production flow, see the how a pipe is made entry.

Working Principle and Brief History

The machine's idea isn't new: William Newberry was granted a patent in England in 1809 for the concept of cutting with an endless band blade. But the steel of the day couldn't bear the strain, blades kept snapping, and the design remained on paper for a long time. The step that solved the problem came in France in 1846, when Anne Paulin Crepin's welding method was transferred to A. Perin & Company in Paris, and a usable blade emerged along with advances in alloy and tempering technique. America's first band saw patent is recorded as having been granted in 1836 to Benjamin Barker of Ellsworth, Maine.

Blade Width and Turning Radius

On a band saw, the decisive measurement isn't the machine's power but the blade's width. The narrower the blade, the tighter a curve it can follow; as it widens, it becomes more stable in straight cuts and more reluctant to take a curve. Manufacturers' published minimum-radius charts don't line up exactly; the figures given for a 3/8-inch blade range roughly from one to one and a half inches. In pipe making, this width is considered a suitable middle ground: it's enough to take the corners off a block and rough out the outline, and for tighter curves the work is left to sanding anyway. The general rule is to use the widest blade suited to the cut at hand.

The cleanness of the cut depends on setup as much as on the blade. General woodworking practice holds that correctly tensioning the blade, setting the upper and lower guides close to the blade, lowering the guide to the workpiece, and squaring the table keep the cut from drifting off the line. On an unadjusted machine the blade wanders sideways and causes a loss in the block that's hard to make up for.

Place in the Workshop

The band saw's job is limited to rough cutting; the final surface never comes off the saw. Once the block is cut, the work moves on to tools like a belt sander or a lathe. Some makers prefer to cut after drilling the hole, because a square block mounts more securely on a drill press; see the shaping before drilling entry for this preference. Grain direction also matters during cutting: how much is taken from which face of the block directly determines the grain pattern that will show on the outside.

Two points stand out for safety. At least two of the blade's teeth should be in contact with the workpiece at all times; otherwise the teeth can catch and strip. Second is the fine dust briar leaves behind — dust extraction and eye protection are needed at this machine too.