Sawing

Also called: ripping, crosscutting

Sawing is cutting wood by drawing a row of teeth through it until the blade parts the fibres clean through. Almost all of it comes down to two strokes: ripping, which cuts along the length of the grain, and crosscutting, which cuts across it, and each needs teeth shaped differently.

Ripping and crosscutting

A ripsaw is defined by cutting along the direction of the wood's grain, working with the fibres rather than across them; a crosscut saw works across them instead, and saw blades in general split broadly into these two kinds, with the teeth shaped one way for ripping and another for crosscutting. A rip cut works best driven at roughly forty-five degrees to the material; as Audels (1923) explained, "the thrust of the saw should be on an angle of about 45° to the material being cut; this makes a shearing cut". Ripping thoroughly dry lumber goes better with an extra-thin backsaw, a fine, backed handsaw, that needs no set, the outward bend given to alternate teeth to clear the blade in the cut. If a large knot turns up while ripping, it can be worth switching to a crosscut saw until past it. Used the other way round, a saw meant for ripping can still crosscut, but it leaves end grain, the surface exposed where the fibres are cut straight across, badly torn, and crosscutting with a ripsaw rarely gives a good result. Saw makers have long marketed dual-purpose blades even so: Disston (1923) described its own saw as: "The most efiicient saw ever made for double duty work—that is, both cros-cut and rip sawing with the same tool." Today a combination blade ground to a compromise pattern rips and crosscuts well enough to spare frequent blade changes. When crosscutting a hardwood, the saw is held at a shallow angle to the wood's face. Starting a crosscut with a hand saw or panel saw, a saw with a broad blade and no stiffening back, begins the same way as starting a rip cut. Crosscut sawing itself is graded into three classes, according to how much the accuracy of the cut matters to the job. Even where a saw cut lands close to the marked angle, high-class joinery work still needs the sawn end planed afterwards, so that a glued joint will close tightly.

Saws for particular jobs

One traditional saw pattern cuts along and across the grain alike and is prized particularly for cutting tenons, while another all-purpose pattern handles light ripping and crosscutting well enough to spare keeping two separate saws for heavy work. A panel saw generally comes from the factory set up for crosscutting rather than ripping, especially where it is aimed at carpenters cutting damp softwood. A blade filed finer than a typical ripsaw's teeth can speed up ripping while still crosscutting reasonably well. In one comparison of his own, Frid (1979) found a frame saw, a saw held under tension in a wooden frame, to outpace a panel saw at both ripping and crosscutting. On the power-saw side, a band saw will rip heavy, bowed timber without binding, where a table saw would jam on the same piece, and some crosscut saws handle repetitive, accurate crosscuts on long stock such as moulding better than a table saw does. In furniture-industry work beyond a table saw's capacity, certain large saws are kept mainly to crosscut random-width plank and to rip oversized plywood. Fine-toothed band-saw blades are generally the ones reached for when smoothing cuts, crosscutting, detail work, diagonal cuts or cutting across mixed grain are needed. A thinner blade profile behind the teeth is what lets a hollow-ground blade, one ground thinner just behind the cutting edge, leave a fine crosscut finish. On a power saw, a compound cut tilts the blade away from vertical relative to the saw's base plate, while a single-bevel cut keeps the blade upright against it.

Marking and finishing the cut

Squaring frame parts and panels to size, by ripping and crosscutting them, is work done before assembly starts in frame-and-panel construction. Handsawn work is commonly cut resting on a dedicated sawing board, and a cut can also be run straight through into a sacrificial board placed beneath the work. Pointing a finger toward the intended cut line helps steer the saw, and the cut itself should track the waste side of a clearly marked pencil line. Near the finish of a cut, slowing the saw and supporting the falling offcut by hand avoids a rough break; one hand-sawing tradition outside the West instead props the work up on either face along the kerf, the slot the saw leaves as it cuts, stopping the falling offcut from tearing loose.