Assorted crosscut saw tooth patterns.
CROSSCUT SAW MANUAL
Reprinted from Crosscut Saw Manual by Warren Miller (available from the Superintendent of Documents, U.S. Government Printing Office).
The two-man crosscut saw was known by the Romans, but not till the middle of the 15th century did the tool come into fairly common use in Europe. Records exist of the crosscut being used for cutting logs in the United States between 1635 and 1681. About 1880, Pennsylvania lumbermen began felling trees with the crosscut. Before that time all trees had been ax-felled and crosscut into lengths.
Until the 15th century, the two-man crosscut saw was of a plain tooth pattern. The M tooth pattern seems to have been developed and used in south Germany in the 1400's. Even as late as 1900 most of the European crosscuts still used the plain tooth pattern with only a few exceptions. Not until fairly recently was the saw with a raker or "drag" developed.
In the case of plain, M, and Great American tooth patterns, each tooth both cuts the wood and clears out the shavings. In the case of the champion, lance, and perforated-lance tooth, however, cutter teeth cut the wood fibers and the rakers remove the scored wood from the newly-sawn cut.
By the time crosscut use was at its peak, a large number of tooth patterns had been developed, each presumably suited to a particular set of conditions.
Crosscut saws can be divided into two types: two-man and one-man. Generally speaking, a one-man saw is shorter, but its defining characteristic is that it is asymmetric. Both types of crosscuts can be used by either one or two persons.
One-man crosscuts have been made in lengths from 3 to 6 feet. Two-man saws were produced in lengths from 4 to 12 feet for the Pacific Northwest, and 16 feet for the California redwoods. If a longer saw was needed, two shorter blades were sometimes brazed together.
There are two basic saw patterns for the two-man saw: the felling type for felling trees and the bucking pattern for cutting up trees once they are on the ground. Each has characteristics suited to its use.
The felling saw has a concave back and is relatively light and flexible. It is light so that less effort is needed to move it back and forth when felling a tree. It is flexible to conform to the arc a sawyer's arms take when sawing, and narrow tooth-to-back, enabling the sawyer to place a wedge in the cut behind the saw sooner than with a wide saw.
The bucking saw has a straight back. It is much thicker tooth-to-back than the felling saw, so it is heavier and stiffer. A bucking saw traditionally is run by one person, and its stiffness helps prevent buckling on the push stroke. The more weight put on a saw, the faster it will cut, so the weight of a bucking saw is an asset.
The teeth of nearly all crosscut saws lie on the arc of a circle. The result is an easier and faster cutting tool than a straight saw. A circular contour is much simpler to maintain than a curve of any other shape.
There are three ways that the sides of a saw are finished (ground) when manufactured. Each affects the thickness of the saw in a particular way. These are: flat, straight taper, and crescent taper.
A flat -ground blade is one whose thickness is the same everywhere. A taper-ground blade is thicker on its toothed edge than on its back edge, and has an advantage over a flat-ground implement: It is not as likely to bind in a cut, especially if the kerf is closing behind the saw (as will happen, if the wood being cut is under compression). Also, a taper-ground blade requires less set than one that is flat-ground.
The difference between the straight taper and crescent taper is that the lines of equi-thickness for the former are straight and those for the latter are concentric to the circle of the saw. This means that the teeth of the crescent-taper-ground crosscut are all the same thickness, whereas the teeth of the straight-taper-ground saw are thicker toward the center of the blade.
The uniform tooth thickness of the crescent-taper-ground saw is an obvious advantage over the varying tooth thickness of the straight-taper-ground type. Therefore, the best saws are crescent taper ground. These are indicated by the trademarks "Crescent Ground", "Precision Ground", "Segment Ground", and "Arc Ground."
Choosing and Using a Saw
Felling saws have been used by trail crews instead of bucking saws for several reasons. They are light and flex easily to conform to a backpack or horse pack. Although they are generally used by two persons, a felling saw—if it is filed properly and the cut is close to vertical—can be run easily by one person. However, with cuts much off the vertical, the free end will droop on the push stroke and oscillate violently on the return stroke.
Saws made today have solid ends (the teeth don't run to the ends of the blade). These saws are adequate for bucking and felling where it is not necessary to use the ends. But for finishing some cuts —for example, when a log is lying in the dirt—you need a saw with teeth right to the ends. If you have a choice, choose the toothed-ended saw.
An effective saw guard can be made of a section of old firehose, preferably rubber-lined, that has been slit along its length. A guard often removed can be made to fasten with Velcro to speed removal and replacement.
To carry a saw, lay it flat across your shoulder with the teeth guarded and facing away from your neck. Remove the rear handle so it won't catch on brush or limbs. In a group, you should make sure to walk last in line.
When transported, saws should have better protection than a firehose. An accidental blow with a tool or against the side of a vehicle will cause the teeth to cut through the hose and be dulled. One effective way to transport saws is between two pieces of plywood that are firmly bolted together.
The first step in cutting a log is swamping. Remove any brush, plants, etc. that may interfere with the work. Something as seemingly insignificant as a blade of grass between the teeth and kerf can jam a saw.
Check the lay of the log and decide what will happen when the log is cut. Will it roll? Will it jump? Will it drop? Plan your cuts accordingly. Sometimes it will only be safe to have one person sawing. This is often the case if the log is on a slope. Saw from the uphill side.
Before making the cut, remove the bark where the saw will pass. Bark often has dirt in it and some say bark itself dulls a saw rapidly.
When cutting green wood, sap may stick to the blade and gradually build up in thickness until the saw will bind in the kerf. To prevent this, the saw blade should be lubricated with kerosene occasionally or when the blade begins to get sticky. Kerosene for this purpose can be kept in a small flat hip flask that can be carried comfortably in the back pocket. If the cork in the neck of the flask has two to three small grooves cut down its length, the blade can be covered evenly with a thin film of kerosene by whisking the corked bottle along the saw.
Make sure the saw doesn't get into dirt or rocks at the end of a cut. Make the last few strokes with the end of the blade; if it does then drag in the dirt, only the end teeth are dulled. Put a piece of bark under the log if possible when there's a chance of running the saw into the dirt. If necessary, dig the log free where the blade will pass. The object is to keep the teeth sharp as long as possible.
A leaning tree will have grown so the fibers are quite compressed on one side. In this case it may be possible to sink the teeth in only a couple of inches before they bind. If this happens, grab an ax and start chopping. Saw a few inches and chop out the severed wood.
Often a log will be lying in such a way that the kerf begins to close on the saw before a cut is completed. This occurs when the wood is under compression, as when a log is supported at the ends and the cut is in the middle. In some cases, the cut can be continued by driving a wedge into the kerf behind the saw. Where this won't work (if there is not room to drive a wedge or the wedge won't open the kerf), the log must be cut from the bottom, or "underbucked".
Generally, underbucking should be done by one man with one handle removed from the saw. This reduces the chance of a saw's being kinked or broken if the log carries it to the ground. To underbuck, plant an ax in the log so you can use the handle as a support for the back of the saw. Cut a small notch in the handle for a guide. Some oil in the notch will let the saw run easily and reduce ax handle wear. The spring of the handle will hold the saw in the cut with uniform pressure. A log or rock can be placed under one side of the cut to hold the log up so it will be less likely to carry the saw to the ground as the cut is completed.
How a saw cuts is determined to some extent by how the handle is attached to the blade and held. Assume the saw is making a vertical cut with the teeth pointing down. With the handle pointing up, a pull stroke will be easier the farther toward the end of the handle the hands are held. The push stroke will be harder. On the other hand, with the handle pointing down, the opposite occurs. In saws that have two holes on each end (generally bucking saws), changing the handle position from the lower to the upper hole will have exactly the same effect as moving the hands several inches up the saw handle.
The difference in force necessary to make a saw stroke under different handle positions is due to the different downward forces applied to the saw. For example, with the handle up, a push stroke increases the downward force on the saw, causing the teeth to sink deeper into the wood. (This results in a deeper cut that requires more energy.) On the pull stroke a slight upward force is applied to the saw.
A saw should be stored straight. Leaving it bent (around a firepack) will bow the blade. A stored saw should be well oiled with a heavy oil. Grease dissolved in gasoline to a consistency that can be painted on also works well.
Finding Saws and Tools
Until the advent of the chain saw, crosscut saws were a common item and manufactured by several large companies. Now, I know of only one company manufacturing crosscut saws in the United States: Jemco Tool Corp. The company distributes a catalog of its saws to dealers and will direct individual buyers to the nearest supplier.
Other sources of saws and tools are secondhand stores, the odd hardware store that still has some in stock, and surplus disposed of by different government agencies.
A tool kit for crosscut saw reconditioning is available from the Century Tool Co., Inc.. The kit contains a jointer/raker tool gage, a spider (set gage) 3 1/2 inches by 2 inches, a setting stake (block), and a steel carrying case.
How a Saw Cuts
The cutting teeth of a crosscut saw sever the fibers an each side of the kerf. The raker teeth, cutting like a plane bit, peel the cut fi bers and collect them in the sawdust gullets between the cutting teeth and the raker teeth and carry them out of the cut. A properly sharpened crosscut saw cuts deep and makes thick shavings. For large timber, where the amount of shavings accumulated per stroke is considerable, a large gullet is necessary to carry out the shavings and prevent the saw from binding.