Good filers are few and far between. The filer's work is exacting and requires a lot of stamina and patience. Back in 1939, George C. Parker wrote in the West Coast Lumberman: "There is today a scarcity of crosscut saw filers. This dearth of filers has gradually made itself manifest during the past 10 years. Filers are not made overnight. Years of practical experience are necessary before they become skilled and efficient."
Today crosscut saw filers are much scarcer than they were in 1939. Treat any you know with respect, but insist on excellence in the work they perform. Ask them the number of saws they sharpen each year--more is better. Avoid filers who recommend only one setting for all types of cutting conditions. Our traditional crosscut saws cut well only when they are sharpened properly. The sawyer needs to tell the filer the expected cutting conditions. For example, cutting green blowdown in winter requires different raker and teeth set than cutting dry, beetle-killed snags. It is important to communicate this information to the filer.
A few others and I are working with saw designers to create a saw that not only meets our trail clearing needs, but also can be sharpened by using a simple jig. Such a design is technically possible. But is unlikely that such a design would cut as well as a well-tuned vintage crosscut saw.
The Crosscut Saw Manual by Warren Miller (1977, rev. 2003) is an excellent source of information on filing. Another good publication is Saws and Sawmills for Planters and Growers by John Morris (1991).
A filer needs to work in a well-lit location with a wooden vise that sandwiches the saw to hold it firm. I prefer vises that are heavy and massive rather than those that are lightweight and flimsy.
Specialized saw tools that every filer used to have are no longer being manufactured. Some replicas are being made, but vintage saw tools are superior. I am particularly fond of Anderson Tools. These tools are truly antiques and would be difficult to replace if lost or damaged. Files and sharpening stones are readily available, but tools like jointers, raker and pin gauges, anvils, and swaging hammers are scarce.
Straightening is an art in itself. The filer must move the metal carefully by hammering the blade on an anvil. A special saw filer's hammer has slightly curved surfaces to work the metal back into place. I have sometimes spent more time trying to get a saw straight than I have spent sharpening it (figure 20).
After the saw has been cleaned and straightened, jointing is the first step in sharpening. A tool called a jointer holds the file. The points are filed off the cutter tips so that each of them lies on the circle of the saw (figure 21). With each of the teeth lightly touched, this arc will become the reference plane for fitting rakers and sharpening teeth.
I use a triangular file to shape the raker gullet. A raker gauge is placed on top of the cutters that have already been jointed to form the reference plane. With the rakers sticking up through the gauge, the rakers are filed down to a predetermined stop. Swedged rakers are fitted differently. They are hammered to a pin gauge (figures 22 and 23).
Each tooth is sharpened to a point (figure 24). The filer has the option to make the bevel suit the wood that is being cut. It is very important that all the teeth are the same height in relationship to the rakers (figure 25).
The teeth need to be set so they track directly behind one another in a measured angle offset from vertical. The filer puts equal set in all the teeth by hammering the point over a beveled hand anvil (figure 26). The set is checked using a tool called a spider to tolerances of 5/1,000 of an inch.
After setting the teeth, I side-hone them to further ensure they all have the same set. I recommend this procedure even though it is not commonly mentioned in saw sharpening literature.
A final word about filing--If saws consistently come back from the filer but do not run smoothly and sing...find another filer.