Lee Valley Tools Woodworking Newsletter
Vol. 1, Issue 5
July 2007
What Is It?

J. Boggs Patent Saw Set

Almost all wood cutting saws require the teeth to be wider than the body of the blade. This is referred to as set. Without it, the blade will eventually bind, as the wood fibers recompress against it. One method of creating set is by bending all the saw's teeth slightly in an even, controlled manner, with alternate teeth being bent in opposite directions. This allows the saw blade to cut without wandering, enabling the sawyer to maintain line and cadence. Some manufacturers taper grind their blades to further facilitate that clearance. However, set does not guarantee that a saw will cut cleanly or with any speed; the sharpness of the tooth and the particular rake angle determine movement of a saw blade through material.

The early saw set shown here is the hammer type. To use it, a saw blade is inserted between a shaped punch and a fixed-angle anvil. The punch is struck, and the tooth is offset. Clearance is maintained by the spring, which moves the striker up and away after each hammer blow. The saw blade is held in position with the moveable rest, which allows for parallelism as the blade is moved across the anvil.

  In use.

This saw set is conspicuously marked with, "J. Boggs", "Patent", and the owner's initials "MT" in a cartouche. A patent search indicates that John Boggs of Philadelphia, Pennsylvania was issued a patent for a saw set on October 4, 1827. On December 15, 1836, a fire destroyed the United States Patent and Trademark Office (U.S.P.T.O.). The first 10,000 (approximately) American patents and models were lost in the fire. (Diligent members of the office staff were able to save some.) The search further shows that this patent was reissued under the X-patents (refers to U.S. patents issued between 1790 and 1836, before the U.S.P.T.O. began numbering patents) and given the number 4888x. No abstract or claims paper is available for examination. Although this saw set is clearly marked and closely resembles the patent drawing, it is not an exact copy. This is a common practice in the transition from invention to commercial manufacture.



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