The cutting principles of the wood auger drill bit, once explained, are quite simple. The auger adds a long deep spiral flute for effective chip removal. The most popular wood auger drill bits are used in hand braces.
The first wood auger drill bit used is the Jennings or Jennings patterned bit, which was developed by Russell Jennings in the mid-19th century. The Jennings wood auger drill bit has a self-feeding screw tip, two radial cutting edges and two spurs, as well as a double flute starting from the cutting edges, and extending several inches up the shank of the bit, for waste removal.
The second pattern that is popular with wood auger drill bits is the Irwin auger bit, commonly called the solid-center auger bit. This style of bit was invented in 1884, and the rights sold to Charles Irwin who patented and marketed the wood auger drill bit in 1885.
The only difference between the Irwin and the Jennings bit is that one of the cutting edges on the Irwin has only a vestigial flute supporting it, which extends only about half an inch up the shank before ending, while the Jennings bit continues full-length up the shank for waste removal. Because of this, the Irwin bit may afford greater space for waste removal and greater strength because the design allows for a center shank of increased size within the flutes, as compared to the Jennings bits, as well as smaller manufacturing costs.
Both styles of wood auger drill bits were manufactured by several companies throughout the early- and mid-20th century, and are still available new from select sources today, such as from the Onsrud Cutter company.
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