In the solid-center auger bit one of the cutting edges has a "supportive flute”, which extends only about 1/2" (12 mm) up the shank before ending. The other flute continues full-length up the shank for waste removal. This type of Auger bit (also known as The Irwin bit or Ship Auger 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 Jenning bits). This style of bit was invented in 1884, and the rights sold to Charles Irwin who patented and marketed this pattern the following year.

Both styles of wood auger drill bits were manufactured by several companies throughout the early- and mid-20th century, and are still available from select sources today, such as from DIMAR CANADA. 

The cutting principles of the auger bit are simple yet very effective. The center of the bit is a tapered screw thread. This screws into the wood as the bit is turned, and pulls the bit into the wood. There is very little need for any force to push the bit into the work piece. This is ideal bit for a hand tool. The radial cutting edges remove a slice of wood of thickness equal to the pitch of the central screw for each rotation of the bit. To pull the bit from the hole, either the female thread in the wood work piece must be stripped, or the rotation of the bit must be reversed.

The edge of the bit has a sharpened spur to cut the fibers of the wood, as in the lip and spur drill bit. A radial cutting edge planes the wood from the base of the hole. The Auger adds a long deep spiral flute for effective chip removal.

Features & Benefits

• Self feed spur for fast and effortless material penetration
• Front dual cutting edge for maximum durability and precision
• Greater flute space  for faster chip removal during drilling
• Hardened alloy steel provides superior bit life
• DIMAR Auger bits HEX-SHANKS balled grooved (¼” and 7/16") allows for quick bit changes, and are fully compatible with all Quick-Change brands on the market, such as Milwaukee, Irwin, DeWalt, Bosch, Black & Decker and our own brand Snappy. Our HEX shanks conform to the American National Standards Institute - ANSI B107.4
• From Cutting Diameter 1/4” to 3/8” Hex is 1/4”
• From Cutting Diameter 7/16” to 1-1/2” Hex is 7/16”