how-are-auger-bits-manufactured

How are auger bits manufactured?

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An example of a Russell Jennings pattern auger bit Auger bits are partly machine produced, and partly forged and ground by hand. As they are produced in a number of different patterns, this guide covers the basic manufacturing process for a standard Russell Jennings pattern auger bit.

For more information on patterns, see: What are the different auger bit patterns?

Auger bit blank during the forging process

Step 1 – Forging the blank

Steel bars are heated to a temperature of 900 degrees centigrade.

Image showing the drop forging process by which spade bits are manufactured One end of each bar is flattened with a pulsating power hammer to produce a long, thin strip of metal on the end of a cylindrical shank.

For more information on the type of metal used, see: What are auger bits made of?

An auger bit blank that has been clamped in a twisting machine and given its characteristic spiral shape.

Step 2 – Creating the flighting

The blank is reheated, and clamped into a twisting machine, which creates the characteristic spiral shape of the auger.

A heated auger being clamped repeatedly in a toothed vice to make sure its diameter is uniform across its entire length For the bit to work properly when complete, all of the twists in the spiral flighting must be uniform. To make sure this is the case, the bit is reheated and repeatedly crimped in a toothed vice. This keeps the diameter of the tool consistent.
Blacksmith shaping the tip of a wood boring auger with a power hammer

Step 3 – Shaping the guide screw

Once the flighting is complete, the tip of the bit is reheated, then slammed under a drop hammer that forces the end point into a die.

Newly forged auger bit having the excess material from having its tip created removed Waste material created by this process is clipped away from the end of the bit with a clip press, leaving behind the basic shape of the guide screw.
Grinding thread into the tip of an auger bit on a ridged grinding wheel Thread is ground into the guide screw on a ridged grinding wheel.
Trimming the shank of an auger bit on a machine-controlled lathe

Step 4 – Preparing the shank

The shank of the drill is then cut down to the right size on a lathe.

A red hot bit being quenched in a bath of water

Step 5 – Heat treating

Now that it is the right basic shape, the auger bit is reheated in a forge before being plunged into cold oil. The rapid cooling alters its molecular structure and causes it to harden.

Machine grinding an auger bit to ensure uniformity of diameter after heat treating

Step 6 – Grinding and sharpening

In its hardened state, the auger is ground to a precise diameter to remove any deformities that may have occurred during the heat treating process.

Grinding the inside of auger bit flighting to reduce internal friction The inside of the flighting is then ground by hand to a smooth finish. This helps to make sure that wood shavings can travel along the spiral without getting stuck on a rough surface.
Grinding the spurs and lips sharp on an auger bit Finally, the lips and spurs of the bit are sharpened on a grinding wheel.
An auger bit clearing waste wood from a bore hole as it drills The auger is now ready to start boring.
Wonkee Donkee insists that there is nothing boring about wood boring augers