Earth Auger

The most common design of earth auger has a helical screw blade (the flighting) winding around lower part of the shaft. The lower edge of the screw blade scrapes dirt at the bottom of the hole, and the rest of the blade acts like a screw conveyor to lift the loose soil out of the way. When the hole reaches the desired depth and the tool is pulled out, the screw blade scoops out the remaining loose dirt.^{[citation needed]}

The rod may end in a sharp point protruding below the screw blade. Its purpose is to push the dirt that lies just below the rod to the sides, where the blade can pick it up. It also helps keep the hole straight by prevent the auger from wandering off to the side. The lower edge of the screw blade may have teeth.

Another type of earth auger has two vertical blades instead of a helical screw. Rather than scraping the soil at the bottom of the hole, this type of auger cuts a cylindrical plug out of it, that is held by friction between the two blades. The auger must then be pulled out and emptied every foot or so. This type may require less force to operate, but may be adequate only for certain types of soil.

Hand-powered earth augers are typically used to plant saplings and trees or to set up posts for fences or other ends.^[7]

Large mechanized earth augers, called drilling rigs, are used to make holes for piles destined to be deep foundations or retaining wall.^{[citation needed]}

Gas- or hand-powered augers are used by ice fishermen to drill through the ice layer over lakes or rivers.