Auger Basics – information about augers and drives for digging

Auger Basics – Here’s information about using powered equipment for digging holes for foundations is a popular method that can offer economy, simplicity and effectiveness. This document will explain the differing types of equipment from one man units to very heavy-duty hydraulic attachments. Augers and Drives for large excavators, their comparative qualities and relative costs.


All units discussed comprise of a power head appropriate to the size of the stabilizing equipment, from one man to the size of the machine the power head is connected to (“carrier”). The power head will have an output shaft coupler of a particular configuration such as round, square or hex shaft capability. Augers and extensions used will have to match the coupler configuration. Augers usually consist of a pilot bit and cutting blades or teeth capable of various materials from loose soil to solid rock. “Flighting” is the helical metal welded to the shaft that transports the loosened material up the shaft to be dispersed at the top of the hole using centrifigal force of the spinning shaft. In some cases extensions can be added for deeper hole drilling (more about this later).

For the very smallest holes such as post holes for fences, small 2 hp gasoline units can provide digging capability in soft soils with diameters 2.25″ to 8 inches and depths of three feet or a little more with a 15″ extension with no flighting. Repetitive hole digging is limited. One-man hole diggers cost approximately five to six hundred dollars.

For slightly larger and deeper holes, slightly larger two-man, 5 hp gasoline units can provide digging capability in soft soils with diameters 2.25″ to 18 inches and slightly deeper depths. Extensions are offered with flighting for 3′ additional depth or 15″ without flighting. Repetitive hole digging is still somewhat limited but two-man units are much more capable than one-man units. Two man units require two operators. Cost approximately $1500.

Diggers are available in gasoline-engine, self-powered hydraulic units that tow. The motor end of the unit is a counterbalance to the auger end, which also is the end where the operator guides the augers into the ground. These models use the same augers and extensions as the two-man models. The axle width is adjustable to allow the units to fit through gates. Often used by landscapers and deck builders. Tow behind units usually cost approximately up to five thousand dollars.

A wide variety of light to medium-light pto and hydraulic power heads are available for three-point attachments for tractors. These units are somewhat limited in ability but are commonly found and used for digging fence posts in soil without many rocks. Cost about $800 plus augers.

Substantial units are available for farm tractors with category two type hitches. These are heavier units consisting of large vertical rails with pto-driven drivers. Hydraulic features allow leveling in slightly uneven terrain so vertical hole drilling can be accomplished. Adequate down pressure from the rear mount of the tractor allows drilling through rock, colleci, shale etc. in many cases. These units are capable of drilling holes to 36″ diameter in depths to four feet. Price approximately five thousand dollars.

The most popular and effective hydraulic drilling units available for “carriers”- skid steers, backhoes and excavators. These units dangle from an adapter made to each type of carrier and are used for drilling vertical holes. The power head consist of a hydraulic motor usually coupled to a planetary gear transmission, a coupler and an auger and extensions.  Digging into rock is accomplished by backhoes and excavators as they offer down pressure that is not offered from skid steers. Hydraulic digger models are assigned to match the hydraulic flow rate and operating pressures of the main bucket curl hydraulic circuit for the carrier, with consideration to the type of material to be dug. 

Drilling depths mostly depend on the height capability of the carrier and the combination of auger and extensions. Augers come standard in four foot lengths and fixed or variable-length extensions. Custom augers may incorporate extensions with flighting. Augers are available in standard sizes to 36″ diameter by four foot lengths, in three models for dirt, dirt and fractured rock, and “bullet tooth” model which digs all. Digging holes to 10 feet is commonly done. Kelly Bars – telescoping square shafts and custom extensions extend digging depths to approximately 20′.


There is a myriad of equipment for augering. Equipmentland is well versed in all the popular types of auger equipment. Contact us today for more information about your specific need. See more here.

Jeff Dayne,