Augers and Drilling Tools

Get expert advice on choosing augers and other drilling tools for projects around your farm that require drilling into the earth down to the frost line.

Bobcat

A full day's work can be reduced to merely a couple of hours if you have access to more dedicated equipment.

Photo courtesy Bobcat

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I remember the day my wife and I came home after signing the papers to purchase 80 acres of very rough land. It was something we had wanted to do for a long time, but the reality of knowing that we actually owned the land made me determined to be productive with our purchase.

We sat at the kitchen table and discussed plans that night. I wanted to create an area that would attract wildlife and provide hunting opportunities for our family. I also thought about ways to use the land’s resources to help us make the payments that would be arriving every month. I had read about a growing market for locally produced table and wine grapes in our area, and over a celebratory glass of wine that night, we decided to plant grapevines.

After a lot of research that winter, we settled on varieties of grapes that could withstand our cold winters and short growing seasons in northern Minnesota. I attended several seminars on the basics of planting and growing grapes, which suggested that I would need to fence my vines to protect them from the wildlife I was encouraging to expand on our property. I would also have to build trellises to support the grapevines. What I wasn’t aware of at the time was that to accomplish my trellising and fencing, I would have to dig a lot of postholes – almost 60 of them – for a relatively small 5-acre vineyard.

I’d dug postholes by hand over the years for things like gates, decks and small fences around the house, and I’d driven my share of metal fence posts for wire fences, but the thought of digging all those 6- and 8-inch posts by hand had me a little apprehensive. Our soil was a mix of sandy loam with some clay and rock mixed in.

Where I live in Minnesota, wintertime brings frozen lakes and ice fishing. I own a powered ice auger, and with a little research, I found that I could purchase an Earthworks auger that would fit my Jiffy ice auger power head. With my newly equipped auger attachment and a cover on the power head to protect the carburetor from dust and dirt, I tackled the posthole digging with renewed confidence and was able to get the holes drilled and posts set in time for spring vine planting. I won’t say it was easy work. In fact, at the end of each day, I felt like the auger had won the fight, and most parts of my body ached from the constant vibration and the unexpected jolting when I hit roots or the occasional rock.

Although I complained about the physical abuse I received from the auger, I might have been digging holes for weeks if I would’ve had to dig them by hand with a clam shell or manual posthole auger.

It’s been several years since my initial experience with digging multiple postholes, and I have learned a few things that would have been helpful to me at the time. If you are going to be undertaking a project that requires digging postholes, and you are new to the process, here are some of the basics to keep in mind.

Clamshell digger

I would venture a guess that most people who live on a farm or ranch, no matter the size, probably have at least one type of hand posthole digger tucked away in a shed or garage. From digging holes for footings when building decks or sheds, to setting fence corner braces and gates, rural people are not strangers to digging postholes by hand and setting posts below the frost line. If you have just a few holes to dig, and your soil is not too thick and heavy, the clamshell style digger is probably the most popular type used.

As its name implies, the clamshell has two cupped and pointed shovels mounted to wood handles. Holes are dug by spreading the jaws of the shovels and dropping them down on the predefined posthole area. The handles are then pinched together, lifting out the soil which is dropped outside the hole, and the process continues until you reach your desired depth.

 It helps to dig your holes in soil that is not too dry. After a rain is the ideal time to dig if you are in light soil. Heavy, clay-based soil can be a real chore with a clamshell digger. If you do have clay soil, wetting the shovels of the clamshell in a bucket of water after each “pinch” will help to loosen the clay, which still may need to be knocked off the shovels by striking them against the ground.

Clamshell diggers range from $17 up to $70. A good-quality clamshell can be purchased for around $30. The more expensive diggers usually come with fiberglass handles and heavy gauge shovels. Keep in mind that the weight of the clamshell increases with the fiberglass handles, which can be more tiring to use.

Posthole auger

The posthole auger – a one-piece metal bar with a pointed auger head that’s open in the middle – is another popular hand digger. The metal shaft of the auger is topped by a  cross handle. Hand augers are usually designed to dig 6-inch-diameter holes. Unlike a clamshell digger, hand augers are twisted using torque on the T-handle until the auger fills with soil. It is then lifted out of the hole, and the soil is dumped, continuing the process until you reach the desired depth.

I personally prefer the hand auger for smaller jobs, because the auguring action can cut through some smaller roots as opposed to the clamshell. Hand augers are a little more expensive than clamshells, from around $50 to $70 – and again, price difference is driven by the style and quality of the auger head.

Powered augers

If you have more than just a couple of holes to dig, you may want to consider buying or renting a powered auger. Power augers come in one- and two-man configurations and are very powerful machines that produce a lot of torque. A powered auger will allow you to drill up to 30 holes a day if you have loamy or sandy soil, but rocky or heavy clay can cut the output in half.

The engine that sits on top of the auger – referred to as the power head – can be either two- or four-cycle, and the engine size varies from around 40cc to 60cc for a one-man unit up to 190cc for a two-man auger. Augers that attach to the power head are matched to the size of the desired hole diameter. Augers range in size from 4 to 12 inches. As a reference, a 4-by-4 post requires an 8-inch auger, while steel posts use a 4-inch auger. Most powered augers will dig holes up to about 3 feet deep, but if you need to go any deeper, you might purchase or rent an extension bar to attach to the power head.

As I mentioned earlier, powered augers can make digging multiple holes quite a bit faster, but just because an engine is turning the auger for you, don’t underestimate the physical requirements of using one. With the added torque produced by the engine, if you hit a big root or rock, the auger can literally throw you around if you aren’t prepared. Two-person versions require two people to operate it, and with the increased power comes extra weight. Moving any auger from hole to hole, and lifting it out as you bore deeper can be back-breaking work. Make sure you are up to the physical demands of using one all day.

Prices for the power head of the augers vary from $190 for a 43cc unit to more than $400 for a 190cc two-man unit. Augers that are purchased separately run from $119 to more than $200, depending on the diameter of the auger. If you don’t plan on using an auger for more than a few days a year, renting one from an equipment rental shop may be a good option. Rates start at around $60 a day for a good unit – and usually come with some helpful advice from the store owner on operation and use.

3-point posthole diggers

If you own a tractor and you will be digging a lot of holes, the 3-point mounted posthole digger is another option to consider. These units take advantage of the tractor’s 3-point connection and power take-off (PTO) to move the auger around and dig holes. The auger is suspended from a boom, and attached to a gear box. Lowering the tractors 3-point to the ground starts the auguring process. There are models designed to work with a variety of tractor horsepower, from 20-hp category-1 tractors up to 75-hp category-2 tractors.

Using your tractor’s 3-point hitch and PTO to dig holes eliminates a lot of the physical labor required when lifting and moving a one- or two-person powered auger, and the work can be done by one person sitting on a tractor. As with any of the augers, soil consistency and composition will determine how fast and how many holes can be completed in a day.

If you require a heavy-duty posthole digger that will see repeated use on a

daily or several-times-a-year basis, there are models available that can be mounted to the tractor’s bucket, or with a boom to the 3-point hitch, that use the tractor’s hydraulics for delivering added torque to the auguring process. Hydraulic style diggers are very popular for large agricultural, landscape and commercial applications. One of the biggest advantages of a hydraulic auger is that if the auger becomes stuck – and they will – it has the ability to reverse itself. They also offer features such as shutting themselves down if they exceed their torque limit, preventing damage to the unit.

All of the tractor-mounted augers come with a choice of diameter, from 6 inches up to 24 inches. Prices for 3-point hole diggers range anywhere from around $600 to $1,200 for 3-point units, with hydraulic-assisted models starting around $1,000 and going up to about $3,000 depending on auger size and mounting capabilities. You may want to rent a unit to find out how it works with your tractor – and also to get an idea of how easy or difficult they are to operate – before you purchase one. One-day rentals can be found for around $90 per day or about $360 per week at most equipment rental shops.

Regardless if your next project involves fencing, adding a deck or shed, or even planting some trees, take the time to research some of the options available to help you get your postholes completed as efficiently as possible – and with the least amount of time and labor.  


Tim Nephew is a freelance writer living in Minnesota, where he owns and maintains 80 acres for wildlife to enjoy.