If you’re asking “can a mini excavator dig post holes?”, the answer is yes when the machine is fitted with a suitable hydraulic auger. A mini excavator with an auger can make post-hole work much faster for fencing, retaining walls and landscaping, but the right auger diameter, required hole depth and ground conditions all matter.
Quick answer
A mini excavator can dig post holes using a hydraulic auger drive fitted to the machine. Digger2Hire’s Kubota U17-3 1.7T mini excavator includes an Auger Torque X2000 drive with 300 mm and 450 mm augers.
The 300 mm auger suits jobs that call for a narrower hole, while the 450 mm auger removes substantially more material and suits jobs that require a wider diameter. The correct hole size should come from the requirements of the job rather than simply choosing whichever auger is available.
Ground conditions can change the job considerably. Workable soil may drill cleanly, while compacted clay, roots, buried material or rocky ground can slow progress or prevent an auger from completing the hole as planned.
How does a mini excavator auger work?
An excavator auger uses the machine’s auxiliary hydraulics to rotate a helical auger into the ground. As it turns, the cutting end breaks into the soil and the flights carry loosened material upward.
The operator periodically lifts the auger from the hole so material can clear from the flights. The process continues until the required depth is reached or ground conditions prevent further drilling.
The excavator’s boom and arm make it possible to position the auger over the marked hole. Keeping the auger reasonably vertical as drilling begins is important if you want the post hole to follow the intended line.
Digger2Hire’s Kubota U17-3 using an excavator auger to drill a post hole.
What post-hole jobs can an excavator auger suit?
Post-hole work comes up in plenty of residential and landscaping projects. Depending on the design, engineering requirements and ground conditions, an excavator auger can be useful for:
- fence posts
- retaining-wall posts
- landscaping posts
- pergola and similar structural posts where the specified hole suits the equipment
- planting holes where an auger is appropriate
- other repeated holes that suit the available auger diameter
The excavator and auger only create the hole. They do not determine the required diameter, depth, post size, footing design or engineering requirements for the structure you’re building.
Should I use a 300 mm or 450 mm auger?
Choose the auger diameter to suit the hole the job actually requires.
A 300 mm auger removes less material and may suit narrower post holes. A 450 mm auger creates a substantially wider hole and may be required where the post, footing or project specification calls for the extra diameter.
The difference is larger than it can appear just by looking at the numbers. At the same depth, a 450 mm-diameter hole has about 2.25 times the cross-sectional area of a 300 mm-diameter hole. That means considerably more material needs to be cut and removed.
Don’t use the 450 mm auger simply because bigger sounds better. If the job only calls for a 300 mm hole, the larger auger means disturbing and removing more ground than necessary.
How deep can you drill a post hole?
There is no useful universal answer based only on the excavator’s size. Post-hole depth depends on the auger setup, ground conditions, machine position and the requirements of the job.
Don’t confuse the excavator’s maximum bucket digging depth with auger drilling depth. The Kubota U17-3 has a manufacturer-rated maximum digging depth of 2,310 mm with a bucket, but that specification does not tell you how deep a particular auger setup should drill.
Work out the required post-hole depth first, then confirm that the available auger setup is suitable before arranging the hire.
What happens when the auger hits clay?
Clay can make augering slower, particularly when it is heavily compacted or sticky enough to build up on the flights. The exact behaviour depends on the clay and its moisture content.
If the auger stops making sensible progress, forcing it harder is not automatically the answer. Stop and work out what the ground is doing before continuing.
What happens if the auger hits roots or rock?
Roots, rock and buried material can change a straightforward post hole very quickly. Small roots or minor obstructions may be manageable depending on the auger and conditions. Larger roots, substantial rock or buried construction material may stop the auger or require a different approach.
An auger is not a universal rock-drilling tool. If you encounter material the auger is not suited to, continuing to force the equipment can waste time and risk damage.
Mark the post-hole positions before you start
Repeated post holes are much easier to approach when the locations are already measured and clearly marked before the excavator starts drilling.
For a fence or retaining wall, work from the relevant plan or layout rather than deciding the spacing from the excavator seat. Check measurements before drilling because moving a hole after it has been augered is not as simple as moving a paint mark.
Check underground services before using an auger
This matters for any excavation, and an auger is no exception. You need to consider what may be underground before drilling starts.
Before You Dig Australia provides information from participating asset owners about underground infrastructure around proposed work areas.
Don’t assume your own property is clear simply because you’re working in a backyard. Private electrical, water, irrigation, drainage and other services may not appear on supplied plans, and recorded asset positions or depths should not be treated as exact.
If you’re not confident about what is below a proposed post hole, sort that out before putting the auger into the ground.
Is a 1.7T mini excavator good for post holes?
A 1.7T mini excavator can be a practical post-hole machine for residential work because it combines compact access with useful hydraulic capability.
The U17-3 can retract to 990 mm wide, which helps it reach many residential work areas. Once on site, the Auger Torque X2000 and included 300 mm or 450 mm auger can be fitted for suitable post-hole work.
The U17-3 package also includes three buckets, a ripper and hydraulic rock grabber, so the same machine can handle other excavation and material-handling tasks around a project. See the full package on our equipment and attachments page.
For a broader look at the jobs this machine can handle, read What Can a 1.7T Mini Excavator Do?
Can a first-time operator use an excavator auger?
Being new to mini excavators does not automatically rule out dry hire, but take time to become familiar with the machine before starting post-hole work.
At handover, Digger2Hire can give you a rundown of the U17-3 and its basic controls. Start with deliberate movements and make sure you understand how the boom, arm and auxiliary hydraulic control respond.
If this is your first time hiring a machine, our guide Do You Need a Licence to Operate a Mini Excavator? covers first-time operators and private dry hire.
When might an auger not be the right approach?
An excavator auger is useful, but it is not the answer to every hole. You may need another approach where the ground contains substantial rock, large roots, buried concrete or other material the auger cannot sensibly cut.
The job may also have specific engineering, structural or site requirements that determine how the holes need to be excavated. The equipment should suit those requirements, not the other way around.
Can a mini excavator dig post holes?
If you’re asking can a mini excavator dig post holes, yes: a suitable mini excavator fitted with a hydraulic auger can efficiently drill post holes for many fencing, retaining-wall and landscaping jobs.
Choose the auger diameter to suit the required hole. Digger2Hire’s U17-3 includes 300 mm and 450 mm augers with an Auger Torque X2000 drive, giving you two useful post-hole sizes as part of the hire package.
The biggest variables are the required diameter, hole depth, ground conditions, underground services and site access. Work those out before assuming the auger will suit the job.
About this guide
This guide explains the practical use of a hydraulic auger on a compact excavator, using Digger2Hire’s Kubota U17-3 and Auger Torque X2000 setup as a real hire example. Machine and auger suitability still depends on the required hole dimensions, ground conditions, access and the requirements of the project.
Sources and equipment information
- Kubota Australia: U17-3 mini excavator specifications
- Auger Torque: X2000 auger drive
- Before You Dig Australia
Planning a post-hole job?
Have your job location, required hole diameter and depth, number of holes, access width and a few photos if useful ready. Your local Digger2Hire operator can help you work out whether the U17-3 and included auger setup are a sensible fit before the hire is arranged.
Need help choosing?
Choose your hire location
Select your location to speak directly with your local Digger2Hire operator about the job, access, machine and attachments.
Hire availability and next steps
Compare the included excavator attachments and Kubota U17-3. For local availability, see Brisbane dry hire or Northern Rivers dry hire. Tweed Heads customers can also see Tweed Heads hire and collection.