Short answer
Everything about drilling with an auger comes down to two things: ENTERING SQUARE and letting the flight carry material out rather than forcing progress. Enter at an angle and the hole goes oval, the flight rubs the side wall and jamming begins; push too hard and the material cannot be carried out, the flight packs and the auger turns without advancing. The correct method is to work with steady, moderate down pressure and lift the auger out to clear it once the flight fills.
Before you start
- A buried services check: post and fence holes are shallow, but so are irrigation, power and telecoms lines.
- Flight diameter and type: what the hole is for sets the diameter; the ground type sets the type of point.
- Ground type: loose soil, clay, stony ground and rock all behave differently and want different methods.
- Carrier stability: an auger generates turning torque; the tracks or outriggers need firm, level ground.
- Where the spoil goes: soil piled at the mouth of one hole is underfoot while drilling the next.
Step by step
- 1
Mark the point and position the machine
Mark the centre of the hole and place the machine so the auger comes down square on it. Positioning the machine correctly is faster than trying to correct the angle by extending the boom.
- 2
Bring the auger square
The axis of the flight has to be perpendicular to the ground. An entry that is not square makes the hole oval and causes the flight to rub the side wall; most jams start here.
- 3
Start slowly and let it centre
Over the first few centimetres the aim is not progress but letting the flight find its centre. Once the point has bedded and is turning, down pressure is increased gradually.
- 4
Advance with steady pressure
The auger draws itself in; your job is to keep it balanced, not to force it. Excess pressure does not increase progress, it packs the flight and raises the risk of jamming.
- 5
Lift and clear once the flight fills
When material builds up on the flight and can no longer be carried out, the auger is lifted from the hole and spun clear. Done regularly, this keeps the work continuous.
- 6
Stop if stone or rock appears
Where the auger suddenly loads up, the sound changes or the machine is pushed against the auger rotation, there is stone or rock. Do not force it; back the auger out and assess the obstruction.
- 7
Clean and measure the hole
Loose material left at the bottom is removed and the depth checked. Doing that before the post or the plant goes in is faster than reopening the hole afterwards.
Do and don’t
Do
- Bring the auger down square and keep it square throughout.
- Lift and clear the flight once it fills; do not let material build up in the hole.
- Lift and clear more often in sticky clay.
- Stop and assess on the sound of stone or a sudden load.
- Position the machine on firm, level ground; the auger generates torque.
Don't
- Do not enter at an angle; the hole goes oval and the flight jams.
- Do not try to force a jammed auger forward; use the reverse rotation recovery instead.
- Do not try to go faster with excess down pressure; the result is the opposite.
- Do not widen the hole by using the auger as a lever; the shaft and gearbox are not made for it.
- Do not let anyone near a turning flight; the working area stays closed.
If the auger jams
Forcing a jammed auger further in deepens the jam. The right move is to reverse the rotation and recover the auger upwards. During recovery, use the auger's own rotation rather than pulling with the machine's lift force; otherwise the load goes into the shaft and its mountings.
What changes with the ground
- Loose, sandy ground: fast progress but the hole wall can collapse. The hole is used immediately after drilling.
- Clay and damp ground: material sticks to the flight. It has to be lifted and cleared more often.
- Stony ground: the auger can wander when the flight catches a stone. Staying square gets harder and progress slows.
- Rock: a standard flight will not progress. Either an arrangement with a point suited to rock is needed, or the method changes.
- Frozen ground: the top layer is hard and the layer beneath is soft; entry is difficult, the rest is normal.