The machine
A stump grinder is essentially a heavy steel disc studded with carbide-tipped teeth, driven by a petrol or diesel engine and mounted on a frame. The wheel spins fast; the teeth do the cutting.
They come in three broad sizes. Walk-behind machines that fit through a standard 750mm gate. Self-propelled tracked machines, which are faster and need about a metre of clearance. And tractor or excavator-mounted attachments for large stumps with open access.
The size that fits your access is the single biggest factor in how long the job takes, which is why a narrow side gate can double the price of an otherwise simple stump.
The process, step by step
Locate services. Irrigation, electrical, dog fence wire, stormwater. This is not optional - a grinder wheel that hits a service does expensive damage in a fraction of a second.
Clear the area. Rocks, pavers, star pickets, old fencing wire and general debris are removed. Anything metallic near the stump will destroy teeth and become a projectile.
Set up protection. Boards, mats or plywood are placed to catch thrown chip and protect windows, cars and neighbouring surfaces.
Cut the stump low. If the stump is standing proud, a chainsaw takes it down close to ground level first so the grinder is not wasting time on material a saw could remove faster.
Grind in layers. The operator positions the wheel over the edge of the stump, swings it laterally across the face, then lowers it a few centimetres and repeats. The stump is removed in horizontal layers rather than being attacked from one side.
Follow the flare. The visible trunk is narrower than the root flare beneath it. The operator works outward to take the buttress roots down as well, which is why the finished hole is wider than the stump looked.
Finish at depth. Typically 200 to 300mm below the surrounding grade, deeper if turf or replanting demands it.
Clean up. Chip is raked back into the void or removed, and the surrounding area is tidied.
What is left behind
A void filled with a mixture of woodchip and soil, slightly proud at first because chip occupies more volume than solid timber did.
Over about a year the chip decomposes and the ground settles, so expect to top it up once. If you are laying turf straight away, take the chip out and backfill with soil instead.
Deeper roots stay in the ground. They cannot produce leaves without the stump, so they die and break down over several years without causing problems.
Safety
Grinders throw material hard and unpredictably. Exclusion zones apply, and bystanders - particularly children and pets - need to be genuinely inside, not just nearby.
The operator wears eye and face protection, hearing protection, gloves and boots. Anything metallic hidden in the stump is the main hazard, which is why the preparation step matters.
Where grinding is not enough
If a slab, pool, driveway or footing is going over the stump, grinding leaves timber under the load and the ground will settle unevenly. That is a job for full excavation, and the comparison is here.
For a quote, ring (07) 5408 6029 with the species, the width at the base and the access width. What it costs is covered separately.
Frequently asked questions
How does a stump grinder actually work?
A heavy steel wheel studded with carbide-tipped teeth spins at high speed. The operator swings it side to side across the face of the stump, taking off a layer a few centimetres deep with each pass, then lowers it and repeats. The stump is reduced to chip in place rather than being pulled out.
How long does grinding a stump take?
A small softwood stump on open lawn can be done in twenty minutes. A wide hardwood flare with restricted access can take two hours or more. Diameter across the root flare, timber hardness and the size of machine that fits through the gate are the three variables.
Does it damage the surrounding lawn?
Minimally. The machine tracks across the grass to reach the stump, which marks it temporarily, and chip is thrown around the work area. A crew will normally place boards or a mat to catch the chip and rake the area down afterwards. Compared with excavation, the disruption is small.
What needs to be done before the machine arrives?
Locate and mark services - irrigation lines, dog fence wire, electrical, and anything else under the surface. Clear away rocks, pavers, star pickets and any old fencing wire near the stump. A grinder wheel that finds a steel picket destroys a set of teeth and throws debris hard.