Almost every forestry attachment sold in Australia was designed, rated and filmed somewhere else. Trevi Benne builds in Italy, Dipperfox in Estonia, Shearex in Canada, Powerhand in Scotland and OMEF in Italy. All of them make capable equipment, and all of them developed their published capacities in timber that behaves nothing like a mature spotted gum or a paddock ironbark. The attachment does not change when it lands in Australia. The material does, and that single difference is responsible for most of the gap between what a buyer expects and what the machine produces in its first month.
Buying rule
Treat every published diameter, cycle time, production rate and tool-life figure as a softwood or mixed-hardwood reference point, not a forecast. Confirm performance in the species, size and moisture condition you actually work in, on your own carrier, before the number enters a tender.What density and interlocked fibre actually do to an attachment
Two properties of Australian hardwood drive nearly all of the effect. The first is density. Dry eucalypt and acacia timbers sit well above the softwoods that dominate northern-hemisphere forestry, and green density is higher again because the same dense cell structure is carrying water. Density translates directly into the force required to push a blade through a section, into the energy a mulcher rotor must put into every particle it makes, and into the mass of whatever the machine is left holding after the cut.
The second property is fibre behaviour. Many eucalypts carry interlocked or spiral grain, where successive growth layers run in opposing directions. Softwood splits ahead of a blade and helps the tool do its work. Interlocked hardwood resists splitting, so the tool has to sever more of the section rather than wedging it apart. Practically, that means a shear blade meets resistance all the way through instead of falling through the last third, a mulcher produces stringy rather than clean chips, and a stump screw finds root wood that tears instead of parting. Add the silica and grit that accumulates in bark on dusty sites, and the abrasive load on every cutting edge rises as well.
Where the extra force shows up
On a tree shear the effect is visible as a longer, slower stroke and a higher share of stems needing a second bite or a chainsaw finish. A shear that closes decisively on 250 mm pine may labour on 250 mm box, and the loss is not one big failure but several seconds on every stem, multiplied by the stem count. The same pressure and flow questions covered in hydraulic matching become sharper, because the circuit is being asked to hold near its maximum pressure for longer on each cycle.
On a forestry mulcher the cost appears as rotor speed recovery. Every bite pulls rotor speed down, and the head spends the next fraction of a second getting it back. Denser fibre takes more energy per particle, so the recovery is slower, the head bogs sooner and the operator has to feed more gently. A Shearex VM-50SR with a published optimal target material diameter of 25 cm will still cut 25 cm hardwood, but the hectares per hour at that diameter can differ substantially from the same head working regrowth. That is a production question, not a capability question, and it is the reason maximum diameter is not production diameter.
On a Dipperfox stump grinder the variable is resistance through the profile. The screw passes through butt wood, then root intersections, then soil, then wood again, and dense hardwood raises the torque demand at every transition. This is why Dipperfox publishes first-gear torque figures at all, and why a carrier sitting at the bottom of the permitted flow band will feel very different in ironbark from how it felt in a demonstration video. On a grapple saw the effect is chain: cut times lengthen, chain dulls faster, and the bar and sprocket consume more of the job’s margin.
The cut piece is heavier, and that is a separate problem
Density does not stop being relevant once the cut is finished. A severed hardwood stem or a lifted hardwood stump is heavier per metre than the softwood equivalent of the same diameter, and the attachment is still holding it. That moves the limiting factor from the cutting head to the carrier, which is why the lift chart and attachment mass guide insists that a cutting capacity is never a suspended-load capacity. Extracted stumps compound the problem by carrying soil and stone as well as timber. The practical result is that the safe piece length in hardwood is shorter than an operator used to lighter material will assume, and that more, smaller cuts are often the faster method.
Why brochure and video figures mislead
A demonstration video is not dishonest because it shows a head performing well. It misleads because everything outside the frame has been optimised: a well-matched carrier at the top of its flow band, fresh tooling, dry accessible ground, straight stems and, very often, plantation softwood. Published diameters are usually determined under controlled conditions on material that suits the tool. None of that is transferable to a stand of mixed regrowth with butt swell, embedded fencing wire and forty-year-old dead limbs.
The specific claims to distrust are stems per hour, stumps per hour, hectares per hour, blade or tooth life, and any statement that a maximum diameter can be worked continuously. Those are the numbers that go into a tender and decide whether the job makes money, and they are exactly the numbers a supplier cannot honestly guarantee for a site they have not seen.
Establish your own figures rather than borrowing anyone’s
The most useful thing a buyer can do is build a small internal dataset for the species and sites they actually work. Green density is simple to establish if you can weigh a measured piece, and it converts diameter into mass for the rest of the project.
Cut a straight section, measure diameter and length, weigh it on a platform or weighbridge, and repeat across three or four representative stems. Illustrative method only; record the result against species, date and location.
Do the same for difficulty rather than diameter alone. Classify stumps and stems into bands (clean regrowth, normal mixed, dense hardwood with heavy root flare, rocky or contaminated) and record cycle times by band. After a few hundred cycles you will have something no brochure can give you: a production figure that belongs to your species, your carrier and your operators, and that feeds directly into building a tender rate and the cost per unit calculator.
Variability is as important as the average
Hardwood is not one material, and three kinds of variation matter commercially.
Between species, the spread is wide. Acacia, the ashes, the boxes and the ironbarks behave differently enough that a rate built on one can be badly wrong on another. A contractor moving between river red gum flats and a stringybark ridge is changing material, not just location.
Between green and dead timber, the change is dramatic in both directions. Green hardwood is heavier and tougher to shear but cuts relatively cleanly. Standing dead and long-fallen hardwood is lighter but often much harder, more abrasive and more prone to shattering, splintering or trapping a blade. Dead stems and old stumps also carry embedded grit, and they are the material that destroys tooling fastest. See wear parts to price before you buy for how to put a number on that.
Between coastal and inland stands, the difference is growth rate and form. Higher-rainfall coastal growth tends toward taller, straighter stems with less butt flare; drier inland stands tend toward slower growth, denser wood, heavier flare and more branch structure low on the trunk. Dust and soil abrasion are generally worse inland, and that shifts the blades versus carbide teeth decision on a mulcher.
How to demand a hardwood demonstration
A demonstration is only evidence if it is run on your material. Ask for it as a structured trial rather than a showing, and say in advance what will be recorded.
- Nominate site and species
- Fit to your carrieror a documented equivalent
- Run a measured block
- Record by diameter band
- Inspect tooling after
Insist on four things. The material must be the species and diameter mix you work in, including the awkward end of it, not the easiest corner of the block. The carrier must be your machine, or a machine whose auxiliary flow, pressure and cooling are documented and comparable. The trial must run long enough for oil temperature to stabilise, which on a continuous-duty attachment means at least an hour of steady work in ambient conditions similar to your season; see hydraulic cooling and heat. And the tooling must be inspected and photographed before and after, because tool condition at the end of the trial is the only honest indicator of wear cost.
Record, per diameter band: cycle or cut time, stems or stumps completed, the percentage requiring a second attempt or another method, fuel consumed, oil temperature over time, and the condition of blades, teeth, chain or screw at the finish. Photograph the finish standard as well, because a client’s idea of an acceptable mulch finish is a contract variable in its own right.
Confirm before ordering
- The species, diameter mix and moisture condition used to produce any performance figure you have been quoted
- Whether the quoted maximum diameter is a continuous production figure in hardwood, in writing
- Expected blade, tooth, chain or screw life in your dominant species, stated as a range with the assumptions behind it
- A demonstration on your material, on your carrier or a documented equivalent, long enough for oil temperature to stabilise
- Tooling condition photographed before and after the demonstration
- Cycle times recorded by diameter band and difficulty class rather than as a single average
- Your own measured green density for the species being cleared, and the piece mass it implies at working radius
- Wear-part pricing and lead times for the tooling that the demonstration actually consumed
Frequently asked questions
Is there a published density table I can use for Australian species?
Density figures for Australian timbers are published in forest-products literature, but they vary by provenance, age, moisture and whether the figure is green or air-dry, and a single table value is a poor basis for a tender. Measure a few representative billets from your own sites and record the result against species and location. That number will be more useful than any general table.
Does hardwood mean I should buy a bigger attachment?
Not automatically. Buying larger raises attachment mass, reduces carrier lift capacity at radius and can slow the cycle on the small stems that make up most of the work. The usual answer is to size on the dominant diameter, confirm the carrier can supply flow and pressure under load, and plan a separate method for the oversize minority.
Will carbide teeth always outlast blades in hardwood?
Tooling choice is driven more by contamination than by timber density. Rock, soil contact and embedded debris favour carbide durability; clean elevated woody material can favour blades for cut quality and speed. Dense hardwood raises the power demand for both, so the decision should follow the ground conditions on your sites.
How long should a hardwood demonstration run?
Long enough to be representative rather than impressive. For a cyclic attachment such as a shear or grapple saw, enough cycles to cover each diameter band you work in. For a continuous-duty attachment such as a mulcher or stump grinder, at least an hour of uninterrupted work so oil temperature, rotor recovery and tool wear all show themselves.
The supplier says the attachment is used successfully in hardwood overseas. Is that reassuring?
It is worth hearing, but ask which hardwoods and in what condition. Northern-hemisphere hardwoods are generally less dense than mature eucalypt and rarely carry the same interlocked grain. The useful evidence is a trial in your own species, or a reference operation working comparable material in Australia.
Does dead standing timber count as easier work?
It is lighter to handle but frequently harder and far more abrasive to cut, and it is more likely to shatter or trap a blade. Price dead and long-fallen material as its own difficulty class, with a separate allowance for tooling.
Get a recommendation, not just a price
Send us your excavator model, hydraulic figures, tree species and typical diameters. We will come back with a carrier-matched configuration and a written specification you can compare against any other quote.