Powered by a water-cooled 30hp Kubota diesel engine, this solidly built machine boasts a sweep of 1.35m - that's more than 4ft - and can grind to a depth of 38cm. We are expecting great things of it. What we learn is the value of selecting the right teeth for the material being cut.
First, we try to finish off the challenging yew. The machine feels somewhat underpowered. "To be honest, I expected it to be quite a big jump up. But it doesn't feel as if it is," says Townsend. The wheel carries the same teeth and pocket set-up as the smaller ST 20B.
We move on to a tree of heaven (Alianthus altissima) that is sticking 18in or more out of the ground. This time, the stump is decimated - and quickly. That's more like it.
Being water-cooled, and Kubota, the engine makes the machine more suitable for urban areas, while a set of work lights could be used to finish a job off on a winter's afternoon. Good positioning of the exhaust keeps fumes away from the operator.
The twin wheels drop off with a single bolt to reduce the width to 80cm for accessing gateways. The control panel has four levers - steering on the first, then forward and reverse, up and down on the third and finally sweep control. There is also a speed restrictor and a diff lock to get the machine out of tricky, slippery situations. Tractor-type wheels are also available for more demanding terrains.
Although the control panel swings out to enhance the view to the wheel, Townsend, who is tall, has difficulty seeing the point of contact. He has to quickly learn to "feel" the bite. "It's a neat machine, quite compact, but I still have to peer round the guards to see the wheel working," he says. But he quickly masters the controls and adds that he would like to see a tracked version.
The D30-470 has a generous-sized fuel tank - holding sufficient fuel for up to 10 hours - and lifting/lash-down points for transport. Grease points are obvious and accessible. There are two V-belts and an electric clutch. A storage compartment should prove handy for spare teeth and spanners.
Engine Kubota 30hp (21.7kW) - water-cooled, three cylinder, diesel
Fuel tank 35 litres
Cutting disc 470mm diameter
Teeth 18 (20.5mm diameter)
Dimensions LxWxH: 2.7x0.8x1.6m
List price £15,750 + VAT (Kohler petrol version offered for £12,950)
Tel Spectrum Plant - 0845 345 4866
Tested This Issue
FSI ST 20B Petrol
FSI D67-720 4WD
The Review Panel
Andy Bryce, arborist, Westonbirt Arboretum
Richard Townsend, tree team operations supervisor, Westonbirt Arboretum
For more than a decade, Danish firm FSI Powertech has been 100 per cent focused on developing, building, testing and selling stump grinders and cutters. During that time, the company's machinery - from pedestrian and remote-controlled models to units for attaching to tractors or excavators - has acquired a reputation for performance, durability and operator friendliness. Not surprisingly then, we wanted to test it.
Last summer, Spectrum Plant was appointed sole UK importer and launched the FSI range at the Arb Show, held near Cirencester in June 2013. As soon as the machines were available, we asked for a trailer-load to be delivered to the National Arboretum at Westonbirt, where Forestry Commission staff put the units to work.
The arboretum, in a picturesque Gloucestershire landscape, is managed by the Forestry Commission and supported by the Friends of Westonbirt Arboretum. Begun by wealthy Victorian landowner Robert Holford in the 1850s, it is now internationally important and contains 14,902 labelled trees from Britain, China, North America, Japan, Chile and other temperate climates. It attracts more than 350,000 visitors each year. On the day of the test, the weather was warm and sunny.
Stump grinder supplier listings and contact details - see whatkit.co.uk
The following is a list of suppliers of pedestrian as well as tractorand excavator-mounted stump grinders. Omission of any company or product does not imply criticism:
Driven by a power take-off (PTO), the SG100 is suitable for 20-45hp tractors with one double-acting spool valve. Low-cost replacement teeth are fitted to the 35cm-diameter wheel. A three-point linkage quick hook-up frame allows easy fitting. List price: £5,950 + VAT.
020 8723 0161
Bobcat offers three stump grinders with working depths from 27.9cm to 38.1cm for fitting to skidsteer loaders.
For 30hp tractors, the Gandini PTO-driven stump grinder has 18 teeth on a 50cm-diameter wheel. The working depth is 60cm.
Four pedestrian models provide engine options of 13hp or 15hp Honda, or 27hp or 30hp Kohler. All the machines have eight teeth on 36cm-diameter wheels. Working depth is 21cm for the Honda models or 41cm for the Kohler-powered units.
Geko manufactures the Stump Beaver for use on micro and mini excavators.
GLOBAL RECYCLING SOLUTIONS
Global supplies the Bandit brand in the UK. Pedestrian and remote-controlled hydraulic models start with the HB19 13hp manual unit and include 27hp pedestrian and sidewinder machines as well as 45hp and 61hp remotely operated models. Bandit 2800XP is a tractor-mounted version requiring 60hp from the tractor. Tracked stump grinders and units for skidsteers are also available.
Four-wheeled and self-propelled stump grinders are powered by 27hp engines, while the larger FZ560T is a PTO-driven model requiring 50hp and having 18 teeth on a 60cm-diameter wheel. The basic PTO model costs £7,400 + VAT. A remote-controlled version is available for £9,000. The working depth is 60cm.
0844 243 5263
The SG13 is powered by an 11.7hp Honda engine and has just three teeth on a 35.6cm wheel. Cutting teeth available for various soil conditions feature three independent edges to triple the use of each tooth by rotating it using a 9/16in wrench. Grinding is to a 30cm depth.
JBM MACHINES (RICHARD COURT FORESTRY ENGINEERING)
With a 13hp Honda engine, the 2913 is the smallest JBM stump grinder and has 18 teeth on a 30cm-diameter wheel. Powered by a 60hp Kubota diesel engine, the 5960 has a 51cm wheel. A tractor-mounted version with 66cm wheel is designed for tractors of 70hp upwards and works to a depth of 60cm. List price of the latter is £15,860 + VAT.
Seppi Star stump grinders are designed for use with 80hp tractors.
0191 236 7795
The wide range of Carlton stump grinders supplied by Orange Plant includes pedestrian models from 13hp upwards. Machines operated by remote control are offered with 99hp and 140hp engines. There are also models for use with tractors providing upwards of 45hp.
0845 402 1756
The range of stump grinders designed and manufactured by Predator continues to grow and now includes pedestrian models of 12hp, 25hp, 27hp, 28hp and 50hp. Remote models are powered by 28hp, 50hp and 75hp engines.
0845 345 4866
In addition to the machines tested (see p35-36), Spectrum also offers FSI Powertech's stump grinders for use with tractors, excavators and side arms.
The latest range of stump grinders available from Toro includes the STX26 dedicated tracked machine with transport speeds of more than 6kmph. The hydraulically driven heads of Toro grinders mean there are no belts to break, slip or require tensioning. The head also features a built-in braking system, while the exclusive Quadrablade tooth design cuts like a router without "pulling the operator into the stump".
The Camon C500 is a compact stump grinder powered by a 13hp Honda engine and having a 30cm-diameter wheel fitted with eight carbide teeth. At only 64cm wide, this machine easily passes through garden gates. The maximum working depth is 33cm. List price: £3,295 + VAT.
Universal offers a range of machines for attaching to suitable tool carriers and backhoes.
Vermeer offers Jo Beau tracked stump grinders with 13hp or 31hp engines. Vermeer-branded models include 13hp and 31hp petrol units. Model SC372 has a 37.8hp Yanmar diesel engine and boasts auto-seep and yellow-jacket teeth for serious grinding. The SC60TX has a 60hp diesel engine yet is only 88cm wide. The SC652 has a 65hp Cummings engine and four-wheel drive while the range-topping SC852 is an 85hp machine with a maximum working depth of 63.5cm. New is the SC30TX tracked stump grinder with 27hp engine.
Westcon supplies Rayco-branded stump grinders with units powered by 13hp, 25hp or 35hp petrol engines, or 44hp, 67hp, 99hp or 140hp diesel engines. Various features are offered on the machines, such as a chassis for towing the RG140DXH.