FSI ST 20B Petrol stump grinder

FSI ST 20B Petrol stump grinder - image: HW
FSI ST 20B Petrol stump grinder - image: HW

If you hate the jiggling required by some small pedestrian stump grinders, then you have to try this one. It is well built but, crucially, it has a turntable that makes sweeping the stump a breeze. No operator force is required - and it's got agility.

Using the two independent brakes, the machine is wheeled down the ramp from the trailer and parked next to a small stump. It is easy to move - in fact, by releasing the brakes alternately it is possible to "walk" the unit up steep inclines and even climb steps to gain access to awkwardly positioned stumps.

This grinder has a Honda engine, so no trouble there - they are one of the most reliable petrol engines available. But it is the turntable that sets this model apart. It means that the wheels do not move at all. Instead, the top of the machine slews effortlessly on roller bearings. Every ounce of force goes into the stump and in next to no time the small stump has gone and we move on to a more serious challenge - a larger, rock-hard yew stump.

"I've used fixed-wheel machines before and this one is a lot less labour-intensive, definitely an improvement," notes Bryce with a smile. "I also like the throttle on the handle. You just pick it up from the work position."

The anti-vibration mounts on the handle work well to protect the user's hands from the worst of the shaking. Handlebars are height adjustable so, as you are working the wheel into the ground, a comfortable work position is maintained for the operator. What's more, this machine has a centrifugal clutch so the cutting wheel stops but the engine carries on running when the handle is released. That's handy. You don't have to restart the engine every time you reposition the machine or want to take a closer look at your work.

Built-in slinging points should make it easy to transport this unit between sites. Maintenance also looks simple, with grease points easily accessible. There are two standard V-belts with tensioners while the long arm of the machine means much of the debris is kept away from the engine for longer filter life. The green teeth have three flats on them so they can be slackened off, turned a third and then tightened up to present a fresh cutting edge.

"I like the fact that the teeth can be turned and this one also has a good-sized fuel tank so you are not stopping to fill it every 20 minutes," notes Bryce. In fact, it should be possible to get three hours of use out of one tank of petrol

Townsend finds the ST 20B lightweight, well balanced and easy to use. "It is simple. Anyone could operate it," he suggests. With that in mind, we reckon this stump grinder should prove a winner in hire shops as well as with landscapers and garden contractors.


Engine Honda GX390 13hp (9.5kW) - petrol
Fuel tank 6.1 litresCutting disc 370mm diameter
Teeth Eight (20.5mm diameter)
Sweep 80cm
Dimensions LxWxH: 1.8x0.7x1.1m
Weight 125kg
List price £4,300 + VAT (including twin wheels, LEDs and lifting points)
Tel Spectrum Plant - 0845 345 4866

Tested This Issue

FSI ST 20B Petrol

FSI D30-470

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:


01778 346222

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.


01789 414871

For 30hp tractors, the Gandini PTO-driven stump grinder has 18 teeth on a 50cm-diameter wheel. The working depth is 60cm.


01420 476248

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.


01257 260442

Geko manufactures the Stump Beaver for use on micro and mini excavators.


01636 594360

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.


01386 834813

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.


01403 820818

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.


01892 890364

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.


01270 723444

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".


01444 247689

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.


01977 623600

Universal offers a range of machines for attaching to suitable tool carriers and backhoes.


01933 274400

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.


01258 859100

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.

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