Executive Hire News › Archives › December 2008 › Executive Report : Cutting it fine
Executive Report : Cutting it fine
Phil Mist, EHN's power tools specialist, tests Hilti's powerful new DCH 300 electric disc cutter.
The abrasive cutting off wheel or diamond blade fitted to any petrol powered disc cutter always rotates forwards and downwards, away from the operator, allowing most materials to be cut whilst pulling the machine gently backwards. Whenever a manufacturer has introduced an electric equivalent, the blade has always rotated in the opposite direction, meaning they are better suited for working away from the operator. The reason given is because of the sparks created when using a bonded abrasive cutting off wheel for cutting metal - a task less common in construction, which typically involves work with masonry and concrete.
Nevertheless, Hilti has just launched its DCH 300 electric disc cutter, which rotates in the same direction as all such previous machines. While not affecting performance, it does mean the tool can normally only be used working away from the operator. If used in a vertically downward position, the operator may have to adjust their footing as the machine travels forwards. It is also designed for right-handed people, with a front handle quite unlike those on petrol machines (it does not loop over the top).
EHN’s tests were carried out using a diamond blade on various cement blocks, masonry materials and concrete. When used without dust collection, the blade guard impressively deflected the dust downwards, away from the operator. Since the collection nozzle on top of the guard has a flip-up lid I assumed (wrongly) that it would fly open during operation causing dust to erupt and cover me, but it stayed down and the dust was deflected onto the base material. Admittedly, I was cutting vertically downwards. When connected to a suitable collection system, the result was virtually dust-free operation.
The 110V test machine had a 2300watt motor (the 230V version’s is 2,600watt) and comes with a yellow 32A plug. It is, therefore, necessary to use a 5kVA transformer or a generator with a similar output. Soft start means the DCH 300 does not wrench your arms out of their sockets, yet it offers immense reserves of power. A current limiter protects any fuses at start-up, and the switch arrangement has a safety interlock situated on top of the rear handle, which has to be pressed in before squeezing the trigger with your index finger.
The upper blade guard is substantial and its angle to the work surface is easily adjusted using the hexagon wrench supplied. There is also a telescopic lower guard, which is swung into position and locked by a simple button. A depth adjustment bracket is incorporated to set an accurate maximum depth of cut. Fitting a bonded abrasive cutting wheel or diamond blade requires the use of what is, quite simply, the largest spanner I have ever seen supplied with a portable tool. The test machine was accompanied by a diamond blade and a pair of 60mm-diameter flanges, but if fitting a bonded abrasive cutting off wheel, then 80mm versions, available from Hilti, must be used.
Running at a no-load spindle speed of 4,900 rpm, the edge speed of the blade is 77m/s, well inside the top UK limit for abrasive wheels of 80m/s. Cutting performance is impressive, with the sample diamond blade devouring the test materials. Sound pressure noise level is 106dB(A) and a service indicator light is standard on the UK specification machine. The DCH 300 looks a little strange, especially with the large lower blade guard in place, but it works exceptionally well. At 9.4kg it weighs virtually the same as petrol powered models, and Hilti quotes a low vibration emission figure of 5.1m/s2. Incidentally, you’ll need a large shelf for the machine: the carrying case is enormous. •
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