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Market Report: Power Tools & Accessories Making an impact After testing DeWalt’s latest 9kg hammer drill, Phil Mist finds the product worthy of hirers’ attention. The 9kg class of rotary hammer drills is a market that was, until recently, comparatively overlooked by power tool manufacturers, but now this particular segment contains several excellent machines. Incorporating significant technological improvements, they offer better performance and increased safety features. The latest newcomers are three models from DeWalt. They were actually announced some time ago, but are only now arriving on dealers’ shelves. I tried out the highest specification model, the D25730, which weighs 9.5kg. The chief difference between the other two machines, the 7.8kg D25700 and the 8.3kg D25701, is their slightly reduced drilling capacity. Tests were conducted on a large block of concrete, of a hardness suitable for motorway bridge construction, representing a formidable challenge. The D25730 boasts an array of features, such as a torque limiting clutch, complete torque control, soft start and electronic speed and impact rate control. It has a vibration dampened main handle and DeWalt’s AVC (active vibration control) to reduce HAV, together with a 24-position front tool holder for chisel adjustment. Despite its weight, the tool handles extremely well. It feels well balanced, being very powerful yet smooth, even when drilling holes of up to 52mm in diameter. The soft start facilitates the initial part of a drilling operation, even for a novice. The active torque control always sets itself to the lower setting when the machine is switched off, so that it starts in the correct position for small to medium sized drilling operations. To drill very large holes it is necessary to manually switch the setting to the high position. The dampened rear handle, which rises and falls as pressure is applied, works well, provided the operator is competent. This, together with the AVC system, reduces the stated vibration level to a single dominant axis figure of 5.7m/s2 (measured in accordance with EN 50144) and a tri-axial figure of 11.4m/s2 (measured according to EN 60745). 11.4m/s2 is an excellent result for a machine of this size, weight and power. For performance, the D25730 is in a class of its own. Powered by a 1500watt motor, and having a variable single-blow energy rating of from 3-18J when using standard SDS-Max drill bits, the time taken to drill a large number of holes in various diameters was substantially less than when using several competitive machines. There was a saving of up to 30% in time taken to drill each hole compared with a 45mm capacity machine. In addition, it was possible to break a great deal of concrete in a much shorter time than when using other models in the breaking mode. The lock-on switch assists when chiselling or breaking for an extended period. Operating when the tool is set in the ‘hammer only’ mode, it is less tiring than having to keep a finger pressed tightly on a ‘dead-man’ type switch. Like all hammers, the D25730 is noisy, especially when breaking, as the chisel or point adds to the total of noise emitted. However, the tool is no noisier than similar products, but it out-performs them. At 105dB (A) sound power level, hearing protection is mandatory, as are eye and face protection. An amber or yellow service light operates when the brushes are in need of replacing. This is approximately eight hours before a red light illuminates, when the brushes are worn out (it also lights up if the machine is faulty). The wear time is said by DeWalt to be after approximately 150 hours’ use, but my experience tells me that, in reality, it will be nearer to 300 hours before the red light comes on. Overall, the D25730 is quite simply the best machine I have used in its class (so far), and it shows how far power tool technology has developed in recent years. • T
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339258 Executive Hire News › Archives › July 2006 › Market Report › Making an impact
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