We’ve been great fans of inline electric demolition hammers in the 25-pound weight class since we bought two model D25900K DeWalts in 2003. The well-balanced tools are tall enough to use upright, yet light enough to hold diagonally for floor scraping or horizontally for vertical surface work. Skip forward to 2014, though, and we couldn’t buy replacement parts to keep our DeWalts alive. After researching the field, we decided to replace them with Bosch’s SDS-Max model DH1020VC, which hit the market in 2013. After using it for almost nine months, we have no regrets.
The Bosch DH1020VC delivers soft starts and a constant speed under varying loads, has a variable-speed dial to adjust the speed and impact force for maximum control, and has a “Service Minder” light indicating that the carbon brushes must be replaced within eight hours or the tool will automatically shut down. Bits can rotate and lock into 12 different positions, and the side handle adjusts for an optimal grip.
Similar to other demo hammers, this one uses a piston to launch a free-floating striker through a hammer tube, which in turn whacks an impact bolt against the bit. An air space between the piston and the striker compresses and drives the striker forward as the piston advances, then sucks it back as the piston withdraws. The air space also acts as a shock absorber. According to Bosch, however, the DH1020VC has a longer hammer tube, air space, and impact bolt than its predecessor to deliver more power to the bit while more effectively dampening vibration. A decoupled rear handle further reduces vibration.
ON THE JOB
When we first unboxed the Bosch, we saw that the case is smaller than our DeWalt ones, with less room for accessories. That’s a good thing, because we were no longer tempted to lug around an extra 20 pounds of steel along with the tool.
The first time we used the Bosch, it demolished all of our doubts about buying it. It broke up exposed-aggregate concrete with a high quartz content as if it were asphalt. We often install new columns in existing basements, and we’ve been using the Bosch to break up patches of the old concrete slabs and to excavate underneath to accommodate new footings. The tool has excelled at both tasks.
In fact, we often use a demo hammer equipped with a clay spade to break up compacted clay-laden soil for foundation pads and the like. Our old DeWalts could handle this job, but the Bosch cuts through the hard ground like a hot knife through butter. Granted, the Bosch is at least one generation above our DeWalts, but the difference between the tools is astonishing. We also used the Bosch horizontally for deconstructing a CMU wall and for opening up an old stone foundation. Superb.
As for vibration control, our hands typically begin to ache after using the Bosch continuously for about an hour. With our old DeWalts, that took only about 10 minutes.
THE BOTTOM LINE
If we had to demolish a whole basement slab, we would rent a heavyweight breaker like the electric 63-pound Bosch Brute or a 90-pound pneumatic. But the muscular 25-pound Bosch DH1020VC can handle most of our demolition tasks, and it’s light enough to use for horizontal or vertical work. As for comfort and power, it’s light-years ahead of our 12-year-old, 22-pound DeWalt models that it has replaced.
Josh Dunlap is a production manager of Aleto Construction Group, a residential design/build remodeling contractor in St. Louis.