How pros drill through masonry

When it comes to drilling holes in concrete, concrete blocks, stone and other masonry, using a standard drill can be a real exercise in futility. The rotary motion of the drill bit -- even a carbide-tipped masonry bit -- is simply not sufficient to power through tough masonry surfaces.

Instead, you need a drill that combines rotation with an in-and-out hammering motion. This combined action helps to break down the masonry as the bit advances, making for much faster drilling without burning the bit. There are two basic types of drills that offer this rotational and hammering combination: the hammer drill and the rotary hammer. The two tools are often confused, but there is a definite difference between them.

Hammer drills

A hammer drill looks very much like a standard drill, and is available in both corded and cordless versions. Hammer drills have a heavy-duty keyed or keyless chuck, and will accept standard drill bits and screwdriver bits in addition to carbide-tipped masonry bits. They tend to be a little less powerful than a dedicated rotary hammer, but since they can be used for both hammer drilling and conventional drilling and driving, they are more versatile.

Like everything else in the tool world, you get what you pay for. Some lower-end hammer drills, especially cordless ones, are frustratingly short on hammering power, and their inexpensive construction makes for a short life span. So if you're considering investing in a hammer-drill/drill/driver combination, look for one with the quality, durability and features that will allow it to do all three tasks well.

One example of a high-end cordless hammer drill/drill/driver is the DeWalt DC927KL ($349). DeWalt is well known for high-quality tools that are designed with the needs of professional contractors in mind, so this is definitely a drill that will meet and exceed everything that the home handyman is looking for.

The DeWalt Hammer Drill uses their new 18-volt nanophosphate lithium ion batteries for more durability and longer life. To handle the stress of the hammering action it's a little heavier and more ruggedly built than a conventional cordless drill, but DeWalt has added a rubberized, non-slip grip for comfort.

The DC927 also has an all-metal, 3-speed transmission that lets you match the speed of the drill to the type of work you're doing. By turning a simple mode selector collar, you can choose the appropriate speed for hammer-drilling, conventional drilling or driving fasteners. ...CONTINUED

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