Shopping for drills at the local hardware store often confuses the novice builder; tool departments stock power drills of varying power, size and capability. Two common types of drills, the "combi" or combination drill and the drill driver, have significantly different capabilities and applications. Become familiar with the differences between combi drills and drill drivers, and choose the right one for your project.
The drill driver performs fewer functions than the combination drill. As suggested by its name, the drill driver performs two functions: drilling and driving. "Drilling" refers to the act of boring holes, and "driving" refers to the act of fastening or driving screws. Outfitted with a sharpened drill bit, the drill driver bores holes through soft materials, such as wood and plastic, and metal. Outfitted with a driving bit, the drill driver drives any variety of fasteners, such as hex-head screws and Phillips-head screws. While the drill driver generally performs poorly at boring through masonry, such as concrete and brick, the combination drill performs this task well. The combination drill combines the capabilities of a drill driver with an added hammering feature; set on hammering mode, the combination drill's drill bit reciprocates back and forth in a hammering motion. The combination of hammering and rotary motion both cuts and drills through masonry surfaces, allowing a builder to create clean, large-diameter holes through concrete, brick and stucco.
Combination drills are generally larger than drill drivers; the size and weight of their internal mechanisms reflects the nature of their heavy-duty work. In contrast, drill drivers require relatively few internal mechanisms, and innovative manufacturers even offer pocket-sized models. Also, the combination drill's hammering motion typically requires a builder to grip the tool with two hands, whereas a builder can easily manipulate the average drill driver with a single hand. Another notable aspect of a drill's size is the length of its cord, or its lack of cord. Although both combination drills and drill drivers are available as cordless models, the drill driver's smaller size and lower energy requirements are well-suited to battery operation. As such, there are relatively few varieties of cordless combination drills compared to the overwhelming amount of cordless drill drivers.
As the savvy shopper might suspect, the extra-capable combination drill costs comparatively more than the average drill driver. However, a popular name-brand drill driver might cost double the price of an unknown, off-brand combination drill. If you plan on frequently drilling through masonry, the extra cost of a combination drill is well worth it.