Those who use power tools often are confused about the difference between hammer drills and impact drills (or drivers). The principal differences are in purpose, appearance, weight, expense, and method of operation.
First, the two types of drills differ in purpose. A hammer drill can and usually should be used for drilling into a hard surface like brick or concrete, i.e., masonry. Some hammer drills do have a feature which allows the user to turn it back into a regular drill.
Video illustration of the workings of a HAMMER DRILL
In contrast, an impact driver is used mainly for driving in fasteners like screws and nails. It can also drill holes. It can drive nails through sheetrock if needed, and it can be used in any situation that requires a regular drill. An impact driver should not be used for woodworking since extra power may kick in at any time when needed by the fastener being employed, and damage the item being handled.
In appearance, the two drills differ dramatically. The impact drill (driver) is shorter and stubbier. It has a hexagonal socket in place of a chuck. It may hold an adapter into which bits may be attached. The hammer drill is heavy and large, like a small jackhammer. It has a drill chuck which can take different types of bits and sizes.
The hammer drill and impact driver differ in manner of operation. The hammer drill uses more pressure than an impact drill. When a person uses it, it feels like a hammer hitting very fast as it drives into the hard material. It is very loud too. A hammer drill vibrates in a back and forth motion. It has an adjustable clutch so that too much force is not applied.
An impact driver goes in a rotary fashion. It can seem like a cordless screw driver unless more power is needed. Then a special mechanism kicks in and provides more force. Usually an impact driver doesn't have an adjustable clutch to prevent too much power for a small job.
A buyer should think about purchasing a cordless hammer or impact drill instead of a corded tool. Cordless drills are much lighter. They can be used anywhere and thus are less restricting. There is never a cord in the way while the user is working. However, a buyer should get a second battery pack along with the cordless tool. This should be charging while the other is in use. The cordless types of drills can be just as powerful as the corded drills. More recent hammer drills may have lithium ion batteries for more power.
Video demonstration of How the Impact Driver works.
If expense is a factor, it should be noted that a hammer drill is more expensive than an impact driver. Sometimes, though, a hammer drill would be necessary for the tough drilling involved.
In summary, impact drills and hammer drills vary considerably. They vary in price, use, weight, appearance and method of operation. An impact drill is more practical for everyday home improvement projects. It would be a better choice if a buyer had to choose just one type of drill. Impact drills are smaller and less heavy and perform most of the functions a user would need.
Source : www.softschools.com