rotary hammerRotary Hammers are simply defined as rotary drills with a hammering action. In other words, they are handheld jackhammers. They are also known as hammer drills, roto-hammers, or impact drills. The fact that there are multiple terms for those drills lie in their internal mechanisms that pound the drill bit in and out while it is spinning. Lower-powered units are usually called “hammer drills” and are powered by a specially-designed clutch consisting of two ribbed metal discs that click in and out against one another. Higher-powered units are usually called “Rotary Hammers” and are powered by a piston mechanism that compresses a cylinder of air. But no matter what the mechanisms and names are, they are all used on masonry and other brittle materials; particularly for installing fixtures on walls made of brick, block, or concrete. The hammering action is expressed via BPM (blows per minute) or IPM (impacts per minute), and those drills operate at thousands of BPM on average.

The origin of the rotary hammer is unclear, as three entities claim that they developed these hammers first: James D. Smith in 1975, Hilti in 1967, and the Milwaukee Electric Tool Corporation in 1935.

What Are Rotary Hammers Best Used For?

Rotary Hammers, due to their larger sizes, are more suited for drilling bigger holes. They also have a switch or lever that enables switching between hammer mode and drill mode (some models have a third mode that combines the two functions). The switching lies in turning on or off the special hammer clutch. Due to the larger amount of force that they generate, typical masonry bits are made inadequate for them; since the shank would be forcibly removed from the tool’s chuck in a few seconds. Special shanks have been invented by various manufacturers to alleviate this problem. One example is Bosch’s SDS (Special Direct System) technology, in which a cylindrical shank is used, with indentations to be held by the chuck. Note that standard drill and power-driving bits do not work on SDS shanks.

The hammers can also be fitted with chiseled and pointed tool bits for pure pounding work. They also have an oil-filled gearbox that gives them durability in situations that require more force and generate more grit while working. The durability can last for 20 years with minimal repair service.

Besides masonry work, the hammers can also be used in situations wherein a conventional drill is not enough. For one thing, if you want a larger and cleaner hole, go for the hammer’s drill mode. This mode’s higher speed compared to the usual drill (3,000 rpm max versus 850 rpm max) helps.

Masonry Drill Bits Used In The Rotary Hammer

Masonry drill bits have deep flutes with chisel-pointed tips due to the general composition of all types of masonry when compared to metal, plastic, and wood. They are usually found in six-inch lengths (four- and five-inch bits are also available on the market) and have varieties that can fit either standard or SDS-type shanks. Like all other drill and tool bits, masonry bits degrade over time and must be replaced. Two signs of a worn bit are a smaller diameter near the tip and worn-out flutes. The ruined flutes can no longer lift out masonry dust of the hole, packing the dust inside it and jamming the bit. To free the stuck bit, keep lifting the hammer up and down while it is still running to remove the dust; or use vise grips or a Stillson type wrench. If the hammer has a reverse function, you are in luck.

Manufacturers roll out cordless versions of their power tools, and hammers are no exception. In early 2010, Milwaukee and Rockwell took the initiative and released cordless hammers that promise to deliver the same power as their corded brothers. However, the persistent problem of running out of power when using a cordless power tool haunts the cordless hammer; and it gets worse since a large amount of energy is used to deliver the drilling and pounding action. To be safe, buy both the corded and cordless versions.

Rotary Hammers are truly the power tools of choice for those who dabble in masonry. With their sheer power and multiple uses, busting through rocks to create holes or to chip away unneeded pieces has never been made easier.