Do It Yourself Tips: What Are Percussion And Hammer Drills?

How hammer or percussion drills work, how they can greatly increase your productivityand guildlines for choosing electric or pneumatics.

Any hole can be drilled in concrete the old-fashioned way. Pound the end of a long iron

hand-held bit with a three-pound hammer and then blow the dust and debris out of the

hole. A hammer or percussion drill can do the same job--but fifty thousand times faster!

A hammer drill is a power tool that contains a turning spindle shaft and two internal

geared disks turning against each other to produce a pulsing hammer action. This

hammering action cuts into and pulverizes stone, concrete or other masonry material by

hammering a bit into the bottom of a hole up to 50,000 hammer beats per minute (BPM).

The hammering action and the rotary motion of the drill pulverizes material into dust and

debris that is ejected up along the spiral shaft of the masonry bit.

Hammer drills are available in electric and pneumatic models, re-engineered versions of

industrial tools. Sizes range from 3/8" to 1 9/16" at your local home center. Costs for

hammer drills are available in general ranges including corded electrics from $60 - $750,

cordless models $50 - $459 and pneumatics $50 - $370.

The advantage of electric hammer drills is that they can operate as a conventional drill

with the twist of a dial. Battery packs allow cordless portability. The downside to electrics

is they tend to run hotter and require an electrical power source that can limit operations

especially in wet conditions.

Pneumatic drills offer advantages. They tend to last longer because they run cooler than

electrics and cordless drills with no risk of electric shock. Repairs are generally easier

because they have fewer moving parts. Their lighter weight is less fatiguing.

As with all power tools, choosing the right tool for you is a matter of matching the right

tool for the job. How much power do you need? A good rule of thumb is buy what you

need now with an eye to the future. Visit your local home center and judge the comfort

and feel of several brands for yourself. Note location of controls like the forward/reverse

switch, trigger lock and speed control.

For electrics check for types of chucks. Keyless chucks tend to lose their grip and wear

out faster over time. For pneumatics, check for the type of disconnect. Quick disconnects

allow a quick change of tool or a fast disconnect of an air hose versus the slower

disengagement pressure release type.

Accessories that make the job easier include auxiliary handles usually located on the side

of the drill that allow a two-handed grip. Drilling holes in masonry requires that the drill

be held perpendicular to the material or the bit will bind which can torque the drill in the

direction of rotation. A solid handle can help you to prevent this or get back on the beam

should the bit shift.

Another good accessory is a depth stop attachment. It is difficult to see how deep you are

drilling a hole through the cloud of dust and debris ejecting from the hole. The depth stop

gives you the correct depth of the hole you need, essential for drilling a series of

consistent holes to the same depth, useful for installing an iron handrail on a concrete


Don't forget that electrics will need a good extension cord connected to a power source or

portable generator. Pneumatics require a compressor and a rated hose. Match the choice

of each by reading the manufacturer's guidelines for maximum length of extension cord

or psi (pounds per square inch) rating for the compressor hose.

Essential safety gear are goggles or face shields, dust masks, hearing protectors, gloves

and steel-toed shoes or boots or attachable toe shields.

Still unsure of what you want or need? Try a test drive of the tool by renting a hammer

drill before you buy.

© High Speed Ventures 2011