What Is A Hammer Drill?

An overview of what is a hammer drill, types of hammer drills and its applications. 

Although a hammer drill has got little to do with woodworking, (it is mostly used for masonry work), we thought we must mention what is a hammer drill anyway. However, if you are using the hammer drill for woodworking purposes make sure that the speed can be varied right down.

So a hammer drill is known by several names, such as a rotary drill, rotary hammer, hammering drill or roto-drill. Basically, it is a rotary or turning drill which works with a hammering action. The hammering action gives a short and quick push to crush brittle material and enable drilling with less effort and quickly. A hammer drill is electrically connected and also runs on batteries.

What is a hammer drill

Types of hammer drills

There are primarily two types of hammer drills, the cam action type and the electro-pneumatic type.

Cam-Action (Percussion) hammer drills:

Drills with lower power units are known as hammer drills and have a percussion hammering method or cam-action. Here, two sets of gears with teeth interact with each other mechanically to hammer while turning the drill bit. In these drills, the chuck works by moving forwards and backwards on the rotary axis and the motion is secured with the chuck’s rotation.

It’s common to see this kind of drill used either with the hammer action or without. However, using just the hammer action is not possible as the hammer motion is caused due to the rotation on the cams. Such units are smaller and run on modern-day cordless technology. These are used more for drilling masonry or concrete occasionally.


Rotary hammers are the more modern power units. They are larger and have a much larger impact force because they harness a technology known as “electro-pneumatic” (EP) hammering mechanism,” since it runs on electricity rather than a separate air compressor. It comprises two pistons—a flying piston and a drive piston. Modern rotary hammers and those jackhammers that run on electricity use this technology. In modern units, the rotation and hammer functions can either be used together or singly. These drills are largely used for masonry work.

Dedicated hammer drill:

Also called a rotary hammer, this tool is used by masons for drilling concrete.

Corded drill with hammer option:

This kind of drill comes with a hammer setting. It runs on electricity, so you needn’t worry about charging batteries.

Cordless drill with hammer option:

These drills are best used in the absence of electricity at the work site.

Uses of hammer drills:

Hammer drills are used in those situations where workers need to get the maximum out of a standard rotary drill and a more powerful hammer drill. The unit comes with a switch that can switch off the hammering motion when not required. The chuck will therefore stay stationary when used for conventional drilling jobs.

When workers are not sure of the kind of surfaces they are going to be working with, using a hammer drill is a convenient and safe option. Hammer drills give buyers the option of choosing the power corded version or the battery-operated ones.

Cautionary tips:

Before using a hammer drill, bear these few tips in mind:

  • Wear protective eye wear so that you don’t get any dust into your eyes while you drill.
  • Use the appropriate drill bit for your specific drill.
  • Since the bit is usually hot immediately after use, do not touch it until it cools.
  • Read the literature that accompanies your drill before you use it initially.

The hammer drill is different from an impact driver. You can read more about the difference between these two tools over here.

Author: John Clax

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