Hammer Drill Basics

Hammer drills are indispensable tools for both DIY enthusiasts and professionals, capable of drilling even the toughest masonry and concrete.

This power tool combines the rotary motion of a regular drill with the impact force of a hammering mechanism.

In this guide, we’ll delve into the mechanics of hammer drills, explore their types and applications, and help you understand why you need one in your toolkit.

What is a Hammer Drill and the Mechanics Behind It?

A hammer drill is a power tool that combines the rotary action of a regular drill with a pulsating hammering mechanism. While the drill rotates to cut through the material, the hammering action along the drilling direction ensures deeper and quicker penetration, especially into tough surfaces.

Picture a small yet powerful hammer continuously propelling the drill bit forward as it rotates. This gives you a rough idea of how a hammer drill works and where the name comes from.

Regular Drill vs Hammer Drill

Unlike regular power drills, which rely solely on a rapid spinning motion from an internal motor, hammer drills incorporate an additional hammering force, setting them apart.

The rapid spinning motion gives the drill bit the power to bore through materials like wood. A hammer drill does not “bore” its way through materials. Instead, the little hammer motion essentially pulverizes whatever is in front of the drill bit. But, the pulverization is just contained enough that the entire material is not damaged; only the section that you are drilling through is affected.

Working Principle: How Do Hammer Drills Work?

There are two ways to power a hammer drill. The first method is through percussion. Percussion hammer drills work by having a series of gears interact with each other.

Two ridged discs that are riding over each other produce a rapid hammering movement. The combined action of the gears rotates the drill bit, while at the same time hammering the drill bit forward.

Another method of powering hammer drills is through electro-pneumatic power (EP for short).  This is mainly used in rotary hammers.
EP hammer drills, as you can probably guess from the two names, are powered using a mixture of electricity and pressurized air. The mechanism consists of a guide cylinder, drive piston or exciter piston and flying piston. Electric power is used to rotate the crank which in turn moves the drive piston. While the compressed air creates a pressurized air cushion between the pistons, which then give the drill its pulverization power.

*Related Info: An impact drill is a different power tool. See the difference between hammer drill vs impact drill /driver here.

Types of Hammer Drills

There are two main kinds of hammer drills that you need to be aware of. The first one, and more common kind are referred to as regular hammer drills. The second kind is known as “rotary hammers.” Here’s where things get intriguing with the terminology, so let me take a moment to clear it up.

Both regular hammer drills and rotary hammers are kinds of “hammer drills.” But rotary hammers are referred to by a different name because they fill a slightly different role, which you will learn about in this section.

Regular Hammer Drills

These are commonly referred to as hammer drills. The vast majority of regular hammer drills use the percussion power system that I described in the last section. That means that they are easily able to pulverize tough materials like concrete or brick quickly and efficiently.
The regular hammer drill is sufficient for most DIY and handyman work.

Regular hammer drills come in two sub-categories, corded models and cordless models. Each with its own set of advantages and disadvantages.

Corded Hammer Drills

I am pretty sure that everyone knows how corded power tools work at this point. You plug them in and use them. On the plus side, corded hammer drills tend to be more powerful than their cordless counterparts are. The reason for this is that corded models have a constant source of power since they are plugged in. This enables corded hammer drills to have a noticeably higher RPM (revolutions per minute) and just more overall power.

They also tend to weigh less and are less expensive when compared to the cordless version.

However, they do have one noticeable downside, which is that they lack the mobility of cordless models. You need to either use extension cords or hope that the area you are working at has a lot of conveniently placed outlets. In my opinion, corded hammer drills are a better option, but I do have to admit that having less mobility can become quite annoying.

Cordless Hammer Drills

The Cordless hammer drill works by making use of an internal battery, which needs to be charged regularly. Now, as I said above, the main advantage you get from using a cordless model is portability. If you are working on a large job site then the added mobility of a cordless hammer drill will be very useful.

Additionally, I often find that the cord is a hindrance when working in tight spaces. A cordless hammer drill offers the convenience of portability as well as ease of use.

However, that mobility comes at a price. The fact that it runs on battery power means that the cordless hammer drill simply cannot deliver as much power as a corded model for a longer period of time.

Rotary Hammers

Rotary hammers or rotary hammer drills are essentially more powerful corded hammer drills.  The rotary hammers use the EP (electro-pneumatic) power system that I described in the first part of the article. This means that in terms of pure power, rotary hammers outclass regular corded hammer drills.

Another key difference is that rotary hammer drills come with a hammer-only mode. Usually, these tools have 3 mode settings; drill only, drill with hammering action, and hammer only. You can also use a rotary hammer as a mini jackhammer.

Generally unless you a professional; a rotary hammer simply will not be useful enough for you. If you are a DIYer, consider renting one instead of buying it, you will save money.

Hammer Drill vs. Rotary Hammer: A Comparison

Both hammers drills and rotary hammer drills work on the same principle. However, they have some key differences.

*Compared to 3 jaw chucks, Slotted Drive System or SDS chucks are more suitable for hammering. Most rotary hammers come with SDS chucks and hence they are also known as SDS drills.

Here is a video that shows the practical use of the tools. See the performance difference between a hammer drill and a rotary hammer.

Hammer Drill Uses

There are many home improvement projects that end up requiring you to drill through concrete or masonry. For example, say that you want to hang something in front of your house. In order to do that, you are going to need to find a way to drill through masonry (this is assuming that the front of your house is made of brick, of course). A regular drill will either break or get burned out very quickly if you try to use it on masonry. So, what is a homeowner to do?

Well, you could use a masonry drill bit on your cordless drill if it is a light job. However, there are specialty tools out there designed to help DIYers and professionals alike to get through masonry and concrete in no time.

A hammer drill has a very specific use, which is drilling through masonry and concrete. You can use regular drills for that job, but it will take longer and less efficient. You use a hammer drill when you have to drill 40 holes into concrete in a single day. This makes them useful for a wide variety of home renovation projects. A common misconception is that hammer drills are for hammering in nails. That is not the purpose of a hammer drill, and if you use it that way, then you are using the tool incorrectly.

Conclusion

This is everything that you need to know about hammer drills. They are useful tools to keep around the house. If you ever find yourself needing to drill through difficult material, then a hammer drill is your best option. I definitely recommend that everyone keep one in their tool shed.