What’s going on inside a rotary hammer drill?

 

Rotary hammer drills drill and demolish into masonry. They get inside any possible walls they can. But this time, let’s open a rotary hammer and get inside it to see what is going on. Have you ever wondered how a rotary hammer works? Well, they are more powerful than an impact drill and weaker than a demolition hammer (or a jackhammer). As you know, they combine the hammering function of the demolition hammer and also, the rotary function of a hammer drill. So, they work with three functions: drilling, hammering and hammering with rotation. Hammer drills or impact drills are equipped with 2 discs and a spring in between before their bit holders to create the hammering performance. But, the mechanism inside a rotary hammer drill is a whole another story. You would be surprised if I tell you that the hammering mechanism inside it, is caused by the air compression and its pressure to the bit holder. But how? In the following paragraphs, I am going through the inner and outer mechanism of a rotary hammer drill and after that I want to tell you about some differences between choosing a hammer drill (or an impact drill) and a rotary hammer. So, stay with me for the rest of this article.

The Inner Mechanism of Your Rotary Hammer Drill

All of the power tools have somehow the same mechanism inside when we talk about their electrical motor. They are usually equipped with a universal or an induction motor . Recently, the brushless motors  are taking place of the older motors and they are more efficient and higher in quality. However, their price is much higher than universal and induction motors. A rotary hammer is usually empowered with a motor which is at least 1000W or 1100W in power.

The story begins from the parts after the motor and these parts are the main factors of power tools like rotary hammers that turn the electrical energy to mechanical energy. Rotary hammer drills create their hammering action with the help of a piston that is driven by a crankshaft. This piston is ridden by this crankshaft inside a cylinder and the result of this mechanical movement is the air compression I talked about earlier. When the piston goes back and forth, the air pressure and its hits to the plate before the bit holder creates the hammering mechanism. Usually, the cylinder is made of a strong and high-resistance metal alloy and also, the piston and shaft are aluminum die-casted. The minimum impact energy in joules resulted from this mechanism is usually around 3J. This amount of energy can be maximum 10J in bigger and stronger rotary hammer drills.

The Outer Mechanism of Your Rotary Hammer Drill

Imagine its pull and push motion combined with the drilling function! It can result an amazing combination for all the drilling and hammer drilling functions and especially, the demolition. It is so poetic, isn’t it? 😁 Well, as I said before, the most common usage of this combination in rotary hammer drills is demolition, which requires digging or breaking down concrete walls. We talked about the mechanism inside rotary hammers and how their power comes from their powerful induction or universal motor and is transferred to the cylinder and piston. All the process inside them are controlled by their special switches outside. Usually they are controlled by a variable-speed trigger or a trigger equipped with a dimmer switch that can include a lock-on button for more convenience during continuous operations. The story becomes more interesting with the combination of the mode selection knob and the chiseling function selector. They are designed to control the three main functions of your rotary hammer drill which is what we also talked about before.

Another important point about the outer features of rotary hammers is the housing. High-quality models are usually equipped with die-cast magnesium body housing and an anti-vibration system to reduce the hits during operations. This system is placed between the handle and the main part which is the cylinder. The result of this body housing is superior heat dissipation, body strength and light weight that can lead to a “sweat-free” drilling time. And moreover, the anti-vibration system helps to reduce the hand fatigue and improves the efficiency during your work.

The bit holders should not be forgotten here. They are actually considered as one of the most important parts of a rotary hammer drill. There are two types of bit holders that are used for rotary hammers. SDS-plus and SDS-max bit holders are those parts you can put your chisel or bit inside them and do the demolition or drilling. SDS-max bit holders are usually used for rotary hammers that are more powerful and heavier. They are also used for demolition hammers too.

Hammer Drill vs. Rotary Hammer

They are both excellent for drilling any kinds of masonry. It is obvious that rotary hammers are more powerful and they have hammering-only function without any rotation. All rotary hammers have an SDS chuck for a better hammering function. It is clear that you can drill a hole inside a concrete wall with an impact or a hammer drill. But, when it comes to a bunch of holes to drill into an old and tough concrete wall, the difference becomes more impressive. It is exactly the mechanical function that separates these two power tools. In the introduction of this article, I said that what makes the impact action of a hammer drill. And you are completely aware of the mechanism of a rotary hammer (also known as a rotary hammer drill). Which one do you think is more powerful and resistant in continuous operations?

Rotary hammers bring a lot more impact energy than impact drills. They are much more durable and pros prefer more to work with them. Another advantageous feature is that almost all the rotary hammers have three functions: drilling, hammer drilling and hammering. So, they can play the role of a mini jackhammer too. A rotary hammer costs more than a hammer drill. Just choose the proper power tool you need by considering what you exactly want to do. A more powerful tool can be too much for you while by choosing a tool that doesn’t meet your desired needs, your expenses might double. So, make your choice wisely.