The evolution of the carbon brush and the electric motor – the heart of modern power tools
(Part I of the brushless motor power tool series)
When the motor not only spins, but also ‘thinks’
If a few decades ago someone had suggested that a compact drill-driver could ‘monitor’ its load, optimise its performance, and automatically conserve its battery, we would probably have smiled at the idea. The electric motor used to be a simple matter: electricity in – rotation out. Today, however, more and more power tools are fitted with “intelligent” drives, that is, brushless motors. But how did we get to this point? Why have we moved away from brushes, and what does this mean in practice?
Before we immerse ourselves in modern technology, it’s worth understanding where the development of the electric motor began – and why the brush was an indispensable element in every household and industrial machine for decades.
The classic carbon-brush motor: heir to the industrial revolution
The 19th Since the end of the 19th century, most small electric motors have operated on the commutator (DC) principle. The construction is simple, affordable, and highly scalable: it can be used in everything from small drills to vacuum cleaners.
A brief overview of how it works
At the heart of the carbon-brush motor are three main components:
- Stator: permanent magnets or electromagnets that create the magnetic field.
- Rotor: contains coils through which current passes.
- Commutator and carbon brushes: these ensure that current always flows in the correct direction through the rotor windings, enabling the motor to rotate continuously.
The carbon brush is a flexible component made of graphite that maintains continuous contact with the commutator as the rotor turns. It is through this that the rotor receives current.
(Diagram suggestion: cross-section of a classic DC motor, showing the carbon brush, commutator, rotor, and stator.)
The advantages of brushed motors – a simplicity that is hard to surpass
Although modern technology has advanced greatly, the carbon brush motor is still widely used in many areas today because:
- Simple and affordable: few components, easy to manufacture and maintain.
- Operates across a wide voltage range: from as low as 3 V up to 230 V.
- Easily adjustable speed: by altering the voltage.
- Strong starting torque: particularly useful when the machine starts under a heavy load (e.g. drill, angle grinder).
It’s no coincidence that until the early 2000s, almost every DIY tool was carbon brushed. Users would typically replace the brushes once a year if they wore out – and work would simply continue.
The problem with carbon brushes – a small component, a significant limitation
The disadvantages of carbon brushes have become increasingly apparent over time:
| Disadvantage | Technical explanation | Practical consequence |
|---|---|---|
| Wear | The constant friction between the carbon brush and the commutator results in material loss. | Over time, performance declines and sparking appears. |
| Maintenance requirement | The brushes need to be replaced periodically. | Dismantling, service costs, loss of time. |
| Sparking | A high-voltage micro-arc is created between the commutator and the brush. | Electromagnetic interference, overheating, fire hazard. |
| Efficiency loss | Friction and arcing produce heat. | Shorter operating time, higher energy consumption. |
| Limited speed | Due to mechanical limitations, it cannot be overspun. | Slower response, weaker dynamics. |
In the world of DIY tools, this meant that machines were heavier, hotter and less durable, especially in battery-operated mode.
The age of transition – when the motor ‘learned to think’
In the early 2010s, brushless technology began to appear in hand tools.
This was when it became possible to control the motor’s rotation not mechanically, but electronically – with the aid of a tiny microchip.
The commutator and carbon brushes were replaced by electronics: the rotor is a permanent magnet, and the stator’s coils receive the right amount of current at the right time, directed by a computer controller.
This development was revolutionary.
The motor was no longer merely a simple rotating machine, but an intelligent system operating with sensors and control algorithms, optimising its own efficiency.
Technological breakthrough – what makes the brushless motor so much better?
The operation of the brushless motor is fundamentally based on a different principle:
- The rotor houses a permanent magnet – no winding, no current transfer, no brushes.
- The coils placed in the stator are controlled by an electronic circuit (ESC – Electronic Speed Controller).
- With the help of Hall sensors or feedback voltage, the electronics always know exactly where the rotor is and when to ‘pull’ again.
This ‘digital commutation’ has eliminated the main limitations:
no friction, no sparking, no wear – in other words, less maintenance, greater efficiency, and a longer lifespan.
A Historical Overview – From Model Aviation to the DIY Workshop
Interestingly, the brushless motor did not originate in power tools.
It was the developments in model aviation and drone technology in the late 1990s that introduced it, as these fields required:
- low weight,
- high speeds,
- and outstanding efficiency.
As batteries (especially the lithium-ion types) advanced, the technology was adopted in hand tools.
From the mid-2010s onwards, most premium brands (Makita, Bosch, DeWalt, Milwaukee, etc.) have offered brushless models – at first at a premium, but nowadays increasingly within reach.
The Impact of Progress on DIY Culture
Brushless technology is more than just a technical innovation: it has transformed the DIY experience. The machines have become smaller, quieter, and more durable. The batteries last longer, and it is clear to users that brushless is not merely a ‘trend’, but the motor of the future.
The First Step in Evolution
The development of the electric motor points clearly in one direction:
mechanical solutions are increasingly being replaced by electronic intelligence.
The brushless motor is at the very centre of this evolution—a technology that both reduces losses and improves efficiency.
In the next part (Part II), we will take a detailed look:
- how exactly does a brushless motor work,
- what types are there,
- and with specific figures and examples, I will show why it is more durable and efficient.
TL;DR – Brief summary
(Open the arrow if you can´t see it!)
A revolution is taking place in the world of DIY tools: traditional carbon brush motors are slowly giving way to modern brushless technology. But what is the difference between the two, and why is a brushless motor worth it? In this article, we will introduce the development of electric motors, the advantages and disadvantages of carbon brushes, and the benefits you can gain from modern motors.
In this article, you can read about the following topics:
- The evolution of the carbon brush and the electric motor – the heart of modern power tools
- When the motor not only spins, but also ‘thinks’
- The classic carbon-brush motor: heir to the industrial revolution
- A brief overview of how it works
- The advantages of brushed motors – a simplicity that is hard to surpass
- The problem with carbon brushes – a small component, a significant limitation
- The age of transition – when the motor ‘learned to think’
- Technological breakthrough – what makes the brushless motor so much better?
- A Historical Overview – From Model Aviation to the DIY Workshop
- The Impact of Progress on DIY Culture
- The First Step in Evolution
