Are brushless motors more durable?

[Hawkinator]

I have read that a brushless motor is more efficient than a normal one, but is it as durable?  I can replace the brushes on my gear and keep going.  What wears out on a brushless?  Also, are the Festool motors slotless?

 

[ccmviking]

I have read that a brushless motor is more efficient than a normal one, but is it as durable?  I can replace the brushes on my gear and keep going.  What wears out on a brushless?  Also, are the Festool motors slotless?

Yes!  Obviously you don't have the brushes wearing on the Comutator.  This can cause a failure here if the brushes are ran to failure then you're pretty much replacing the whole motor and not just the brushes.  It will eventually most likely fail at some time anyway.  By not having the brushes to worry about you get rid of the #1 cause of failure in a DC electric motor.

Chris...

 

[ScotF]

And they are more efficient, thereby increasing power and battery life in cordless tools.

Scot

 

[woodnerd]

From my review of the T15 ...

"Most cordless drills use a brushed motor, which is simpler and less expensive to build. Brushless motors are far more complex and require an electronic control system. However, brushless motors can operate at higher speeds because there's no mechanical limitation imposed by the brushes and another part called a commutator required in brushed motors. Also, a brushless motor has a almost-flat torque curve whereas brushed motors lose quite a bit of torque at higher speeds. To put it in a nutshell, for a given size, brushless motors are faster, more powerful, generate less heat, and last longer while using less power."

 

[Alan m]

[welcome] to the fog

brushless sounds perfect.
why arent all tools brushless

 

[Administrator_JSVN]

Welcome to the forum and thanks for the question.

Festool tests it's brushless motors up to 1,000,000 screws. So, yes, they will last.

The plastic housing my disintegrate hundreds of years from now before the motor fails.  [tongue]

I'm not familiar with slotless technology and had to look it up. I'm pretty sure our motors are not slotless. It looks like slotless is used for very high RPM, i.e. 100,000RPM. Maybe someone like Rick Christopherson may know more about slotless technology and can shed some light on the topic.

Shane Holland
Festool USA

 

[RONWEN]

Welcome to the forum and thanks for the question.

Festool tests it's brushless motors up to 1,000,000 screws. So, yes, they will last.

The plastic housing may disintegrate hundreds of years from now before the motor fails.  [tongue]

I'm not familiar with slotless technology and had to look it up. I'm pretty sure our motors are not slotless. It looks like slotless is used for very high RPM, i.e. 100,000RPM. Maybe someone like Rick Christopherson may know more about slotless technology and can shed some light on the topic.

Shane Holland
Festool USA

Was that determined through testing???  [big grin]

 

[Deansocial]

From my review of the T15 ...

"Most cordless drills use a brushed motor, which is simpler and less expensive to build. Brushless motors are far more complex and require an electronic control system. However, brushless motors can operate at higher speeds because there's no mechanical limitation imposed by the brushes and another part called a commutator required in brushed motors. Also, a brushless motor has a almost-flat torque curve whereas brushed motors lose quite a bit of torque at higher speeds. To put it in a nutshell, for a given size, brushless motors are faster, more powerful, generate less heat, and last longer while using less power."

so why are festools slower?

 

[Deansocial]

Welcome to the forum and thanks for the question.

Festool tests it's brushless motors up to 1,000,000 screws. So, yes, they will last.

The plastic housing my disintegrate hundreds of years from now before the motor fails.  [tongue]

I'm not familiar with slotless technology and had to look it up. I'm pretty sure our motors are not slotless. It looks like slotless is used for very high RPM, i.e. 100,000RPM. Maybe someone like Rick Christopherson may know more about slotless technology and can shed some light on the topic.

Shane Holland
Festool USA

Maybe they should send some my way for testing, Screws dont really test a drill IMHO but drilling does so maybe they should drill 1000000 holes with it hitting the odd foreign object. My t18 broke when i hit a hidden nail with a 32mm spade bit

 

[tbellemare]

How did it break, Dean?

Tom

 

[Deansocial]

How did it break, Dean?

Tom

well it stopped working all together. It just beeped twice each time, Came back with a new motor

 

[AlexThePalex]

Wow, if it breaks so easily, I wouldn't call that durable.

 

[Rick Christopherson]

I'm not familiar with slotless technology and had to look it up. I'm pretty sure our motors are not slotless. It looks like slotless is used for very high RPM, i.e. 100,000RPM. Maybe someone like Rick Christopherson may know more about slotless technology and can shed some light on the topic.

As it applies to drill motors, slotless motor technology does not offer any appreciable benefit over the standard stator design. Slotless design would offer the greatest benefit in applications where ultra-smooth rotational positioning is required, such as the drive motors of a CNC axis.

EC-TEC drills utilize a planetary gear set with a very large reduction ratio. (I can't remember the ratio off the top of my head, but I believe it is at least 10:1.)  This means that the 24 steps within the rotation of the motor translates to 240 steps at the drill chuck (slightly more than 1 degree per step). Even at the very low speed of 250 rpm, that still translates to 60,000 steps-per-minute (1000 steps-per-second)--which is trivial.

................ To put it in a nutshell, for a given size, brushless motors are faster, more powerful, generate less heat, and last longer while using less power."

so why are festools slower?

In regard to drill motor applications, neither technology is operating anywhere near its "speed limit". However, what separates "Brushed" from "Brushless" is that you cannot directly control the speed of the Brushed motor externally under varying load.

The brushes in the motor perform the task that is called "Commutation". In simple words, this means switching the polarity of the motor windings based on the position of the rotating Rotor so they are always opposing the magnetic field in the stator.

Because this switching function is internal to the motor, the only thing stopping the motor from going into a "runaway" condition (ever-increasing rpm) is the mechanical load put on the motor. Conversely, the only way to control the speed of the motor is to change the voltage to the motor to overcome the mechanical load.

On a brushless motor, the commutation function is external to the motor and is controlled electronically. The EC-TEC controller sends a specific Frequency of pulses to the motor, and this controls the speed of the motor. The higher the frequency, the faster it turns. Sensors inside the motor tell the Controller exactly where the Rotor is with respect to the Stator, and from this, the Controller knows if the motor has "slipped" from its intended speed.

This is why an EC-TEC drill will increase its output power for a given RPM as the load on the motor increases.

Back to Dean's original question, the speed of the motor is the speed that the controller is telling it to go. It could go faster, but this is a drill, not a router.

 

[Deansocial]

i know it is a drill but it is a tad slow compare to others by a few hundred rpm, I tend to drill holes in steel now and again and could do with the extra speed

 

[AlexThePalex]

i know it is a drill but it is a tad slow compare to others by a few hundred rpm, I tend to drill holes in steel now and again and could do with the extra speed

Agreed. I love the speed on the Protool drills, 3800 rpm vs my T15's 1500.

 

[Deansocial]

wish they were availble when i bought my t15 but they weren't

 

[Rick Christopherson]

My t18 broke when i hit a hidden nail with a 32mm spade bit

When a spade bit, especially a 32 mm (1.25") bit, hits an obstruction, it comes to a dead stop almost instantly. However, all of the mechanical components of the drivetrain upstream from the bit are spinning at a much higher speed and have a much higher inertia (plus motor driven power). The resulting impact is so great that it will frequently rip the teeth off the most robust of gears. It's a similar impact that a SawStop tablesaw undergoes when its safety system engages. It won't necessarily destroy a drivetrain every time it happens, but the odds are very high, regardless of the brand in question.

 

[Rick Christopherson]

i know it is a drill but it is a tad slow compare to others by a few hundred rpm, I tend to drill holes in steel now and again and could do with the extra speed

When drilling steel, speed is not the friend of your drill bit.  [scared] It may drill a lot easier, but the heat is destroying your drill bit.

 

[Deansocial]

every diameter bit has its optimum speed for drilling in each material rick, I would have thought you would know that. I'm drilling 3mm holes so im guessing about 2500rpm in mild steel from memory. I also use cutting compound to reduce the heat build up

 

[Ken Nagrod]

i know it is a drill but it is a tad slow compare to others by a few hundred rpm, I tend to drill holes in steel now and again and could do with the extra speed

When drilling steel, speed is not the friend of your drill bit.  [scared] It may drill a lot easier, but the heat is destroying your drill bit.

Agreed.

My t18 broke when i hit a hidden nail with a 32mm spade bit

When a spade bit, especially a 32 mm (1.25") bit, hits an obstruction, it comes to a dead stop almost instantly. However, all of the mechanical components of the drivetrain upstream from the bit are spinning at a much higher speed and have a much higher inertia (plus motor driven power). The resulting impact is so great that it will frequently rip the teeth off the most robust of gears. It's a similar impact that a SawStop tablesaw undergoes when its safety system engages. It won't necessarily destroy a drivetrain every time it happens, but the odds are very high, regardless of the brand in question.

So it sounds like the drills don't have a protective clutch in them.  Kind of surprising considering their cost.  I'm not totally sure of this, but I vaguely recall that my big Milwaukee 18v has a clutch for just such a possiblity.  My Makita rotary hammers definitely have it.