What's the deal with non brushless new tools ?

[ach_78]

Hi all,

As we all know the advantages of brushless over brushed motors, I am pretty surprised that not all new Festools are going "EC" and still support brushed motors.

Brand new Kapex ks 60 is not brushless
Latest DTS sanders are not brushless
Recent HK saws are not brushless
and the list goes on...

Actually if you look at the FESTOOL line-up, EC is pretty much limited to cordless tools, with some exceptions. Not saying brushed motors don't work, but since brushless is better, why are we no getting the best choice even on corded tools.

I wonder what the motivation is beside manufacturing costs ?

IMO even corded tools would benefit from EC : more efficient means less heat. Nearly no wear. No maintenance. Last forever. More compact and lighter at equal torque/power. Smoother. Less sound pressure. I can't think of one single drawback of brushless compared to brushed (besides cost).

Now that brushless is becoming seriously mainstream, I find it increasingly difficult to justify (and accept) not getting a brushless motor on the latest brand new top of the line green tools.

Your thoughts ?

 

[TylerC]

Good question and thanks for raising the subject.  True, brushless motors come with many great advantages such as reduced power consumption, increased longevity, more compact design, and so much more.  However, they are still more expensive, by far, to produce.  Perhaps this will change in the futureAll things being equal, if brushless and brushed motors cost the same to build and implement, then yes, it seems like a good idea.  However, the economics don’t make that feasible at the moment.  For cordless tools with batteries it makes the most sense right now.  Batteries, by their nature, are limited in capacity for producing usable energy.  A corded product does not have that limitation.

Plus, we must also consider the function of the tool, how it is used, and if having a brushless motor brings a true benefit for the customer.  For example, for a tool like the CT Dust Extractor we offer in some countries an EC brushless version for special applications that require it.  This version is nearly 2.5 times more expensive compared to similar capacity units.  In this instance, these dust extractors meet different needs and have different designs, but this is just one example of the cost differentials when implementing such technologies.  Further, our current CT motors provide years of reliable service, are quite robust, and meet the needs of the extractors without additional costs.

The future will be sure to bring us many product improvements like efficiency, longevity, and performance increases across the board.  Yet even now we can enjoy many tools with the benefits of brushless technology.

Currently the tools available in North America that are equipped with brushless motors are:

C18 Cordless Drill
T18 Cordless Drill
PDC Cordless Hammer Drill
BHC Cordless Rotary Hammer
DWC Cordless Screw Gun
PSBC Carvex Jigsaw (cordless)
PSC Carvex Jigsaw (cordless)
PS Carvex Jigsaw (corded)
PSB Carvex Jigsaw (corded)
TSC Track Saw (cordless)
HKC Carpentry Saw(cordless)
ETS EC Sanders (3 models)

On a side note, Festool was one of the pioneers in bringing brushless motor technology to broader market application for portable power tools starting with the original C 12 in 2005.

 

[RustE]

I had a coversation with a co-worker whom is better versed in electric motors than I am.  It's lengthy because he likes to talk and also interesting.

Universal motors will operate on alternating current (AC) or direct current (DC) power sources.  These motors use brushes and a commutator to switch the polarity of the magnetic fields in the armature as needed to attract or repel the stator windings in order to develop torque.  Since the switching occurs mechanically and depends upon the orientation of the armature, the frequency of the AC current powering the motor does not limit the speeds at which it can operate.  Therefore, output shaft speeds higher than 3600 RPM are possible.

Brushless motors, or induction motors, operating on alternating current (AC) power sources are semi-synchronous.  This means that the motor operates at multiples or integer fractions of speeds that are synchronous with the frequency of the AC current powering the motor.  For 60-hertz AC power sources, the brushless motors operate at 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole), and 900 RPM (8-pole).

The Tesla induction motor, sometimes called a "squirrel cage" motor, uses the magnetic fields created in the stator windings to induce currents in the armature rotor, or squirrel cage, to develop running torque.  This inductive coupling eliminates the need for brushes and a commutator, making induction motors very simple and reliable.  Induction motors can often be found on air handlers for home furnaces, swimming pool pumps, and air compressors.  The big disadvantage to an induction motor is the very limited speed range at which it can operate as determined by the number of magnetic poles in the stator windings of the motor.

Induction motors run with "slip", meaning that they can never run in complete synchronization with the alternating current (AC) power source.  For a 4-pole motor, the synchronous speed is 1800 RPM when using a 60-hertz AC power source.  The slight "slip", or difference in speed from synchronous, allows induction to force currents in the armature.  These currents then create their own magnetic fields that counter those of the stator, creating the driving torque.  The bigger the slip, the more torque developed.  Eventually, if the slip is too great, then the effect fails and the motor stalls.

Most 4-pole induction motors that operate on a 60-hertz alternating current (AC) power source are rated at 1725 RPM.  The 75 RPM speed difference from the synchronous speed of 1800 RPM creates the maximum amount of driving torque, and since the speed is almost constant, this is also at the point where the greatest horsepower is developed.

 

[Kev]

I was actually astonished that Festool are releasing new products with brushed motors. Reducing cost has never seemed to be part of the Festool mantra and if you're designing a new tool why wouldn't you go brushless?

 

[kevinculle]

Ummm...they're already priced at the top of range and the added cost might reduce sales?

 

[charley1968]

Thanks for the explanation [member=63201]RustE[/member]

 

[demographic]

I'll start this off by saying that I have never used a Festol cordless drill driver yet but one thing I've noticed with the other brushless drill drivers (Panasonic mostly) is that they have a split second worth of delay between pulling the trigger and something happening.
Any brushed drill driver I've used (too many manufacturers to remember) have started turning pretty much immediately.

I've never liked the delay and wouldn't mind knowing if Festools offerings do the same?  In which case I'll likely never buy one.

Anyone?  I've never been a fan of the torque settings for putting screws into wood and prefer to let off the trigger as the screw is seated and somethimes just give its a little "blip" to get it that last half turn or whatever.
That last "Blip" is difficult to do accurately when the drill driver has to think about what its going to do for a half second before it does it.

 

[Job and Knock]

Using brushless tools with a bit of "lag" is like using a car with a turbo charger - you really do get used to it and pre-empt it so it doesn't slow down your work. At least that's what I find with my brushless tools (and with the Saab Turbos I had back in the 80s)

 

[Holmz]

I was actually astonished that Festool are releasing new products with brushed motors. Reducing cost has never seemed to be part of the Festool mantra and if you're designing a new tool why wouldn't you go brushless?

The message may have been less profit... basically it is brushless cost but stiff brushed.

Using brushless tools with a bit of "lag" is like using a car with a turbo charger - you really do get used to it and pre-empt it so it doesn't slow down your work. At least that's what I find with my brushless tools (and with the Saab Turbos I had back in the 80s)

Easier with the 122HP non turbo, as one rarely needed to let off the noise. I suppose they needed a thumb lock for the big toe.

 

[Rick Christopherson]

Brushless motors, or induction motors, operating on alternating current (AC) power sources are semi-synchronous.  This means that the motor operates at multiples or integer fractions of speeds that are synchronous with the frequency of the AC current powering the motor.  For 60-hertz AC power sources, the brushless motors operate at 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole), and 900 RPM (8-pole).

Even though what is stated here about AC induction motors is correct, it is not applicable to BrushLess DC (BLDC) motors, and may cause some confusion. First off, the name. BLDC motors are not induction motors. The description above is correct for induction motors, but BLDC motors are permanent magnet 3-phase motors, and are neither induction, nor have a slip-speed. The rotor contains permanent magnets, and does not rely on induced magnetic fields in the rotor.

The speed of a BLDC motor is driven by a frequency, but that frequency is not the line-AC frequency. It is an artificially created frequency in the motor controller. There are no limits, per se, for this frequency, except for any mechanical limits on what the motor can spin.

.....one thing I've noticed with the other brushless drill drivers (Panasonic mostly) is that they have a split second worth of delay between pulling the trigger and something happening.

This delay is not a function of the motor or motor type, but of the soft-start nature of the PWM controller, as it is slowly ramping up power to get the motor to spin. As a matter of fact, it is typically more pronounced on non-BLDC motors because they lack the direct feedback at the winding-level. They can only see the external shaft RPM, which is less reliable at near-zero speed. The BLDC motor has internal sensors that tell the controller the exact rotational position of the rotor. (See below)

=============================================
Back to the original topic. BLDC motors are much more complex than brushed motors, and their respective controllers are more complex. The brushed motor PWM controller needs just a single power transistor for the output, and a single RPM sensor for feedback. The controller only needs to compare the set-speed with the feedback speed, which is a very simple circuit.

The BLDC motor, on the other hand, must include the added expense of the permanent magnets, plus at least 2 internal hall effect sensors to tell the controller the exact rotational position of the rotor.

The controller, instead of just 1 power transistor, it must have 6 power transistors. It doesn't just turn power on/off to the motor, but needs to artificially create a 3-phase, square wave, AC power to the motor from a DC supply. 3 transistors are required to control the 3 phases for positive voltage, and 3 more transistors to control the negative voltages.

The purpose of the brushes in a universal motor are for mechanical commutation (polarity reversal) for the windings. With a BLDC motor, this must be accomplished externally by the controller. This requires that the controller know the exact rotational position of the rotor (kind of like what the positions are on the hands of a clock). The controller uses the two sensors inside the motor to calculate the exact position, and it then uses this result to determine which of the 6 transistors must be turned on for that instant in time. And that isn't even to control the speed yet. That's just what's necessary to make the motor turn at any speed.

The speed control is a separate, but related circuit, which controls how often all this other switching is taking place based on the amount of power going into the transistors. Therefore, the controller for a BLDC motor is much more complex than a simple speed controller for a universal motor.

 

[ach_78]

I know for a fact that a T18-3 driver is as instantaneous as it get, yet it is brushless.
So brushless does not mean lag.

 

[RustE]

[member=191]Rick Christopherson[/member] Thanks for the BLDC motor information.  My coworker and I did not discuss DC motors, as we were talking about the HK 55 EQ having an universal AC motor.  The AC induction motor is in my Makita MAC700 air compressor.

 

[AlexThePalex]

I'll start this off by saying that I have never used a Festol cordless drill driver yet but one thing I've noticed with the other brushless drill drivers (Panasonic mostly) is that they have a split second worth of delay between pulling the trigger and something happening.
Any brushed drill driver I've used (too many manufacturers to remember) have started turning pretty much immediately.

I've never liked the delay and wouldn't mind knowing if Festools offerings do the same?  In which case I'll likely never buy one.

There is no delay whatsoever, in fact, I've never used a drill that I can control so precisely as my T15.

 

[grbmds]

I'm always curious as to the real advantages of a brushless motor for people like myself who regularly use the tools but not as part of my everyday work. It has never seemed like it really makes any difference in the actual results or, for that matter, on the life of the tool. For example, I don't remember ever replacing a sander or drill because the motor wore out. I have replaced brushes on more than one sander and on other tools but that isn't a big deal nor does it cost very much. I realize that this isn't the topic of this thread so sorry about that. I also understand that for those of you who use tools as professional builders, contractors, cabinetmakers, etc. the life of the tool may be affected. However for many of us, who make furniture, cabinets, and miscellaneous things out of wood, I have never felt that a brushless motor is worth any additional cost (if there is additional cost).

 

[aloysius]

Why would any company want to produce long-lasting, maintenance free tools?  It flies in the face of the commercial realities of contemporary economics.  Festo is I'm sure bound by similar commercial imperatives as any other small-medium enterprise, having a board that reviews & oversees company operations and shareholders who demand continuing, if not increasing dividend yield and market capitalisation.

 

[Stephen B]

[size=13pt]Last time I looked, Festo/Festool was a private family company.
[size=8pt]https://www.festo.com/group/en/cms/11008.htm

Why would any company want to produce long-lasting, maintenance free tools?  It flies in the face of the commercial realities of contemporary economics.  Festo is I'm sure bound by similar commercial imperatives as any other small-medium enterprise, having a board that reviews & oversees company operations and shareholders who demand continuing, if not increasing dividend yield and market capitalisation.

 

[Paul G]

Why would any company want to produce long-lasting, maintenance free tools? 

Because there's folks willing to pay a premium for it. The let down is when the high priced tool is also high maintenance.

 

[aloysius]

Even PLCs have boards of directors & shareholders.  It's a standard corporate model.  Unless of course it has sole proprietorship, which it doesn't.

Planned obsolescence is a basic, well documented and all but universally adopted tenet of capitalist entities.

 

[ach_78]

Thanks for all the input, not surprised but I actually kinda hoped there was more than just pure mfg cost in play.

Agreed, the focus has been very much on cordless tools lately, and brushless motors are one big technical bullet point in that regard. But new corded tools are released too...

As for the actual real-life advantage of BL, good question.

In most case let's face the fact that it will not show in the work result. I really doubt one could tell a BL or brushed tool has been used from the smoothness of the cut, sanding, etc.

But it will make a difference in terms of confort in use : for an equally powerfull tool the BL should come in a more compact, lighter, smoother running form. It will generate less heat (my Rotex 150 can get quite hot after prolonged use). It should make less noise too.

Maintenance is another issue but I will admit most owners will never have to replace the tool because the motor is worn out. Heavy users, those who sand all day long for example, will disagree.

Bottom line (just my opinion) : BL is better, it is the "best" choice for electric power tools. I understand it cost more to make but looking at Festool price tag, I expect it to be there, included. Just doesn't feel right buying a brushed-motor Kapex in 2017 just to name an example. I'm eyeballing a Kapex and a DTS sander but the motor type is kinda giving a sour taste to the deal (it's a big chunk of hard earned money).

 

[Job and Knock]

Bottom line (just my opinion) : BL is better, it is the "best" choice for electric power tools. I understand it cost more to make but looking at Festool price tag, I expect it to be there, included. Just doesn't feel right buying a brushed-motor Kapex in 2017 just to name an example. I'm eyeballing a Kapex and a DTS sander but the motor type is kinda giving a sour taste to the deal (it's a big chunk of hard earned money).

Here's maybe something for you to think about, then. I had much of my kit stolen (I am a site carpenter and shop fitter - something between a framer and trim carpenter with a good dose of interior fitout thrown in for good measure) about 2 years ago and found myself facing the uphill struggle of replacing something like 60% (by value) of my fairly extensive tool kit. Very, very few corded tools by any manufacturer are offered in brushless form. In fact one of the few tools I can think of from the top of my head is the Mirka Deros sander. Why is this? The plain fact is that brushless tools cost more (if you don't believe me - check the differences in price point between brushed and brushless combi drills, circular saws and SDS drills for any of  the major cordless tool brands) and the saving in weight on corded tools is far less attractive than having a tool at 2/3 the price. Any contractor will tell you the same - and it's those guys who buy the tools in volume and who will need to be convinced of the advantages. For cordless that argument is pretty easy to make; brushless = less weight (on what is probably already a heavy tool) plus 40% longer run time and an increase in power (my Makita DHS680 saw is rated at over 600 watts vs. the DSS610 corded version at 350 watts) but where are  the same compelling arguments for most corded tools? I think you may be a very long time waiting for brushless everything