What's the deal with non brushless new tools ?

[sprior]

Was just pointed to this thread.  Are brushes readily available for the Festool dust collectors?  If so are they relatively accessible and easy to replace? They seem like the tools that are run for the most extended times and therefore the most like to actually wear out the brushes.

 

[aloysius]

The motor usually has to come out, or at least be exposed, to replace brushes &/or carriers.  There's a couple of (maybe even 3) German manufacturers of vac motors that supply the entire German & Danish markets at least, meaning that you can get a "original" OEM type motor as a replacement for just about any well-known brand, variant, wattage your heart desires.  Many users will replace the whole motor assembly rather than just the brushes as there's little extra expense involved.  My Nilfisk/Alto/Wap/Festo vac had a motor replacement about 20 years ago.  My Kraenzle/Festo vac has just recently required new brushes.  Both were simple DIY jobs.

Kemo also make high quality, auto start/delay circuits capable of running high currents.  These cost about Euro 15 or so. This German firm has long been making OEM & aftermarket circuitry to industry.  I've also used one of these to turn a standard WAP Turbo XL vac into a Festo SR5E auto vac.

All this means that, once purchased, one will NEVER have to replace a good quality, well-built vacuum or dust extractor.  Ever, barring actual physical damage to the superstructure.  It helps that virtually all Euro tool manufacturers don't actually make Vacs &/or dust extractors themselves, relying instead on a mere handful of specialist manufacturers of machines & components.

 

[sprior]

Wow, last weekend I replaced the brushes in the Dewalt router I use in my CNC, was 4 screws to remove the top cover the then the 2 brushes were right underneath and held in place with clips.  Total price for a pair of brushes about $12.  The idea that replacing the entire motor isn't that much more expensive than replacing the brushes seems pretty crazy by comparison.

 

[Svar]

Many users will replace the whole motor assembly rather than just the brushes as there's little extra expense involved. 

I don't get it. All brushes I ever replaced on power tools were 2 min $5 jobs. Replacing motor assembly will run into $100's and a serious PITA. What am I missing?

 

[jpmeunier]

Many users will replace the whole motor assembly rather than just the brushes as there's little extra expense involved. 

I don't get it. All brushes I ever replaced on power tools were 2 min $5 jobs. Replacing motor assembly will run into $100's and a serious PITA. What am I missing?

Power to weight ratio, battery life, maintenance free.

 

[AlexThePalex]

I don't know about the bigger Festool vacs, but on my Mini the brushes are easily replaced BUT you have to take the entire housing of the vac apart. It's a simple screw/unscrew job, but it takes time. Given how Festool repair service can easily charge you €70 per hour, one can understand where the extra cost comes from.

 

[Cheese]

Well if the discussion is about the ease of changing brushes in a brushed tool, Milwaukee takes the cake. For years the brushes were easily accessed from the outside of the tool. The brush access was denoted by a large, black plug that had a flat blade screwdriver slot. Everything was done from the outside. No internal meddling.

 

[CirclDigital]

Marketing sure is a powerfull thing..... for some battery powered tools the advantages can be worth the price difference. For the rest not so much.

Most corded tools are plenty powerfull and maintanance is hardly an issue, brusless or not.

 

[grobkuschelig]

On some of the cordless tools the brushless design has allowed for flexible voltage motors.

My example being the Fein SuperCut (brushless), which takes 12, 14 & 18V Batteries, where the brushed models (Multimaster, Multitalent) are limited to their respective battery platform (either 18 or 12v).

Might be a unicorn, but in this case, I love the added flexibility to enable me to choose between light and powerful.

 

[James Biddle]

If economics are the reason that Festool chooses not to use brushless motors in their cordless tools, how do you explain other companies like Makita and Milwaukee using brushless in a much wider variety of tools and selling them for less than Festool? 

 

[acknowlli]

I know I am waking up the dead here, but I just can't let it unanswered I read the entire thread and ended up astounded  why the simple and straightforward answer just didn't come up

The reason corded tools don't have brushless DC motors, is because those can't run on AC from the grid. They need low voltage at a very high current. This is exactly what batteries provide, but the opposite of what the power cord has to offer.

If you had brushless DC motors in a corded tool, you would need to convert low current, high voltage AC power to high current low voltage DC. That means you have to implement an additional power supply, that is bigger and heavier than the BL-DC motor itself.
Brushless motors just don't make sense i a tool running on AC. It would only make the tool bulkier and heavier, with no added benefits.

Mirka has corded sanders with brushless DC motors, to provide a super compact sander with a very low center of gravity. It runs on 48V and comes with a heavy external power supply, that is bigger than the sander itself.
(I know, they are slowly sorting that out, too. But so far the universal motor has the better weight-power ratio when it comes to AC.)

 

[dallas8338]

[member=68798]acknowlli[/member] - The ETS EC is a corded brushless motor and so is the Planex Easy.

Quote from the Festool USA website:
The new ETS EC 150 EQ is perfectly built for manual operation to reduce fatigue when carrying out overhead sanding work and a good feeling on edges, as well as convenient operation in any position. This sander is only 4 1/2" (116 mm) high, contains a brushless EC-TEC motor, and ergonomic housing geometry with perfectly balanced center of gravity. This sander also comes with additional innovative details such as automatic dust control, integrated sanding pad brake, and the unique Vibration Control System for added health benefits.

 

[Pant]

The mirka brushless sander plugs directly into the wall.

 

[acknowlli]

Agreed, the Planex has the power supply/motor combination because here it makes sense for improved weight distribution (away from the head). EC makes sense here because of the dustproof design.

Regarding Mirka, yes, as I said they are slowly figuring it out. The brushless sanders had external power supplies for many years. They start getting rid of those now.

Another benefit of BL DC is high torque at low speeds. That makes sense in sanders, because the addet weight from the power supply gets compensated, because you don't need a mechanical gearbox any more.

 

[AlexThePalex]

The brushless sanders had external power supplies for many years. They start getting rid of those now.

Those Mirka sanders did not have that external power supply to make the sander brushless. They had that external power supply so the sander could run a on a low voltage and make it suitable for wet sanding.

 

[DeformedTree]

Brushless has nothing to do with hi/lo current. hi/lo voltage. 

Brushless requires a controller, that is the difference.  It's an added cost, an if there isn't a need for it, they are not going to do it.

You design a motor for the need, if you need high torque, it will have high current draws.  Battery tools keep going to higher voltages so they can have more power without more amps.  Corded tools have never had much option, the voltage is either 120 or 230/240VAC.

 

[acknowlli]

Ok, that sounds interesting. Mirka has replaced the entire Ceros series (external supply) with the newer Deros (internal power supply). Does that mean Mirka doesn't offer electric sanders suitable for wet sanding anymore?

Just curious

 

[Bohdan]

There is a fundamental difference in performance between brushed and brushless motors. The brushless motor is an induction motor so if it is overloaded, by being pushed too hard, it will drop out of sync and stall.

On the other hand a brushed motor will simply draw more current and keep going, for a short time untill it overheats and burns out.

This means that, for the same user performance, a brushless motor needs to be nearly twice the wattage rating.

This doesn't mean that a BL motor will use more power. Both motors will use roughly the same power for the same job but the B motor can easily exceed its rating if required. In battery tools a BL is more efficient, and has more torque at low speed, so the battery lasts longer.

Comparing the wattage rating between B and BL motors will not give you any indication of how they will perform in a power tool in actual use.

To prevent burnout on brushed motors manufacturers fit temp sensors which, like on the TS55, shut them down until they cool down.

 

[Rick Christopherson]

There is a fundamental difference in performance between brushed and brushless motors. The brushless motor is an induction motor so if it is overloaded, by being pushed too hard, it will drop out of sync and stall.

As I already pointed out 2 years ago, brushless motors (specifically BLDC) are NOT induction motors, and these conclusions are therefore not correct.

 

[AlexThePalex]

Brushless requires a controller, that is the difference.  It's an added cost, an if there isn't a need for it, they are not going to do it.

There is a need for it because people want it. People want quiter motors that are more controllable and run smoother. Added cost? Hmm, not sure about that. Pretty sure that controller will soon be on a single chip costing 50 cents. Of course it costs a bit more now it is still new.

I remember how I bought my first hard disk drive back in 1997. Quantum Fireball 6,4 GB, top of the line back then. Paid €200 for it. Now you can buy a 2TB SSD for only €134. It has 300 times the capacity, 1/100th the size, and works about 80-100 times faster.

  Corded tools have never had much option, the voltage is either 120 or 230/240VAC.

Not much option? My smallest 220 volt tool draws 80 watts, my biggest 2600. Try that with your 36v batteries.