A brushless mains motor will be an induction motor, running at 1400 or 2800 rpm, but a brushed mains motor in a power tool will run anywhere from 10,000 to 30,000 rpm, so it will be a lot noisier.
- Thread starter MattF
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Maker
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Me too, but I went from a ten year old Bosch green to top of the range DeWalt so it's not really a fair comparison.
Deltic
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just a small upgrade then.Me too, but I went from a ten year old Bosch green to top of the range DeWalt so it's not really a fair comparison.
Kayos
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Me too, but I went from a ten year old Bosch green to top of the range DeWalt so it's not really a fair comparison.
I went from old/abused 18v Makita, mix of brushed and brushless to shiny new 18v Makita, all brushless. The sds was noticeably better and so was the impact driver
MetalMonkey
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Brushless for cordless for definite. For one thing brushes are not usually replaceable on cordless tools so its usually a new motor when they die. More power, better battery life, not much difference in cost now. Clear win for me.
Corded tools it is less clear cut, variable speed is nicer on brushless, but otherwise I wouldn't be too bothered either way.
Corded tools it is less clear cut, variable speed is nicer on brushless, but otherwise I wouldn't be too bothered either way.
Whilst that's true on cordless stuff aimed at the diy market any cordless stuff rated for pro use that I've worked on has always had replaceable brushes.
Agroshield
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I would agree with that. I have had to fix four or five of the cheap breakers that TS and SF sell (e.g. https://www.screwfix.com/p/mac-allister-msbr1700-a-16-2kg-hex-shank-electric-breaker-230v/623HV). All of them have shaken the brushes to bits - you open them up and carbon fragments come out.
Agroshield
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Agree. And you can even buy brushes for all the home-gamer stuff (Silverline/storm. MacAllister, etc.) from the likes of Mr Carbon Brush (https://www.mrcarbonbrush.com/). Most of the China-sourced tools are the same inside - the casing might be a different shape or colour but the brushes are fairly universal.
Dr.Al
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If a motor is being advertised as brushless, it's very unlikely it's an induction motor. While it's true that induction motors don't have brushes, there's a different type of motor called a "brushless permanent magnet motor", so calling an induction motor that would be (arguably) false advertising. Brushless permanent magnet motors can be considered to be an inside-out brushed permanent magnet motor, with the function of the commutator being performed by the electronics driving the motor.
Some types of brushless permanent magnet motors are often referred to as "brushless DC motors", although the latter term means different things depending on who you talk to, so it's not a good name. The same is true of the term "brushless AC motor". In practical terms, there's very little difference between "brushless AC motors" and "brushless DC motors": they're both AC. Some people consider "brushless DC motor" to mean a brushless permanent magnet motor driven with trapezoidal currents whereas a "brushless AC motor" is one driven with sinusoidal currents; other people consider "brushless DC motor" to be the combination of a brushless permanent magnet motor (either trapezoidal or sinusoidal) and drive with a variable voltage DC input such that it "looks" like a brushed DC motor to the outside world. This caused me a lot of confusion when I was starting my PhD (which was in control of brushless permanent magnet motors).
Also, an induction motor can run at speeds other than "synchronous speed" if driven by a variable speed drive: these can go a lot faster if desired (including the speeds you quoted for brushed mains motors). Brushless permanent magnet motors have a much higher power density than induction motors though, so wouldn't be a good choice in a hand tool. Brushed motors will typically be noisier at any given speed than other motors due to the brushes rubbing on the commutator, although bearing quality and the presence or otherwise of a cooling fan will probably have more of an effect.
None of this is particularly relevant to the OP's question, I just thought some people might be interested.
Agroshield
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The observation that brushless DC motors of power tools are generally permanent magnet ones is very relevant.
Late last year, Mr Kram posted a picture of his brushless grinder that he he opened and cleaned. It was covered in fine steel swarf attracted to the motor's magnet.
Having brushless, but steel-dust-attracting, objects in a metalworking environment may be less beneficial than brushed ones.
Dr.Al
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A lot of brushed motors have magnets in too; they're just on the rotor (rotating part) rather than on the stator (stationary part). Some brushed motors use a wound field (especially mains ones which put the field in series or parallel with the armature such that they'll run on AC current), but the power density from permanent magnet brushed DC motors is higher so they're probably more common in cordless tools, especially those with reversing switches.
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slim_boy_fat
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MattF
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Brushed, or brushless?
MattF
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Morrisman
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I bought a chop saw 15 years or more ago, a brand new Ebay special, but it does the job. It came with a spare set of brushes, which didn’t bode well..... but I still have it, still use it, still have the original brushes in it.
It’s only hobby use, not 8 hours a day, but still pretty good going.
No idea where the spare brushes are though, as I’ve moved house 5 times, and moved countries twice, since ’I put them somewhere safe’.
Sorry autocorrect
Meant to be groundworkers still by brushed
eLuSiVeMiTe
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My old mitre saw lasted 20 years on its original brushes and did a huge amount of workI bought a chop saw 15 years or more ago, a brand new Ebay special, but it does the job. It came with a spare set of brushes, which didn’t bode well..... but I still have it, still use it, still have the original brushes in it.
It’s only hobby use, not 8 hours a day, but still pretty good going.
No idea where the spare brushes are though, as I’ve moved house 5 times, and moved countries twice, since ’I put them somewhere safe’.
Saw was replaced this year but 100 quids worth of parts and it's on good shape for a decade or so as backup saw
qwakers
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i can attest to brushed being tougher, dropped a makita 18v impact into a bucket of water once.
grabbed it out, shook the water out and carried on using it. no problems.
