# IPM motor questions: Why not an IPM outrunner...why doesn't this exist?



## remy_martian (Feb 4, 2019)

What electric car application has demand for an outrunner? 

The smarter engineers run an axle out from a chassis mounted inrunner to minimize unsprung weight.


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## rishimaze (May 23, 2021)

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## kennybobby (Aug 10, 2012)

Maybe because this is a forum for ICE conversions and diy electric cars using electric motors? Justa guess


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## remy_martian (Feb 4, 2019)

yup









Outrunners are typically used in aircraft & in hub motors.

Hub motors suck, which I addressed in my posting already.


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## brian_ (Feb 7, 2017)

rishimaze said:


> There are quite a lot of IPM inrunners, but I have never heard of an outrunner that is IPM. Why not? I admit that the motor bell would gain some weight in the process and maybe that's the main reason for not making IPM outrunners?


Outrunners (or outer-rotor motors) are typically used where the intent is to maximize the radius to the rotor-stator gap, realizing that the stator is much bulkier than a surface-magnet rotor; burying the magnets in a bulkier rotor would negate that advantage.

While the higher rotational inertia of the outrunner design is desirable (or at least tolerable) in some applications, making the rotor much more massive probably still isn't a good idea.



rishimaze said:


> This can't be worse than the spinning mass of a hub motor!


Direct-drive in-wheel motors are another mess entirely, but I'll note that a direct-drive motor runs at only wheel speed, while a normal geared motor runs at a significant multiple of that speed, making rotational inertia much more important.



rishimaze said:


> The mass of an IPM inrunner armature vs an SPM armature is probably pretty close to the same. There's no added spinning mass issues.


Sometimes it's about rotational inertia, not just mass, and rotational inertia is about the radius where the mass is located. If a IPM inrunner rotor and a SPM outrunner rotor have the same mass and the same radius (to the rotor-stator gap), the outrunner will have much higher rotational inertia because that mass is at a larger radius.



rishimaze said:


> Most IPM inrunners have the magnets angled inwards in a V like this. Not all do, but this is very common. Does anyone know why?


If they were not angled in, they would just be at the surface, and would be surface permanent magnets. If you look at the flux paths at various speeds - not just the mathematical models of motor performance - you would probably find that the interior magnets in a vee configuration are suited to producing reluctance torque at higher speed, which is what the "MTPA" discussion appears to be about. Be prepared to look at a lot of diagrams in a lot of articles...


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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

rishimaze said:


> Agreed hubs tend to suck. Good thing I never mentioned them other than as a bad example. LOL
> 
> The title of the web site is "electric cars", but there are plenty of people on here, myself included, not building cars or anything 4 wheeled. This web site is about EV's of any kind, not just cars despite the domain name.


OK. What are you building? What application is this for, to where an inrunner is suboptimal?

You agreed hub motors suck. You did not say you were building an airplane. What application did I miss? Nuclear submarine?

What's the end problem being solved, because you're creating many problems by playing with motor magnet configs like a 2 year old with a Lego set vs defining a specific problem being solved? Brian mentioned some of them.

Pancake motors solve a packaging problem. Period - they suck at just about everything else. This "lever" you speak of, presumably to produce higher torque, is crap, as it integrates magnetic forces over the radius and do not act on the rim of the motor.

The SPMs being held in that photo of yours are not "categorically IPM" - that configuration of SPM keeps the magnets from fragging/flying-off at high RPM and flat magnets are cheaper than arcs.

It's easy to fall in love, but love leads to doing dumb things.


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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

A pancake motor uses a flat armature to create a super thin mover, unlike the sloppy marketing use of the term in your toy R/C outrunner motors:



https://www.printedmotorworks.com/brushed-pancake-motors/



Go play with your pile of Lego blocks - nobody's stopping you from engaging in a pointless waste of time (are you a student or academic by any chance?). When you grow up, you'll learn the first step in finding a solution is to properly define (& constrain) the problem. At that point, amazing things can happen. Solutions looking for problems almost always fail.

What does the 2 year old come up with? 7 monkeys typing Shakespeare.


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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

When ya got nothing after you were making foolishly arrogant posts, telling an industry veteran that a pancake motor has peripheral magnets as an outrunner, use mirroring.


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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

No...you made unqualified assertions.

You were asked what application this was for. Still waiting for an answer. 

You were also set loose to go play, but you clearly don't have the confidence to go down the rabbit hole alone and are super-worried about wasting your own time on this boondoggle vs wasting everyone's in a group hug. Group fail is acceptable for Gen Z.

Go look into it. Even us jerks have open minds to new discoveries.


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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## kennybobby (Aug 10, 2012)

It seems that the slanted IPM magnets help focus and concentrate the flux of the poles; but being embedded they also increase the air gap distance which reduces the flux in the gap and the back emf voltage; and they rigidly and securly hold the magnets in the rotor for high speed rotation without concern for flinging magnets loose from glued-on surface mounting.

This is from the ford mach-e motor teardown video, there is a double row of internal magnets, so 4 magnets per pole










end view of the 8-pole flux pattern 










and on the rotor surface showing a step or skew in the laminations to reduce cogging torque











the flux appears concentrated to correspond over about 6 slots/teeth per pole with 48 slots in the laminations. 
Wound with some large gage flat profile wire with hairpin end turns











Maybe for an outrunner the magnets would be slanted in the opposite slope such that the magnetic field would diverge to match the wider pole teeth of the outrunner stator. How many poles in your outrunner?


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## rishimaze (May 23, 2021)

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## piotrsko (Dec 9, 2007)

Laminated steel is for normalizing losses, eddy flows and In some cases almost eliminating them. Also makes production easier and cheaper.

15krpm is ok when the motor weighs a couple ounces, but when it weighs a hundred pounds, operating forces start exceeding material strengths so you end up chasing weight increases or buying and attempting to machine exotic high strength materials which is possible but expensive. In tesla's case, their motor took a long while to get where they are today.


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## rishimaze (May 23, 2021)

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## brian_ (Feb 7, 2017)

rishimaze said:


> ...
> This is IPM and no angled magnets. Outer magnet faces are alternating north and south poles. This style of IPM inrunner is fairly common. It's essentially an SPM, but the magnets are buried so it is categorically IPM.


That's a really crude magnetic design - it looks like someone did just enough work to mount the magnets, and put no thought into magnetic flux path at all. Well-designed IPM rotors (e.g. the ones in every production EV with a PM motor) don't look like that, and my guess is that you won't get much reluctance torque from that rotor.


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## kennybobby (Aug 10, 2012)

What could possibly be the added benefit to IPM an outrunner, versus the added weight and inertia? Seems like the added mass would especially negate any in a flight application.


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## brian_ (Feb 7, 2017)

I think it would make sense to understand what a "pancake" motor really is. The term is used to describe the _shape_, with axial length short compared to the diameter; it isn't an internal configuration. Generally pancake-proportioned motors are assume to be _axial-flux_ designs, in which either two stators sandwich a rotor (like disk brake caliper pads sandwiching a disk brake rotor), or two rotors sandwich a stator; however, some very pancake-proportioned motors are conventional _radial-flux_ designs, just with a large diameter and short length.

The Integrated Motor Assist unit of the old Honda Insight hybrid was a good and well-known example of a large-diameter and axially short (so "pancake" shaped) motor of conventional radial-flux inner-rotor (a.k.a. inrunner) configuration. By the way, this has a concentrated winding stator and surface-mounted permanent magnets, which are uncommon features in modern EV motors but more common in pancake-proportioned designs. I assume that the proportions were desired to package the motor between the engine and the transaxle (as required by the specific parallel hybrid configuration used), and the large gap radius and high pole count were suitable for the relatively low operating speed resulting from operating at engine speed.


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## brian_ (Feb 7, 2017)

rishimaze said:


> Help me understand please. The magnet poles seem to be where 2 sets of V's meet close to the surface of the armature, not in the middle of each V. IS that what you see too?
> ...
> Magnet angles...lol....first I'd have to understand why they are angled to begin with before I knew which way to angle them.


No, the static field created by the permanent magnets is the opposite of that: where the magnets are closest to the rotor surface is where the flux density changes most rapidly with location, which is visible with the green sheet.



rishimaze said:


> My assumption in the steps in the armature are that there are also 4 sets of magnets, each slightly shifted a couple of degrees from the other sets. This would effectively make segmented magnets and also reduce cogging. If you look close at the magnets in motors from Tesla, you'll see they use segmented magnets. There is some sort of current that flows across the faces of the magnets in the opposite direction of rotation. It effectively creates drag in the motor and losses. The many smaller magnets instead of single large ones somehow breaks up this current flow. I read about it once, but most of the math went soaring over my head! Im not a motor expert and even looking at complex math makes my brain smoke badly!


Yes, most PM motors (from Tesla and everyone else) have this slight stagger in segments, apparently to reduce cogging. Due to the construction details of the carbon-fibre-sleeved Plaid motors, they do not have this stagger.



rishimaze said:


> Iron on top of the magnets somehow helps with field weakening (more complicated math). MTPA also uses the iron somehow (more math lol!). Magnet pole shaping can't be done with SPM, just "soak up" the back pole of each magnet. IPM with angled magnets can do this. I think those 3 things are the big reasons for IPM.


Sort of kind of yes.
But yes, the way the iron affects the magnetic flux path is the reason for the magnet configuration, and the source of reluctance torque.



rishimaze said:


> Magnets not slinging off isn't that big of an issue. You can look at the KV's offered by Astroflight and see that 11,000 RPM on large SPM inrunners isn't unusual. RC sized inrunners have much higher RPMs and they are SPM as well. I don't think this is a compelling reason for IPM over SPM, but it would stop this from ever happening.


the iron does normally retain the magnets, but again due to some construction decisions the Plaid motor has the pole cap sections physically separate from the rest of the iron; the caps and magnets are retained by the carbon-fibre sleeve. Magnetically the sleeve is bad but the complete gaps in the iron path are good (as always, design is an exercise in compromise).



rishimaze said:


> I wonder if I machine a long triangle of cast iron that fits inside each V and between each V, if that is "good enough" to make this IPM? I don't think it needs to be laminate like the stator does. Looking at outrunners and hubs, the outer ring is never laminate. I think this is only needed in the stator to deal with the collapsing magnetic fields and related heating issues. Inrunner armatures are cut from laminate because otherwise the center of the stator lams is just wasted. So why not make the armature from the centers of the stator lams and use up the otherwise wasted material.


Ideally, solid iron is not used anywhere in the magnetic path of any electric motor, although I do realize that it is used as the back-iron for surface-mounted PMs. IPM inrunner rotors (not just the stator) are all laminated, and it is not to reduce wasted iron - a cast iron rotor could easily have axial holes through it just like the laminate stack.

The point of laminations is that they allow magnetic flux readily in the desired direction (the plane of the laminations), but resist perpendicular induced electrical eddy currents resulting from changing flux... and yes, even a PM rotor experiences changing flux due to the stator.

I think to get anywhere useful in this aspect of motor design you will need to understand what the q-axis and d-axis are, and the effect of magnetic saliency ratio... and to consider the magnetic flux path in detail.


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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

rishimaze said:


> Hey! There we go! Stuff that might tell me why IPM is good or bad in an outrunner or at least how to possibly do it best. Can you site a few white papers about this stuff please. I clearly have some reading to do and didnt even know what questions to ask beyond the general one of IPM and outrunners. Seems you have a better handle on the theories than I do!


A "white paper" is a document written by the marketing department of a company that wants to sell you their $hit. I've written them, as have engineers who worked for me.

Why you keep asking for papers from minions you're trying to recruit here for your boondoggle is beyond me. Nobody showing up here in this thread of yours is a traction motor designer and they have the same Google skills you should have (though Brian's Google-fu is God-tier).

You're in the wrong place, but for one reason...you want a problem stated by end users for your "solution"; a solution the braintrust of Masters and PhDs in Physics and Engineering planetwide for over a century has failed to "discover" because not a single problem has led to an IPM outrunner being an acceptable, optimal, solution. You put the cart before the horse and you're asking the cart why horses are so great.

And it's "cite", as in "citation".


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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

If you're going to hang out with intelligent people here, LEARN the terminology and methodology vs childishly lashing out with your arrogance and ad hominem attacks.

1. Learn to read and interpret scientific and engineering publications. Nobody will do that for you.

2. Nobody said there wasn't going to be math and physics in motor design. Accept that & do the math & physics or take your ball and bat and go home.

3. When an engineer tells you to go off and understand certain fundamental concepts, you go do it vs brush it off as unimportant and ask him to go do more work for you simply because he responded. He spent the time - it's your turn to put in at least 100x that he did....in the direction he sent you. He's your superior or wtf are you doing asking questions? You call it condescending, but I submit you simply don't know your place.

4. Define the problem FIRST. This forum of application-oriented people will not do that for you just because you keep repeating a solution out of your own confirmation bias. What is the problem being solved?


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## piotrsko (Dec 9, 2007)

Said it before and I see it needs saying again: Remy is usually correct although although intolerant of errata. Sometimes blunt is mandated to redirect attention or alter an incoherent thought trajectory.

If you are so convinced you have a technology shattering idea, go and TRY to build one. I have 10 lbs popcorn and make my own beer. I can wait.....do hurry it up a bit, however, my life expectency is only another 20 years.


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## rishimaze (May 23, 2021)

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## rishimaze (May 23, 2021)

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## remy_martian (Feb 4, 2019)

Again, follow the process. 

Define the problem you are trying to solve vs finding a problem for a solution NOBODY has solved a problem with in over a century of motor development and with hundreds of thousands of brains being applied.


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## piotrsko (Dec 9, 2007)

Then go find the appropriate motor engineers and ask the same questions. Be warned, they appreciate aquiring pictures of Ben Franklin or other obscure dead presidents in mass quantity. 

Excuse me, I have to chase people off my lawn.


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## rishimaze (May 23, 2021)

Neither of you are remotely helpful. Go abuse a large boulder instead of humans!

You have literally NOTHING useful to add! 
NO ONE wants your criticism, arrogance and giant egos! 

Make the world a MUCH BETTER place and DIE! 
Your absences on this world will improve things here significantly!


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## brian_ (Feb 7, 2017)

rishimaze said:


> Seems you are saying the magnet pole is in the bottom of the V and furthest away from the surface of the armature. Or maybe you are saying the entire chunk of laminations inside the V is the pole?


Yes, sort of. The pole appears that rotor surface radially outward from the vee between the magnets.



rishimaze said:


> I'm aware of using solid iron in stators being bad and why stators, transformers and other things like them with alternating magnetic fields use laminations. The back metal or outer ring of an outrunner needs to be a single solid piece of metal. I think anything else would potentially fly apart.


Not really. The rotor spins and needs to hold together, whether it is inside or outside of the stator.



rishimaze said:


> Why would you care to resist eddy currents with laminations in the armature? Isn't that the point of segmented magnets? Once I get past the discussion part of this and start actually building this crazy thing, I'll be considering details like this and probably using segmented magnets. I've read about those eddy current and why better designs of any kind of PM motor use magnet segments instead of single large magnets.


Segmented magnets are unrelated to eddy currents. Eddy current waste energy and heat whatever components in which they occur, so you always want to prevent them.

By the way, the Tesla Plaid motors use one-piece magnets the whole length of the rotor, so there are no segments and no offset between them.


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## electro wrks (Mar 5, 2012)

rishimaze said:


> Mr Industry Veteran is abusive, offensive, rude, arrogant, condescending, intolerant and overall a generally BAD human with psychopathic tendencies! I'm sure in his little world of narrow minded, ego worshiping sycophants he fits right in, but that is CLEARLY NOT THE CASE for everyone else. Too bad...I'm sure he's pretty smart...assuming you can get past the planet size personality issues! All he presents is negativity, bashing and road blocks and never actual helpful information. Pretty sure he gets banned from various forums all the time for his behavior!


In the "Terms of Use" for this forum it says "You may not":

"Use the Web Site to post or transmit any unlawful, harmful, threatening, abusive, libelous, flaming, hateful, offensive (whether in relation to sex, race, religion or otherwise), defamatory, obscene, vulgar, harassing, pornographic, profane or indecent information of any kind, including without limitation any transmissions constituting or encouraging conduct that would constitute a criminal offense, give rise to civil liability or otherwise violate any local, state, provincial, national or international law. "

It's a puzzle to me why some people that have been repeatedly violating these terms, haven't been kicked off. 

Moderators, can you do your job?

Meanwhile, I just use the Ignore feature under the Account Settings to weed out these bad seeds. It sure saves a lot of wasted time having to deal with bad people.


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## remy_martian (Feb 4, 2019)

rishimaze said:


> Neither of you are remotely helpful.


I have given you about 4 first-year engineering lectures' worth of guidance, several times. 

Brian gave you a 3rd year motor design course lecture contents' guidance on what you should go learn

You hear, but you don't listen.

Nobody here will guide you or advise you in motor design, despite several people here with enough background in experience and education to be able to design a motor.

The problem is, it takes several hundred hours to do so and spending those hours at McDonalds will get them 4 Leaf motors that are sufficient for most of the problems arising on this site. They also have better things to do with their time.

The following is the _only_ application for a ground vehicle that might be able to use an outrunner motor:


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## remy_martian (Feb 4, 2019)

electro wrks said:


> In the "Terms of Use" for this forum it says "You may not":
> 
> "Use the Web Site to post or transmit any unlawful, harmful, threatening, abusive, libelous, flaming, hateful, offensive (whether in relation to sex, race, religion or otherwise), defamatory, obscene, vulgar, harassing, pornographic, profane or indecent information of any kind, including without limitation any transmissions constituting or encouraging conduct that would constitute a criminal offense, give rise to civil liability or otherwise violate any local, state, provincial, national or international law. "
> 
> ...


@rishimaze is fine, just has no idea how to proceed so he's lashing out.

meh


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## rishimaze (May 23, 2021)

electro wrks said:


> In the "Terms of Use" for this forum it says "You may not":
> 
> "Use the Web Site to post or transmit any unlawful, harmful, threatening, abusive, libelous, flaming, hateful, offensive (whether in relation to sex, race, religion or otherwise), defamatory, obscene, vulgar, harassing, pornographic, profane or indecent information of any kind, including without limitation any transmissions constituting or encouraging conduct that would constitute a criminal offense, give rise to civil liability or otherwise violate any local, state, provincial, national or international law. "
> 
> ...


I agree! Please boot Mr Industry Veteran ASAP!!! His behavior is FAR FROM NEW!!!


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## rishimaze (May 23, 2021)

remy_martian said:


> I have given you about 4 first-year engineering lectures' worth of guidance, several times.
> 
> Brian gave you a 3rd year motor design course lecture contents' guidance on what you should go learn
> 
> ...


don't care...you are useless, condescending, arrogant, negative and abusive!
I will literally NEVER bow and worship before you!
GO AWAY!!!


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## rishimaze (May 23, 2021)

SO FOLKS!!! HOW ABOUT WE FOCUS ON WHAT THIS THREAD IS FOR!!!

YOU KNOW IPM OUTRUNNER DESIGN!!!
YOU KNOW USING MTPA WITH AN IPM OUTRUNNER!!!!

I'VE ABOUT HAD IT FRANKLY! MR INDUSTRY VETERAN HAS ABSOLUTELY RUINED THIS THREAD WITH HIS HIS NEGATIVITY, ARROGANCE, ABUSE AND CONDESCENDING BEHAVIOR. THIS IS LITERALLY THE LAST TIME I POST HERE IF THIS DOESN'T STOP NOW!!! SIMPLY PUT, HE IS A ROYAL PAIN IN THE ASS AND RUINS EVERYTHING WITH HIS LOUSY ROTTEN BEHAVIOR!!!

MODERATORS: GO LOOK FOR YOURSELVES AT HOW MANY PEOPLE HE HAS OFFENDED!!! I AM JUST HIS LATEST VICTIM!!! WHEN DO I ATTACK ANYONE WITHOUT THEM FIRST SLAMMING ME AGAINST THE WALL OVER AND OVER AGAIN?! NEVER!!! HE JUST DOES IT AND YOU LET HIM!!!

PUNISH REMI_MARTIN ASAP!!!


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## rishimaze (May 23, 2021)

LITERALLY ONE MORE EVENT FROM HIM AND I JUST SHUT DOWN MY ACCOUNT. PEOPLE LIKE HIM RUIN EVERYTHING FOR EVERYONE ELSE!!! I DON'T NEED PEOPLE LIKE HIM IN MY LIFE! IF THAT MEANS LEAVING THIS FORUM FOREVER...SO BE IT! THIS WOULD BE FAR FROM THE FIRST TIME IVE DONE THAT JUST TO GET AWAY FROM "PEOPLE" LIKE THIS!

*MODERATORS: PUNISH REMI_MARTIN FOR HIS MANY CRIMES AND OFFENSIVE EPISODES!!!*


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## MattsAwesomeStuff (Aug 10, 2017)

A note on moderating...

I've been pretty clear in the past that I moderate with a light hand. I basically ban the actual spammers and outright hate speech and let the community resolve otherwise as it likes. It's not my job to make everyone get along. It's not my job to tell people they can't disagree with someone or to protect people from having their feelings hurt. I consider this place like a pub. Some people are going to swear and b!tch about their wives, some people are going to get into arguments. If you don't want to talk to someone, that's fine, don't. If you stand up on your barstool and start shouting for everyone to pay attention to you, and you're posting factually incorrect stuff all the time, I'm going to be a little more lenient of people who are putting up with it. This isn't a conspiracy community. This isn't a soapbox with a captive audience where you get to dictate endlessly and everyone has to listen and only support you and protect your ideas.

I tolerate a moderate amount of rudeness and crassness, this isn't Sunday School. If for no other reason than, this is a volunteer task and the more strict I have to be about conduct, the more sh!t I'm going to have to moderate.

*I do draw the line some place before actual death threats and death wishes,* obsessive name-calling, and deliberate drama stirring. Can't be doing that, no matter how upset you are that someone doesn't like your ideas. Also, abusing the "report" button because you want attention to your issue, that I now have to go through and process an inordinate amount of one-by-one on a (Canadian) holiday.

I put Rishimaze on a bit of a temporary timeout to cool down. Despite him obviously feeling like a victim and feeling like it's okay to respond however he likes, he's actually acting much worse than the behavior he's critical of. I sympathize with the feeling of wanting to share your ideas and have a parental figure protect them from discussion and "punish" the people they feel are "bad", but, that's not here. It does not surprise me that he has, many times in the past, demanded to be protected from criticism, to the point of futility, and had to leave communities because he can't handle it. In general, my experience with this personality, it's never enough, it always comes to stricter and stricter demands of protection and eventual dramatic departure regardless. Usually because of their mental state, or something else in their lives. Hopefully I'm wrong. Hopefully this timeout lets cooler heads prevail.

Remy has been warned in the past and generally knows where the line is, and stays annoyingly close to it. He's been crass but he's not posting garbage or whole posts antagonizing others, and generally takes time out of his day to provide useful, unsugarcoated advice which is usually factual. I would generally describe it to be the infamous Dutch Bluntness. I would rather it be done in a more positive way, but again, provided it stays shy of bullying or hatred, it's up to each person if they want to engage with him or not. I know some don't, or, drop out of the conversation if he's gotten too rude for them.


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## kennybobby (Aug 10, 2012)

Thanks Matt, time to ignore the zoo and enjoy your holiday weekend.


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## Deane (Mar 21, 2020)

remy_martian said:


> yup
> View attachment 130881
> 
> 
> ...


Remy, tell us again why hub motors are less desireable. Unsprung weight?


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## remy_martian (Feb 4, 2019)

That's been discussed to death in other threads


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## rishimaze (May 23, 2021)

MattsAwesomeStuff said:


> I put Rishimaze on a bit of a temporary timeout to cool down. Despite him obviously feeling like a victim and feeling like it's okay to respond however he likes, he's actually acting much worse than the behavior he's critical of. I sympathize with the feeling of wanting to share your ideas and have a parental figure protect them from discussion and "punish" the people they feel are "bad", but, that's not here. It does not surprise me that he has, many times in the past, demanded to be protected from criticism, to the point of futility, and had to leave communities because he can't handle it. In general, my experience with this personality, it's never enough, it always comes to stricter and stricter demands of protection and eventual dramatic departure regardless. Usually because of their mental state, or something else in their lives. Hopefully I'm wrong. Hopefully this timeout lets cooler heads prevail.


Good job! Punish the victim and do NOTHING to the perpetrator!!! Excellent work on accomplishing nothing good at all and letting the BAD GUY go free and punishing his latest victim instead!!! You did nothing of value to stop the bully harassing people!!! All you did was exonerate the perpetrator!!! Do you seriously think a warning has any effect at all on someone like him??? The person to BAN is Remi!!! NOT HIS VICTIMS!!!


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## MattsAwesomeStuff (Aug 10, 2017)

It appears a 1 week timeout was insufficient.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> It appears a 1 week timeout was insufficient.


Apparently. To date I have only had spammers in my "ignore" list, but I have just added _rishimaze_, in case he gets unbanned.

IPM outrunners is still a valid topic for a discussion of theory, if any wants to pursue it in a constructive manner, but that seems unlikely.

Anyone interested in large outer-rotor ("outrunner") motors for road vehicles might want to look at the larger motors from TM4, which are offered in "direct drive" (direct to axle without other transmission) configurations under the SUMO product name as part of the Dana TM4 line. Interestingly, the SUMO MD is described by the manufacturer as having both of these features:

Reluctance-assisted permanent magnet
Outer rotor topology for maximum torque density
An announcement explains that 


Dana TM4 said:


> Until now, the main rotor technology found in TM4’s electric motors was based on surface mounted permanent magnets. The desire to limit the use of rare-earth magnets has resulted in a technology choice that leverages the reluctance torque of TM4’s external rotor design and decreases by 25% the use of these elements. By substituting some of the magnets with soft magnetic composites (SMCs), variable reluctance adds *up to 45% extra torque and operating speed* compared with previous technology in same package dimensions.


This is still a surface PM outer rotor, despite this change.


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## MattsAwesomeStuff (Aug 10, 2017)

brian_ said:


> Apparently. To date I have only had spammers in my "ignore" list, but I have just added _rishimaze_, in case he gets unbanned.


I gave him another week to cooldown. I suppose we're on baseball rules now, because the third time he starts stirring drama it'll be permanent.

It does not surprise me. As I said, this type of person who claims to want to avoid drama, stirs it up higher and higher, wants more and more protection, which is never enough, and eventually leaves when their impossible standard is not met. I'm happy to be wrong.


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