Revolt RV-series motor review and comparisons

Electric Motors and Controllers
John in CR   100 GW

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 23 2020 11:34pm

ElectricGod wrote:
Jan 23 2020 10:44pm
On a side note..John, Lars and Madden...I forgive you!
There's nothing to forgive, since we didn't really do anything. That's what sucks about the history being deleted, since none of us can go back and read thru with a calm perspective to see where we may have gone wrong too. There certainly wasn't more than soft prodding done by those you're forgiving, and in that most recent locked thread it was at or near zero.

We (and I think it's ok to speak for the others in this regard) forgive you too with no hard feelings on anyone's part I hope, though I do still say the name is a problem, not a huge one, but it does turn away some of the real gurus as evidenced by their absence from your threads despite some interesting topics.

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 23 2020 11:37pm

sn0wchyld wrote:
Jan 23 2020 5:13pm
John in CR wrote:
Jan 23 2020 11:29am
To calculate power in using phase amps I think you'd have to multiply it by the "apparent voltage" that the motor "sees", something I have no idea (or need) how to measure. It's simple... battery Voltage while running times battery Current. Since no load current is so low the copper losses are minuscule and can be ignored, so the no load power (as long as you don't have gearing or a tire to turn, so no windage losses) represents the iron core losses (also ignoring friction losses of the bearings, which should also be minimal) at that rpm. That amount of heat is incurred whether or not the motor is under power. The number of turns of copper on the stator or copper fill % have nothing to do with this. These losses increase in a fairly linear manner with rpm after the initial plateau relating to (I believe) cogging torque is overcome. While this is an over-simplification of the hysteresis and eddy current losses in the iron and magnets it gives a basic idea of why no-load losses are important to us as they give us an idea of the maximum rpm we'd want to run the motor and peak efficiency.

Peak efficiency is the point where while under load the copper losses and iron losses are equal.

If the no load current has improved, then other than less friction losses in the bearings if they where changed, the improvement is coming from the controller...probably mostly due to the Nuc controller's hall placement correction, since there's been no change in the magnetic circuit (steel and magnets) of the motor. The big operating benefit of the motor rework is in all the additional copper fit on the stator teeth, because that reduces copper losses, the primary source of loss in our motors while in use. That means it runs cooler at any given power level (assuming heat dissipation is unchanged), so it's capable of handling more current and therefore make more power at a given rpm (as long as it remains below the current saturation point of the stator, which is unchanged from before).
main thought re rewind itself helping is a higher turn count will lower the rpm (presuming testing done at same voltage) which will also lower no load loss, if only because of reduced rpm. dont want to go saying the nuk has made x improvement if the turncount is doubled form the last 'stock' test :P
Good point. All we need is no-load power in at the same rpm for valid comparisons.

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Re: Revolt RV-series motor review and comparisons

Post by larsb » Jan 24 2020 10:56am

John in CR wrote:
Jan 23 2020 11:34pm
ElectricGod wrote:
Jan 23 2020 10:44pm
On a side note..John, Lars and Madden...I forgive you!
There's nothing to forgive, since we didn't really do anything. That's what sucks about the history being deleted, since none of us can go back and read thru with a calm perspective to see where we may have gone wrong too. There certainly wasn't more than soft prodding done by those you're forgiving, and in that most recent locked thread it was at or near zero.
Agreed, it’s like Homer forgiving his lobster for being eaten. In order to improve the situation Homer should instead stop eating it.. seriously EG,what are you thinking?

http://www.youtube.com/watch?v=ykNSoJsPgYU&t=3m2s
Last edited by larsb on Jan 24 2020 2:50pm, edited 1 time in total.
Ride on!

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spinningmagnets   100 GW

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Re: Revolt RV-series motor review and comparisons

Post by spinningmagnets » Jan 24 2020 11:04am

Hey, Lars. I've read that previous post twice, and I'm trying hard to find the part about electric motors. It sort of sounds off topic, but...I don't want to be accused of censoring valuable electric motor posts...

Have at it, fellas...(*grabs popcorn and takes a comfortable seat)

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Re: Revolt RV-series motor review and comparisons

Post by larsb » Jan 24 2020 11:11am

I forgive you, after all it’s friday.

EDIT: point taken. I still have a quite good BS to fact ratio though :wink:
Ride on!

John in CR   100 GW

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 24 2020 12:22pm

spinningmagnets wrote:
Jan 24 2020 11:04am
Have at it, fellas...(*grabs popcorn and takes a comfortable seat)
:bigthumb: Everyone is playing nice. If history repeats itself the real fun begins without actual rule breaking.

If you need something to censor in the meantime, please go teach people the difference between brake and break, along with your and you're. If you want to get fancy then throw yore in there too. Oops almost forgot there, their and they're. People not understanding the difference is as unforgivable as today's lack of proper phone etiquette (at least down here it's miserable).

Sorry for the OT EG. That you can hopefully forgive me for....Yeah, I know I shouldn't end a sentence with "for", but this is informal discussion so I don't think it's technically incorrect.
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jan 24 2020 2:52pm

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jan 24 2020 2:57pm

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fechter   100 GW

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Re: Revolt RV-series motor review and comparisons

Post by fechter » Jan 24 2020 5:36pm

Exact measurements of the losses will be hard to do. Measuring the no-load power will be a pretty close estimate of the iron losses.
To know the copper losses you need a way to measure the output power (mechanical).
"One test is worth a thousand opinions"

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Re: Revolt RV-series motor review and comparisons

Post by thepronghorn » Jan 24 2020 5:46pm

When people (including me) have said that peak efficiency is when copper and iron losses are matched, we are basing it on approximating iron losses as proportional to the square of rpm just as copper losses are proportional to the square of torque.

This does ignore hysteresis losses which are directly proportional to rpm, so this approximation is only somewhat accurate. At the higher powers that this rule is often applied, I feel it is an ok approximation since eddy current losses are usually fairly dominant.

It does make intuitive sense that if the order of the speed and torque dependent losses is the same, then maximizing Pout for a given Ploss would mean equal speed and torque losses. I did actually do the math by hand just now to derive this, but my scribbles are too ugly to post here. I can probably rewrite it and post it if you all want.

As people have said numerous times in this thread, all the measurements we need for a good characterization of a motor are: Kv (speed constant usually in rpm/V), Rphase (phase to phase resistance), and no-load power at two different rpms (achieved by measuring battery power at two different Vrms into a free spinning motor).

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jan 24 2020 6:59pm

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John in CR   100 GW

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 24 2020 7:13pm

thepronghorn wrote:
Jan 24 2020 5:46pm
...iron losses as proportional to the square of rpm...
That part is a new one for me. I always thought iron losses increase in amostly linear. Below is a quick graph I did using Miles' Motor Comparison Spreadsheet with a HubMonster hubmotor as the motor, for which the input numbers I provided to Miles which I know to be conservative as confirmed by Ohbse's separate measurements. The low iron losses combined with the low combined phase-to-phase resistance of the 2 motor halves at 16mOhms results in a predicted peak efficiency of over 95% at almost 10,000W output at 1500rpm with total heat losses of less than 500W, which is easily shed at that speed with a stock sealed motor. That's the support for my so often claimed "best HubMotor ever made". It's a real shame that so many considered the factory test report claim of 94% peak efficiency as too good to be true, so I couldn't generate enough interest on the forum to convince the factory to extend production since they ran into the same issue and didn't really understand the motor well enough to run it with dual higher power controllers.

This seems pretty close to linear to me:
Graph of HubMonster Iron losses.JPG
Graph of HubMonster Iron losses.JPG (41.64 KiB) Viewed 752 times

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 24 2020 7:27pm

ElectricGod wrote:
Jan 24 2020 2:57pm
On the topic of iron losses vs copper losses...
How would I measure these in an easy way?
I have a milliohm meter, 3 o-scopes, various ways to read current and temperature.
What can I do with them to find that crossing point between these 2 losses?
Iron losses is simple, and at any rpm is the no-load battery current X voltage. If you want to get more exact subtract the power to run the controller.

Didn't you get a display from Nucular? It calculates Kv of the motor, and you can set the wheel size so it's reporting rpm as the speed though I bet you can set up the display to show rpm too. You can do the same with a Cycle Analyst. Even a few $ bicycle speedometer/computer should be able to handle a pretty good rpm in the same manner.

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jan 24 2020 7:49pm

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Re: Revolt RV-series motor review and comparisons

Post by thepronghorn » Jan 24 2020 8:30pm

John in CR wrote:
Jan 24 2020 7:13pm
thepronghorn wrote:
Jan 24 2020 5:46pm
...iron losses as proportional to the square of rpm...
That part is a new one for me. I always thought iron losses increase in amostly linear. Below is a quick graph I did using Miles' Motor Comparison Spreadsheet with a HubMonster hubmotor as the motor, for which the input numbers I provided to Miles which I know to be conservative as confirmed by Ohbse's separate measurements. The low iron losses combined with the low combined phase-to-phase resistance of the 2 motor halves at 16mOhms results in a predicted peak efficiency of over 95% at almost 10,000W output at 1500rpm with total heat losses of less than 500W, which is easily shed at that speed with a stock sealed motor. That's the support for my so often claimed "best HubMotor ever made". It's a real shame that so many considered the factory test report claim of 94% peak efficiency as too good to be true, so I couldn't generate enough interest on the forum to convince the factory to extend production since they ran into the same issue and didn't really understand the motor well enough to run it with dual higher power controllers.

This seems pretty close to linear to me:
Graph of HubMonster Iron losses.JPG
I guess that looks kind of linear. It also looks VERY 2nd order (because Miles' spreadsheet calculates a 1st and 2nd order component). I looked at the spreadsheet again, and it did strike me that the hysteresis drag torque constants were higher than I remembered, so maybe ignoring the 1st order component of iron losses is not a good approximation... Maybe I should stop spreading the myth that peak efficiency is when copper and iron losses are equal. Time for a new thread ala zombiess "high Kv is better aka power transfer theorem" or whatever it was.

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 24 2020 8:44pm

ElectricGod wrote:
Jan 24 2020 6:59pm
NOTE:
Things may have been said multiple times previously.
When people are slamming others, attacking them and making negative comments, actual collaboration comes to a screeching halt!
I've always wanted whatever I do here or in any thread I post in to be collaborative and helpful to everyone.

In that spirit...
I volunteer with 2 other people and teach middle school kids about building EV's.
We pay for nearly everything ourselves and don't personally benefit in any way from those classes.
I used to be a volunteer fire fighter for 6 years.
I've sought out, most of my adult life, places or opportunities where I could help people.
Even my job in software testing is for a company that does this!
That's why I make threads like this and spend my own time and money on EV related things.
This motor, doesn't belong to me. The owner...Milan...asked me to check over his EV and help him make it better.
I volunteered to rewind his motor for him for free. All I asked is he buy the wire and other parts needed to improve it.
I've rewound it 4 times and each time I get the wind a bit better. All of my efforts for him are free!
I've made metal parts, modded many motors and controllers, built battery packs and other EV parts for quite a lot of people.
...All for the cost of the materials needed only.
I make zero money for my services and that IS how I want it to be!
That's who I am.

In that spirit...lets keep this collaborative, helpful, friendly and on topic always.
Thank you!
How someone acts in the real world is often quite different from their online persona, so what you do outside of the matrix is really irrelevant to interaction here on ES. In fact, that list immediately above, has a familiar ring to it in my view...a bit like the guys whose first step in a disagreement here is to rattle off their education and degrees. In my experience that's shown to be a big red flag...not that education, degrees and experience aren't great, but those who feel the need to bring it up to support their side of a disagreement generally means they don't have a substantive argument.

You can tell us to stay on topic all you want, but just like a conversation in person can drift away the same can, often does, and will happen here. With regard to you in particular expect teachable moments, because those of us who've been the repeated subjects of your attacks (not the source of the attacks) already see your switch about to flip, and when it does there will be quite frank off topic conversation. We're going to teach you to behave around here like you claim to do in person. I give you the benefit of the doubt and think you don't realize what you've done repeatedly, so I see change as possible.

Tip-toeing around the subject to avoid a powder keg from going off with strict adherence to "on topic only" is no solution. Warnings and thread locking clearly hasn't worked, and I believe it's because everything was deleted making it impossible to see the error in your ways after you've calmed down.

Before you reply, please understand that there's no attack whatsoever in this post, and there's no subtle attempt to stir the pot. Instead of trying to use sarcasm and wit to make my point, which would have surely set you off, I took the time to try word this with only group harmony in mind. If you take it otherwise, wait awhile and read it again before responding.

The ball is in your court with a number of people waiting to see whether SpinningMagnets' bowl of popcorn was worth preparing. I'm an optimist and give it only a 50/50 chance.

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jan 24 2020 8:49pm

thepronghorn wrote:
Jan 24 2020 8:30pm
...Maybe I should stop spreading the myth that peak efficiency is when copper and iron losses are equal...
Why are you calling it a myth? As long as you add "for a given voltage" it's true AFAIC and I proved it to myself with a quick bit of trial and error using the spreadsheet.

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sn0wchyld   1 MW

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Re: Revolt RV-series motor review and comparisons

Post by sn0wchyld » Jan 24 2020 10:37pm

ElectricGod wrote:
Jan 23 2020 10:44pm
sn0wchyld wrote:
Jan 23 2020 5:13pm
main thought re rewind itself helping is a higher turn count will lower the rpm (presuming testing done at same voltage) which will also lower no load loss, if only because of reduced rpm. dont want to go saying the nuk has made x improvement if the turncount is doubled form the last 'stock' test :P
Zero stock testing done...so who knows.
I certainly do NOT trust anything Revolt might say!
They don't exactly present you with honesty and real motor specs!
ALL of their motors I have, need improvements and have various issues with quality.
I did the work to fix the Revolt factory issues in this motor.
Let's look at what I get and ignore Revolts factory specs.
They are probably BS anyway!

My turn count is 6 turns, WYE and something like 80 kv...TBD. The factory count was 12 turns, 67kv and delta. I was never going to duplicate the 67kv wind on the motor from the factory. Never mind that I have more than 3X copper cross section than the factory wind. There's too many things that have changed IMHO to be able to do a comparison with the factory wind.

IF you guys have real stuff I can do or test...post away!
I am not all knowing. I do NOT know everything there is to know.
I am open to doing all sorts of stuff to measure how good my RV-160-SH is doing.

There is one limiting factor. I did this rewind for a friend in San Francisco. He's eagerly awaiting the motor and controller.
He knows the motor is done and that I need to do some minor setting changes in the controller before sending all of it to him.
I won't put him off for very long before sending off his stuff.

On a side note..John, Lars and Madden...I forgive you!
Lets work together and be productive and friendly.
There is no need for bashing people.
I'd be willing to remove you from my foes list.
too bad re the controller... Do you happen to have a similar spec/make trap controller kicking around? its hardly a uni-variant scientific study but will still give some indication of the difference between the nuk and some chinese cheap and cheerfull controller... given its a higher kv it suggests that the nuk may have something to do with it, though the change of bearings may be as if not more significant (IIRC Vasili found the bearing was causing most of the 1kw losses above like 5k rpm or similar). Is the test still at the same voltage? in which case the higher rpm and lower no load is an even bigger change from stock... The big test though would be the no load at 2 different voltages - enabling the use of miles's spreadsheet and a more complete understanding of the motors capabilities (if only with major upgrades form stock :P )
.

edit:
is the motor stable enough to run without the skirt bearing? or alternatively to add a 2nd skirt bearing (even if only attached and not properly in use) and see how much it increases the no load? that would atleast tell us the impact of the skirt bearing... though would require machining a mount for it to go (say) on the back side of the motor.

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Re: Revolt RV-series motor review and comparisons

Post by larsb » Jan 25 2020 4:10am

ElectricGod wrote:
Jan 24 2020 6:59pm
NOTE:
Things may have been said multiple times previously.
When people are slamming others, attacking them and making negative comments, actual collaboration comes to a screeching halt!
I've always wanted whatever I do here or in any thread I post in to be collaborative and helpful to everyone.
We’ve been through this before: attacks and negative comments are bad of course but a clear message that ”1+1 does not equal three” is not an attack.

In just the last few posts you were again not understanding that if calculated power out is higher than power in then you are wrong. You didn’t throw a fit this time, was it because you saw the error this time? Or wasn’t it an ”attack” ?

Either way you didn't acknowledge your error. I am afraid you just look the other way, don't learn anything - then it gets ridiculous to be "forgiven" - for what?

I can say that some things were interesting in this thread, one example was noload current between two powervelocity controllers was something like 50% higher with the same motor. Was that measurement correct, based on dc volts * dc amps and measured with a good DMM?
If so, then one of these controllers is a crappy match for the tested motor and this is (if correct) interesting. It then makes all noload testing become questionable as well as the quality of the controller.
Ride on!

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jan 25 2020 4:45pm

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jan 25 2020 4:54pm

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Re: Revolt RV-series motor review and comparisons

Post by coleasterling » Jan 25 2020 5:41pm

I wouldn't normally get in this, but dude. You need to calm down. Let it go.

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Re: Revolt RV-series motor review and comparisons

Post by mark5 » Jan 25 2020 5:41pm

spinningmagnets recused himself from moderating this topic so that might leave only me here.

I'm not going to lock it or delete content. At the same time, people should be careful not to write anything they might later regret because that'll also stay here for the record. I'm not going to sanitize it.

Finally, as far as I've seen, tradition here is no one owns a thread. Technical content anyone writes is open for review and criticism by fellow members.

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Re: Revolt RV-series motor review and comparisons

Post by sn0wchyld » Jan 25 2020 10:14pm

ElectricGod wrote:
Jan 25 2020 4:45pm
sn0wchyld wrote:
Jan 24 2020 10:37pm
too bad re the controller... Do you happen to have a similar spec/make trap controller kicking around? its hardly a uni-variant scientific study but will still give some indication of the difference between the nuk and some chinese cheap and cheerfull controller... given its a higher kv it suggests that the nuk may have something to do with it, though the change of bearings may be as if not more significant (IIRC Vasili found the bearing was causing most of the 1kw losses above like 5k rpm or similar). Is the test still at the same voltage? in which case the higher rpm and lower no load is an even bigger change from stock... The big test though would be the no load at 2 different voltages - enabling the use of miles's spreadsheet and a more complete understanding of the motors capabilities (if only with major upgrades form stock :P )
.

edit:
is the motor stable enough to run without the skirt bearing? or alternatively to add a 2nd skirt bearing (even if only attached and not properly in use) and see how much it increases the no load? that would atleast tell us the impact of the skirt bearing... though would require machining a mount for it to go (say) on the back side of the motor.
I'm not taking the motor apart for any reason except I have a problem with it.
What I can tell you is sealed skirt bearing turns smoothly with very little resistance.
While this doesn't really mean much, it's the best I'm going to do in this regard.
The factory NSK bearing was shielded and used, but not crunchy from dirt incursion.
The new sealed NSK skirt bearing turned just as easily despite the resistance from the seals and being new.

I do have a Kelly trap controller that I've never used or messed with. I want to try it out, so I can sell it off.
This might be the time for that "test" run of the controller.
I care a lot less about trying out trap on this motor than I do about trying 48v and 66v on the Nucular.
All results so far on the Nucular have been at 82v...which it the highest safe voltage for it.
Iron losses tend to increase with increase of pack voltage or increase in motor RPM.
I suspect that at lower pack voltage iron losses will also be less, but maybe not significantly so.
what I was suggesting was to machine up a bearing ring (likely outer ring) that can seat a 2nd skirt bearing to the outside of the motor (easy if you have a lathe?) - then its just a matter of keeping the inner ring of that bearing stationary and spinning it up - wouldn't require taking the motor apart (cant blame ya for not wanting to do that again...) just bolting on a circular bit of ally with bearing seated inside to the outer side of the motor... would give an easy way to test the impact of that bearing at peak rpm. May not be worth the trouble but would still be interesting imo to narrow down and see where that 400w in losses are coming from. same re trap controller - more just a curiosity to isolate benefits from rebuild/new bearings vs new controller. if we can get a rough idea of bearing loss + controller loss (or reduction there of) we can get closer to estimating iron losses...

And seriously dude, chill the f* out... even if they were personal attacks ( and this is not me conceding they are- if this stuff qualifies as personal attacks warranting that kind of response then honestly you must have lead a very sheltered life - theres nothing wrong with that but seriously mate - this wouldn't even be a 1/10 on my experience ) the response is simply uncalled for - just make your arguments/expressions on what you think is right and let the rest go.

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Re: Revolt RV-series motor review and comparisons

Post by fechter » Jan 25 2020 10:44pm

mark5 wrote:
Jan 25 2020 5:41pm
spinningmagnets recused himself from moderating this topic so that might leave only me here.

I'm not going to lock it or delete content. At the same time, people should be careful not to write anything they might later regret because that'll also stay here for the record. I'm not going to sanitize it.

Finally, as far as I've seen, tradition here is no one owns a thread. Technical content anyone writes is open for review and criticism by fellow members.
Thanks Mark. I support this approach.

I know all of the members involved to some extent and they have all provided valuable technical input over many years. I'm sure people reading those threads appreciate the content as well.

But PLEASE lets keep these topics nice to read later. Please stay with the technical stuff. If you have some personal rant, please do it by PM and spare the rest of us. The moderatos don't have time to go sanitizing threads later even if they decided they wanted to. It's hard enough to keep up with the spammers.
"One test is worth a thousand opinions"

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