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  • BroMikey
    replied
    Another example of a drill press rotor failed device mess, ''off by only'' 50 or 30 thousandths here and there on the "X" and "Y" axis the green circles can represent the stationary opposition positions.


    http://flyer.thenetteam.net/MackMtr/rotormess2.jpg

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  • BroMikey
    replied
    Bye's make shift rotor art work. Frame it Bye.


    http://flyer.thenetteam.net/MackMtr/rotormess.jpg

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  • BroMikey
    replied
    Also the quality of the magnets can affect the field coming out of the ends. If cheap irregular magnets are used you might want more of them so as to have some number of them all the same. Bye you have to have accuracy at tdc. You need good materials.

    You can't use cheap stuff and high dollar meters. You can not randomly place opposition magnets around the outside. 1/2 degree for such a small wheel might be a few thousandths. You can not hammer and nail this stuff together without some sort of machining process.

    Random is poorly done and no machine involved is going to have at best limited progress if any. Maybe this is what you had in mind?

    It is easy to fail using low accuracy equipment to construct geometrical shapes to interact with invisible magnetic fields. Misplace opposition magnets will perform right at one station lowering the draw while the next location around the circles hinders.

    ONE OF MY ROTORS HAD 1 MAGNET A FEW THOUSANDTHS FURTHER AWAY FROM THE CENTER THAN THE OTHER AND THIS THREW THE WHOLE THING OFF. IT MUST BE MACHINED.

    You must be very close to use 10 positions all at the same time.

    I have used only 2 positions, one exactly (or almost) right across from the other and have been unable to get the same response when turning the rotor 180 degrees. The amount of movement for these magnets is so small and will be impossible to move them later.

    If you work long and hard you might get 2 magnets on a rotor to balance against two outside neutralization poles. Maybe. Good luck with that. 10 stations? Never.
    Last edited by BroMikey; Yesterday, 03:36 AM.

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  • bistander
    replied
    Contrary to some BS you might see on this thread, positional and dimensional tolerances are not critical to .001th's of inches in large air gap PM machines especially when most of the magnetic circuit is air anyway. High quality and well balanced machinery is always desirable but hardly necessary for every 7th grade science experiment.

    Those that question what I just wrote are invited to do the tolerance analysis and/or experimental proof to show otherwise.
    bi

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  • BroMikey
    replied
    One very important things everyone is leaving out. Unless your rotor magnets are placed perfectly within 1 thousandths of an inch opposition magnet losses could occur. The reason for this is that each time a rotor magnet passes a core and the extra opposition magnet is placed to interact creating balance, the next magnet if off could take away any gains.

    It is 100% imperative that the critical tolerance be reached especially when 10 or 12 stations are the design plan. I hope this limited entry will get the wheels turning upstairs. High precision machining is a requirement to achieve any kind of success. 1 degree off of TDC positioning will throw out the balance, so to speak. TDC must be the same for each fixed and rotating. The slightest adjustment could mean failure against randomly positioned.
    Last edited by BroMikey; Yesterday, 12:42 AM.

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  • bistander
    replied
    Originally posted by Turion View Post
    The effect of additional cores on the amp draw of the motor is not additive. It is not a straight line graph. Each additional coil has a bit greater affect on amp draw than the previous coil. It’s a curve and I don’t know how severe that curve is. Add one coil and the affect is barely measurable. Add 4 coils and get a 7 amp increase. Add 8 additional coils and the increase is to over 27 amps. The magnets eliminate that increase. But what is increasing?
    Our resident expert has stated many times that cogging “goes away” at speed, so it can’t POSSIBLY be cogging, although just recently he posted that the magnets “mitigate” something he has insisted doesn’t exist. I wonder which time he was wrong? This is why actually building things is far more important that spouting Wikipedia definitions.
    Each additional coil has a bit greater affect on amp draw than the previous coil.
    Hi Turion,

    I think I disagree with your statement but would like you to clarify coils vs cores before I test it.
    Thanks
    I have never said "cogging goes away at speed". Cogging becomes less noticeable to the point of being insignificant at higher RPM.

    And what don't you understand about cogging mitigation at start-up and low speed then running and testing at a higher constant speed? Where's the contradiction? Just set your "opposition" or "neutralization" magnets to your best optimum position and then run the test.
    bi

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  • bistander
    replied
    Originally posted by BroMikey View Post
    Note" Important Notation!!

    A large motor rotating 1 magnet close to 1 core will not show up on the amp draw when introducing an opposing magnet. Let's just say the difference in amp draw is difficult to detect until the motor gets up to a 70% load. Many magnets and many cores must be in place to load the motor up. In Bye's case he is only using 2% load from the motor. Changes are much harder to detect.

    I suggest a pulse mode controller such as is found on a scooter. This form of motor control is better. Connecting direct to a battery is not a good choice for such small loads.

    However if the approx run load ma is known the investigator can switch in and out of the circuit "at speed" this device, so as not to peg the needle on start up. Now you can detect increases properly.

    https://i.ebayimg.com/images/a/T2eC1...~~/s-l1600.jpg

    As investigator you don't want to fool yourself by leaving out the obvious.

    So let's say it only went down 50ma when using the opposition magnet. Times 10 = 500ma for 10 coils and 10 cores plus 10 opposition magnets. The motor may only run at 500ma and you saved 500ma. This is a great savings, and double the usage may burn out the motor.

    Using a 5 amp meter a 500ma decrease will show up if you look closely but accuracy is poor and a 50ma decrease will not be noticeable.

    Also running with no coil is not the same test as everyone else. Making tests on a small scale is attractive yet having the same setup is critical to a true assessment of others projects.
    In Bye's case he is only using 2% load from the motor.
    The motor I'm using is a small 12/24V PMDC motor called a 775 size. Similar motors found on Amazon indicate a rating of 80 watts. With my accurate ammeter I can go up to 3 amperes, so 36 or 72 watts at 12 or 24 V.

    IMG_20210507_095842419.jpg

    I use a PWM motor controller to adjust RPM and limit current as not to peg ammeter on acceleration.

    IMG_20210507_100218848.jpg

    https://i.ebayimg.com/images/a/T2eC1...~~/s-l1600.jpg

    Using a 5 amp meter a 500ma decrease will show up if you look closely but accuracy is poor and a 50ma decrease will not be noticeable.
    I use a lab grade ammeter not a cheap eBay panel meter. It can indicate milliampere changes on scales from 100 to 3000 mA.

    IMG_20210507_100054896.jpg
    A large motor rotating 1 magnet close to 1 core will not show up on the amp draw when introducing an opposing magnet.
    So far, I've been running 4 magnets on the rotor. I intend to change to 12, maybe today. I have tested using one and two cores. I made provisions to use 3 cores with 3 opposition magnets if I want to go that far, with 12 rotor magnets.

    The introduction of the opposition magnet will not show on the amp draw not due to a large motor, but because it does not reduce core loss (magnetic drag).

    Coils are irrelevant to core loss/magnetic drag so should be left out of the test. If they are needed to support cores, all strands need to be disconnected. I encourage all to test with and without coils, but without coils is the true test of cores and "opposition" or "neutralization" magnets.
    bi

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  • bistander
    replied
    Originally posted by Turion View Post
    I don’t care. If I can reduce the amp draw of the motor from 27 amps down to 7-9 amps that’s all that matters. And I can. I have. And I will continue to do so.
    You still think there were 6 cells in the LiFePO4 12 volt battery? You just don't care about truth and will continue to spread falsehoods instead of spending a few minutes to do a 7th grade science experiment and learn something. A true researcher.
    Good luck,
    bi

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  • Turion
    replied
    I don’t care. If I can reduce the amp draw of the motor from 27 amps down to 7-9 amps that’s all that matters. And I can. I have. And I will continue to do so.

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  • bistander
    replied
    Originally posted by Turion View Post
    Let me get this straight. With the exact setup you describe. The motor is running at rated speed and drawing amps. As you adjust the magnet that amp draw goes down. Now when you withdraw the magnet the amp draw only has two directions it can go. Down, which makes absolutely NO sense, since it was higher BEFORE you adjusted the magnet in the first place and you just moved it DOWN with your adjustment. Or it can go back up to where it was before the adjustment to the magnet was put in place. Which way does it go? But to make it perfectly clear, I have never bothered to fool with it this way. I have a specific amp draw and I adjust the magnet to reduce it. If removing the magnet somehow then makes the amp draw go down even MORE, what’s wrong with that? I doubt that is possible, but if it does then good for me!
    No you don't have it straight. I never said, "adjust the magnet that amp draw goes down", when "The motor is running at rated speed and drawing amps". I said to set the opposition magnet to "minimize cogging". I don't care how you do that, but I need that as the condition which you claim the motor will draw minimum current at constant RPM and constant voltage as the starting point for the test. Then, when you witness no increase in current while backing off the magnet, you'll realize how much benefit it was actually providing.

    Simple as that.

    Originally posted by Turion View Post
    If removing the magnet somehow then makes the amp draw go down ...
    I doubt that is possible, but if it does then good for me!
    You'll not know unless you try it.

    Reduction was minimal at my frequencies so I hesitate to claim you'll see reduced current when backing off the magnet. But knowing magnetic losses are frequency dependent, and having alex speak of opposition magnet heating, I suspect it is possible.

    Again, the real point is to demonstrate that your magnetic neutralization or opposition magnets do not reduce magnetic drag. The magnetic drag was there before you added the magnets, is there with the magnets and is still there when you back off the magnets.
    bi

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  • Turion
    replied
    Let me get this straight. With the exact setup you describe. The motor is running at rated speed and drawing amps. As you adjust the magnet that amp draw goes down. Now when you withdraw the magnet the amp draw only has two directions it can go. Down, which makes absolutely NO sense, since it was higher BEFORE you adjusted the magnet in the first place and you just moved it DOWN with your adjustment. Or it can go back up to where it was before the adjustment to the magnet was put in place. Which way does it go? But to make it perfectly clear, I have never bothered to fool with it this way. I have a specific amp draw and I adjust the magnet to reduce it. If removing the magnet somehow then makes the amp draw go down even MORE, what’s wrong with that? I doubt that is possible, but if it does then good for me!

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  • bistander
    replied
    Originally posted by Turion View Post
    Go back and look at the videos we posted at Greyland’s shop. We showed the amp draw with NO coils and then again after we had added 4 coils. It was ALREADY up to 13 or 14 amps and we could no longer use the power supply to run the motor like we did in the FIRST video because it was rated for 14 amps and would kick off.

    You have NO idea how I “adjust” my opposition magnets, so what YOU said doesn’t apply. They are ALWAYS adjusted with the motor running at speed. Choking on that cake yet?
    You're not talking about the same conditions. Do the 7th grade science experiment in simplist form. One core in place all the time. No coil. One opposition magnet at 180 from that core. Opposition magnet adjusted to minimize cogging. Now run it at constant RPM and constant voltage. Observe current as you back off the magnet.

    bi

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  • Turion
    replied
    Go back and look at the videos we posted at Greyland’s shop. We showed the amp draw with NO coils and then again after we had added 4 coils. It was ALREADY up to 13 or 14 amps and we could no longer use the power supply to run the motor like we did in the FIRST video because it was rated for 14 amps and would kick off.

    You have NO idea how I “adjust” my opposition magnets, so what YOU said doesn’t apply. They are ALWAYS adjusted with the motor running at speed. Choking on that cake yet?

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  • bistander
    replied
    Originally posted by Turion View Post

    Gee, how is it I am able to, in YOUR words, "mitigate cogging" with magnetic neutralization when you have been telling me for years that cogging goes away at speed? How is there any cogging to "mitigate"? You're trying to have your cake and eat it too. Careful you don't CHOKE on it.
    You set the magnet to mitigate cogging where cogging is noticeable, like at start-up and low speed acceleration.


    Originally posted by Turion View Post

    There is an attraction of the rotor magnet to the core material that the neutralizing magnet eliminates. I call it magnetic drag. You can call it lima beans for all I care, if YOU define magnetic drag as something else, or there is a "textbook definition" for 'magnetic drag." All that matters is that the amp draw of the prime mover is reduced when the neutralizing magnets are put in position. 27 amps without it. 9 amps with it. Those are facts. When the amp draw is there, and you adjust the magnet and take it away, it doesn't STAY AWAY when you remove the magnet. You have NO IDEA what you are talking about.
    You could learn to use the language and terminology of the science and subject. Look up "magnetic drag", "core loss", eddy current loss, hysteresis loss, Newton's Laws of Motion, etc.

    IF "All that matters is that the amp draw of the prime mover is reduced when the neutralizing magnets are put in position."

    ​​​​​​WHY doesn't the amp draw of the prime mover increase when the neutralizing magnet(s) are backed out of position?

    You say "When the amp draw is there, and you adjust the magnet and take it away, it doesn't STAY AWAY when you remove the magnet."

    Of course not.

    You say "27 amps without it."

    You also said "6 cells".

    Do you have proof, like video evidence, of "27 amps without it". All it takes is a few minutes to run my suggested test. But you won't do that will you? It's pretty obvious that you have the equipment, and skill to video record the ammeter, so the reason you won't run the simple "7th grade science experiment" is that you know the result is as I claim.
    bi
    ​​​​​​

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  • Turion
    replied
    Originally posted by bistander View Post

    Thereby showing that the neutralization magnet, although mitigating cogging, does not reduce magnetic drag. The magnetic drag was present when the neutralization magnet was in place, and remains there when the magnet is removed

    bi
    Gee, how is it I am able to, in YOUR words, "mitigate cogging" with magnetic neutralization when you have been telling me for years that cogging goes away at speed? How is there any cogging to "mitigate"? You're trying to have your cake and eat it too. Careful you don't CHOKE on it.

    There is an attraction of the rotor magnet to the core material that the neutralizing magnet eliminates. I call it magnetic drag. You can call it lima beans for all I care, if YOU define magnetic drag as something else, or there is a "textbook definition" for 'magnetic drag." All that matters is that the amp draw of the prime mover is reduced when the neutralizing magnets are put in position. 27 amps without it. 9 amps with it. Those are facts. When the amp draw is there, and you adjust the magnet and take it away, it doesn't STAY AWAY when you remove the magnet. You have NO IDEA what you are talking about.

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