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MaxAdventure
06-21-2010, 06:37 PM
Original Topic: Help with correctly poled magnets and alignment

My search skills aren't helping me today, I'm trying to find how to align my magnets on a motor build, and how to be sure I have the right magnets. When I say right, I mean that they are magnetized in the correct dimension. I'd sure appreciate a link - I've found some fascinating magnet reading, but not about how to test and place magnets for a motor. TIA!

wingnutt
06-25-2010, 02:43 PM
MA - If I understand your question correctly, you want to know how to orientate the magnets in the can by their north and south poles? If so it’s a pretty simple matter.
First, get two magnets and CAREFULLY bring them together (without them making contact!) end to end but only close enough to tell if the ends are attracting or repelling eachother. If they attract, mark one of the mating faces (using a sharpie or other permenant marker) with an 'N' and the mating face on the other magnet with an 'S'. If they repell eachother, then mark both with the same letter 'N' or 'S'. Keep one of the two magnets in your hand for comparison and finish marking the rest of your magnets. Now when you go to place them in the can you will want to see the letters alternate S, N, S, N, etc.
As far as a good way to hold and space them in the can, I have yet to try that part of motor building so I can't really help you out there. If I come across something I will let you know unless someone beats me to it.

MaxAdventure
06-25-2010, 03:08 PM
... If they repell eachother, then mark both with the same letter 'N' or 'S'. ...


thanks for the response!
While not actually part of the question, I was also wanting to know how to tell north from south, not that it really matters for a magnet build as you state. Even if you label them wrong by the method you describe, it will still work. As an aside, how does one tell north is really north? float the magnet and let it orient to the earth's poles?

Let me restate what I was asking:

Should the correct pole orientation on a magnet for a brushless outrunner be end to end, side to side, or front to back?

I had thought I'd noticed pole orientation through thickness (front to back) but my new magnets seem to have a different pole orientation than the original.

What happens if it's supposed to be side to side and I have front to back, or vise-versa?

Larry3215
06-25-2010, 04:24 PM
You want the poles facing the stator teeth and the can - not the magnets on either side.

A typical small motor magnet might be 5mm x 5mm x 2mm thick. One 5x5 side attaches to the rotating can and the opposite side faces the stator teeth.

You want the poles to be on the 5x5 sides.

If they are on one of the smaller ends - they wont work.

There used to be someone who made magnet spacers for the smaller sized CDrom type motors. I'll see if I can find a link.

Larry3215
06-25-2010, 04:34 PM
Check out these guys for parts and lots of building tips and tricks.

http://www.gobrushless.com/shop/

magnet spacers

http://www.gobrushless.com/shop/index.php?app=ccp0&ns=catshow&ref=accessories

http://www.strongrcmotors.com/Magnet%20Spacers.htm

more parts and info

http://www.strongrcmotors.com/

Basic info pages

http://www.bavaria-direct.co.za/models/motor_info.htm

Magnets

http://www.engconcepts.net/List_Of_Neodymium_Motor_Magnets.asp

http://www.supermagnetman.net/index.php?cPath=37&page=5

MaxAdventure
06-25-2010, 08:39 PM
Thanks again Larry!

using your links, I was able to find the specific sentence I needed:
"Only use magnets that are magnetized through their thickness."

from: http://www.bavaria-direct.co.za/models/faq.htm#Tips

And I did order these replacements from SuperMagnetMan based on Wattflyer member recommendations.

In reviewing what I ordered:
"General Magnet Type : Rectangle What are the dimensions? For rectangle shapes Length, width and thickness. Cylinders and discs diameter and length, etc. : 2mmx8mmx30mm What will be the direction of magnetization? : thickness"

It seems I've ordered the right thing, now I just have to rebuild my Z50 with the new magnets and get my heli put back together. They just seemed different when I played with them vs the ones currently in the motor.

Thanks again!

MaxAdventure
08-13-2010, 08:28 PM
Now I've reassembled the motor, but my CC Phoenix HV gets it to 'chatter' then shut down. It feels really stiff/mushy to turn by hand. I completely disassembled the motor again today to check for bad bearings and/or goo. The bearings are OK, I'll be replacing at least once as it isn't 100%, (it does turn freely, it's just you can tell it needs replacing)

Normally, motors seem to have various degrees of 'nochyness' as you rotate them. I do recall this one had some, even if it seemed a lot less. Now it feels more like there is some friction when you turn it, but I can hold the motor out of the case so nothing is rubbing and I feel it. It gets stronger the lower into the motor I go. are my replacement magnets too strong? I really don't know where to go with this now, bummed I'm not only out my motor but spent the money on the magnets and I can't get the motor to run.

CHELLIE
08-13-2010, 11:53 PM
Now I've reassembled the motor, but my CC Phoenix HV gets it to 'chatter' then shut down. It feels really stiff/mushy to turn by hand. I completely disassembled the motor again today to check for bad bearings and/or goo. The bearings are OK, I'll be replacing at least once as it isn't 100%, (it does turn freely, it's just you can tell it needs replacing)

Normally, motors seem to have various degrees of 'nochyness' as you rotate them. I do recall this one had some, even if it seemed a lot less. Now it feels more like there is some friction when you turn it, but I can hold the motor out of the case so nothing is rubbing and I feel it. It gets stronger the lower into the motor I go. are my replacement magnets too strong? I really don't know where to go with this now, bummed I'm not only out my motor but spent the money on the magnets and I can't get the motor to run.

try another Brand ESC, sometimes one brand ESC will work on one motor but not on another, has something to do with feed back, hope that helps, Chellie

MaxAdventure
08-14-2010, 12:34 AM
try another Brand ESC, sometimes one brand ESC will work on one motor but not on another, has something to do with feed back, hope that helps, Chellie

Thanks for the response; as a background I was running this motor very successfully with a CC Phoenix HV85 and my try after the rebuild was a CC Phoenix HV110. My biggest concern is turning the motor by hand feels different with the new magnets. Is it a sign it just won't work, or maybe I need to play with my ESC timing/khz/etc?

Larry3215
08-14-2010, 03:43 AM
Double check your magnet poles. be sure they are nsnsns and not nsnns or some other mix up.

Also - how many magnetic poles are in the motor and how many stator teeth?

Did you check before you took the old ones out to be sure yours wasnt nnssnnss?

Are the new magnets the same size as the old ones - so the spacing is the same?

Finally - did you re-wind the motor too or just replace magnets?

Check the motor for shorts - there should be NO conductivity between any of the motor windings and the shaft or stator teeth or bearing mount etc.

Last one - re-do your soldering job on all the connectors. A cold solder joint is the most common motor problem.

MaxAdventure
08-15-2010, 05:45 PM
Double check your magnet poles. be sure they are nsnsns and not nsnns or some other mix up.


I double checked on assembly, and checked again on my disassembly and they are NSNSNS


Also - how many magnetic poles are in the motor and how many stator teeth?

12 Stator teeth, 10 Magnets


Did you check before you took the old ones out to be sure yours wasnt nnssnnss?

I thought they were NSNS, however I had no idea any motor might by NNSSNNSS so I'm less confident as I was working off of NSNSNS. I seem to remember running a loose magnet around the old ones before I pulled them all and I think I would have noticed anything but NSNSNS


Are the new magnets the same size as the old ones - so the spacing is the same?

yes, had to custom order the specific dimensions and the motor has aluminum alignment teeth so it was a no-brainer on putting the new ones in.


Finally - did you re-wind the motor too or just replace magnets?

Nope, didn't touch the winds


Check the motor for shorts - there should be NO conductivity between any of the motor windings and the shaft or stator teeth or bearing mount etc.


I checked the winds for continuity, but I'm kicking myself for not thinking of checking for shorts onto the stator,etc. However going back, no shorts found between any metal parts and the winds.


Last one - re-do your soldering job on all the connectors. A cold solder joint is the most common motor problem.
I'll pull the insulation and re-solder the joints. As much as I want to believe I'm good enough to not do that, it's very valid! :D

CHELLIE
08-15-2010, 06:09 PM
It looks like the Magnets are special made for the Z motors, and other magnets may not work.

The magnets are especially made for the Z Series motors, and are rounded on both bell and stator sides. The result is that contact area with the bell is complete, and this has two benefits: First, heat transfer is maximized, so the magnets are much less subject to damage from overheating.
http://content.aircraftjapan.com/prod/HP-Z40-Z50-BEARING.jpg
Second, the full contact with the bell on one side, and matching curvature to the stator on the other, means that thehttp://content.aircraftjapan.com/prod/HP-TITAN-90HV-PO-M.jpg magnetic flux lines are complete and optimally shaped; this means higher efficiency, lower incidence of motor stalling, and smoother starts. The magnets themselves are produced in one of the foremost factories in the world, and are the latest type, featuring both an extremely high temperature rating and high magnetic strength. They are retained by fingers in the bell-end, and attached with a special high-temp glue. Finally, the high-speed, shielded stainless bearings in the Z50 Series are made by NMB Japan; expensive for Hyperion to install, but well worth it for smoothness and longevity.


http://www.aircraft-world.com/prod_datasheets/hp/z50/z50all.htm

MaxAdventure
08-15-2010, 09:09 PM
It looks like the Magnets are special made for the Z motors, and other magnets may not work.

The magnets are especially made for the Z Series motors, and are rounded on both bell and stator sides.


Well, I hadn't found that before and if they've always been curved magnets I was wrong when I originally found comments that the Century motors were re-branded Zpower.

The bottom line then is that it's a Century Motor, this one:
http://www.heli-world.com/detail.aspx?ID=9146

and the magnets I special ordered physically appear identical to the original, neither being curved.

Larry3215
08-16-2010, 12:39 AM
Well, Im about out of ideas.

What settings do you have on the esc for timing and PWM?

For outrunners, the Castle controllers work best on low timing and 8khz pwm or outrunner mode in some cases. Id try 8khz first.

In some cases a hard start is best as well.

CHELLIE
08-16-2010, 12:53 AM
Thanks for the response; as a background I was running this motor very successfully with a CC Phoenix HV85 and my try after the rebuild was a CC Phoenix HV110. My biggest concern is turning the motor by hand feels different with the new magnets. Is it a sign it just won't work, or maybe I need to play with my ESC timing/khz/etc?

I belive that if you put in Stronger magnets in trying to get more power from the motor, you have affected the ESC EMF to sense the magnet position and it cant commutate with the motor using strictly back EMF sensing. If everything is OK with the motor, then this is the only thing that is not letting the motor work, try your HV85 ESC to see if that will work, and if not, you will need to replace the original magnets back into the motor, If you want more power from your motor, i would look at the Scorpion 4025
motor, rather than trying to change magnets and affecting something else, Hope that helps, Chellie

http://www.scorpionsystem.com/catalog/motors/hk40/HK-4025-740-12n8p/

CHELLIE
08-16-2010, 01:24 AM
where is ron_van_sommeren when you need him :D :D :D LOL

MaxAdventure
08-16-2010, 02:18 AM
I belive that if you put in Stronger magnets in trying to get more power from the motor, you have affected the ESC EMF to sense the magnet position and it cant commutate with the motor using strictly back EMF sensing. If everything is OK with the motor, then this is the only thing that is not letting the motor work, try your HV85 ESC to see if that will work, and if not, you will need to replace the original magnets back into the motor, If you want more power from your motor, i would look at the Scorpion 4025
motor, rather than trying to change magnets and affecting something else, Hope that helps, Chellie



Well, I was trying to replace the magnets with the same, but I couldn't find datum on what I needed, so I gave it a best guess. I certainly didn't want to mess with something that worked (and worked well), I just needed to replace the cracked magnet. Not sure if they were identical, I replaced them all to at least be balanced.

I'm still waiting on the HV85 to come back from Castle - they have a delay due to a shortage on that particular controller. I'll start just messing around with it and let you guys know how it goes. thanks again!

CHELLIE
08-16-2010, 02:25 AM
Well, I was trying to replace the magnets with the same, but I couldn't find datum on what I needed, so I gave it a best guess. I certainly didn't want to mess with something that worked (and worked well), I just needed to replace the cracked magnet. Not sure if they were identical, I replaced them all to at least be balanced.

I'm still waiting on the HV85 to come back from Castle - they have a delay due to a shortage on that particular controller. I'll start just messing around with it and let you guys know how it goes. thanks again!

I can relate to that :D look for another used century 650 motor for parts, I found one but it was sold recently, e bay is a good source. Take care, Chellie

Larry3215
08-16-2010, 05:25 AM
Having magnets with a different strength would change the kV of the motor but would not prevent it from working.

There is something else going on i think.

MaxAdventure
09-19-2010, 04:49 PM
Well, Im about out of ideas.

What settings do you have on the esc for timing and PWM?

For outrunners, the Castle controllers work best on low timing and 8khz pwm or outrunner mode in some cases. Id try 8khz first.

In some cases a hard start is best as well.


I finally got around to trying a lot of these settings. I was using the HV110 (although I did get the HV85 back). I tried running through high timing, low timing, hard start, different khz combos, starting with what you suggested Larry, it always did the same jerking but not starting. It would heat the motor leads, usually pulled around 30A depending on the start-up settings. I kept going back looking for winding to case shorts, never found any. My current guess is there's winding to winding shorts that throws off the timing for the ESC - I really don't know what to do, but it sucks I'm out this motor. I guess I could rewind it, but I'm not currently motivated to do my first re-wind on this.

I could get another 650A motor, or a nice Scorpion, try a neu.... *shrug* I've already spent way too much on helis, what a freakin' money pit. I guess I'll cut some foam cores for my new EDF wing idea and mull over the heli....