Farfle joins the MENS club

[MattyCiii]

excuse my ignorance, (I did search) but what is the MENS club? (Google searches only bring up Gentlemen's Clubs )

Hmm, I cant find the thread. I shot a PM to AJ.

I looked it up myself today: viewtopic.php?f=26&t=16957

[cal3thousand]

excuse my ignorance, (I did search) but what is the MENS club? (Google searches only bring up Gentlemen's Clubs )

Hmm, I cant find the thread. I shot a PM to AJ.

I looked it up myself today: viewtopic.php?f=26&t=16957

Haha... thanks for the link. Looks like I need to figure out a mid mount for my next project.

[John in CR]

... the dual pie is pretty much cooked, may it rest in peace. I may turn the stator into a trophy for this race.

Great trophy idea. I don't mean to make light of it, but what happened? Did you try the oil and the motor objected to it being the best thing since sliced bread?

John

[Farfle]

Nothing that extreme, since I put the big tires on, it's overheatind issue got made worse, then I tried to race a turboed WRX from a stoplight, I beat him the first time,I beat him the second time too, but the motor was already really hot. And then sitting at a stoplight for a while let the heat soak, and it demagnetized the magnets, plus that stator iron has been stuffed since the moment I made it, 1kw of no load heat. Im pretty much done with it, A trophy would be a fitting resting place for it.

[Miles]

Farfle,

If you could post up the drawing of the core, we could use it as the example for the FEMM tutorial. It would be more interesting to use a real example. We only need an accurate drawing or the dimensions of a single tooth profile, airgap, magnets and rotor yoke. What do you think? I've got most of the information already, from your photos.

[John in CR]

Nothing that extreme, since I put the big tires on, it's overheatind issue got made worse, then I tried to race a turboed WRX from a stoplight, I beat him the first time,I beat him the second time too, but the motor was already really hot. And then sitting at a stoplight for a while let the heat soak, and it demagnetized the magnets, plus that stator iron has been stuffed since the moment I made it, 1kw of no load heat. Im pretty much done with it, A trophy would be a fitting resting place for it.

At least you won. That's the important part.

John

[Farfle]

Farfle,

If you could post up the drawing of the core, we could use it as the example for the FEMM tutorial. It would be more interesting to use a real example. We only need an accurate drawing or the dimensions of a single tooth profile, airgap, magnets and rotor yoke. What do you think? I've got most of the information already, from your photos.

Absolutely, ill get magnet and airgap dimensions for you. My trial of sketchup pro ran out, so I cant export dxfs anymore. Ill see if the robotics team has a spare copy of autocad.

[Miles]

Absolutely, ill get magnet and airgap dimensions for you. My trial of sketchup pro ran out, so I cant export dxfs anymore. Ill see if the robotics team has a spare copy of autocad.

If you give me the dimensions, it's only a few minutes work to do the drawing.

I think all I need for the core are:

Tooth head thickness
Inner diameter
and the radii of the fillets

[Miles]

Working from your photo, I get:

Tooth head thickness - 2mm
Inside diameter - 116mm
Fillet radii - 2.5mm & 1.5mm

[Farfle]

Ok, few more pics. You were really close with those dims. I had to get out the feeler guages to measure the flux gap, Its REALLY small, its about .3mm and the upper raidus is 3.5mm



Lower radius:

[Miles]

Great. Thanks.

Magnets 3.2mm thick?

Also, your 6.66mm for the stator yoke is up to the retaining lip. I estimated 10mm overall. Does that seem ok?
The central structure is a steel pressing? A check for the inside diameter of the core could be to take the inside diameter of the pressing and add 2x the thickness of the material that it's fabricated from?

[Farfle]

It is 6.66mm, the retaining lip has been lathed off, asks yes, mags are 3.3mms thick.

[Miles]

It is 6.66mm, the retaining lip has been lathed off,........

Thanks. I see that now

[Farfle]

The inside pressing is for all intents and purposes a solid piece of aluminum.

[Miles]

Here's the first analysis, using N32 magnets... [scale in full sized image]
I've also attached the DXF

Max. flux density at 2.17 T

[Farfle]

Here's the first analysis, using N32 magnets... [scale in full sized image]
I've also attached the DXF

Max. flux density at 2.17 T

Im looking at the picture, and im not sure what to think, is that good?

[Miles]

The magnet back-iron is well into saturation with N32 magnets and the tooth heads too. I wonder if there is any way we could find out what magnets they use? Gauss meter? You're sure the gap is as little as 0.3mm?

[Farfle]

I can measure again, but its somewhat difficult, as the iron doesn't hold still with one sidecover off, and I don't have a set of calipers big enough to measure the OD of the stator and the ID of the magnets.

[Farfle]

I remeasured it with 3 different feeler guages pressed around the edges, the flux gap is between .5mm and .6mm. I also did some winding calcs, and its good news. The original was 31 turns of 2 paralelled 18 awg and spun 420 rpm at 44v. So, if the stator is twice as wid e, but im running twice the voltage they should cancel out. So, ill rewind it with 5 turns of 12 paralelled strands of 18 awg.. Should get it spinning around 3k rpm at 100v and with a phase wire bundle thats the equivalant of almost 6 awg

[Miles]

I remeasured it with 3 different feeler guages pressed around the edges, the flux gap is between .5mm and .6mm.

That makes more sense. I'll adjust the model and re-run the analysis.

[Miles]

Doesn't make a lot of difference....

[Farfle]

Does that mean that this motor needs less magnet/ better stator iron?

[Miles]

I think all we can say at this stage is that it might benefit from a thicker back-iron for the magnets. We really need to find out the strength of the magnets though. I used N32 specification for the above. Any chance of borrowing a gauss meter?

[Farfle]

I just messaged my physics prof at the local community college, but hes not checking the mail often as its summer. I have a few other messages out, so we will see if anything turns up. In the meantime, is this motor worth working on?

[Farfle]

Would it be worth making the inner stator out of mild steel, and the can that holds the two magnet rings together also out of mild streek?