APL's DIY axial-flux motor

Thanks larsb, certainly more work than I had thought, but mostly because it's the first,.. if I were to do it again,
things would go smoother. Defiantly learning a lot with this build.

So many little mistakes, in the end they all add up,.. I'll be lucky if it doesn't shake itself to death! One big problem
I'm having is that if I take a part out of the lathe, and then put it back in, it's not exactly in the same place as it was.
This little lathe is falling a tad short for something like this, but a lot of it is just me.

Still working on rotors and rings, lots of machining, but almost done. Can't really finish them until the bearing caps
and rotor spacers are done, since they all go together.

Think I might have figured out a way to turn it into a spoked hub motor though, by machining a flange on each bearing
cap, and drilling spoke holes in them, it would be like the Bionx D. Hmm,.. possibly. Might have to skinny it up a bit.
 
Finally got enough machining done to do a test fit, and see where I'm at with things. Definitely wider than I
wanted. It's about 2-1/4" wide now, and I see lots of things I could do to make it thinner. But for now, I'm just
going to continue to finish it up, and give it some juice. :bolt: :bolt: :bolt:

View attachment 1



Up next are the bearing caps, and spacers between the rotors, which also act as a cooling fan. I should order up
some glue for the magnets, since that's coming up pretty soon.
 
Started on some spacers, I have my fingers crossed on how they will look. I decided to try a large diameter scoop
cut that will direct air onto the center of the coils, in either direction of rotation.

Spacers.jpg

Not the original plan, butI'll give it a try. I can always make more.


View attachment 1

They'll be milled down quite a bit on each side, at least 5mm,.. something I'll have to sneak up on, because it will
determine the 1 mm air gaps on each side of the cores as well.
The outsides of the spacers are flat now, but will get turned round, to match the curve of the rotors.

I was also able to put in some central vent holes, and turn a slight relief onto the outsides of the rotors.
 
Don't make the guts too inacessible. Huge stationary shorted turns remain about each end of the stator coils. Those shorts will eventually need to be jigsawed open before it works at reasonable RPM.

You could still step with it at very low rate to measure torque. Near DC, shorted turns of the plates might not entirely stop it from spinning. I would expect a shorted load and hard magnetic braking on attempt to spin fast though.
 
It won't be very hard to take this motor apart,.. it doesn't have the radial motor's dreaded 'stator suck' that makes
them such a pain in the ass to get apart. The rotors will have threaded holes for bolts around the diameter, and
I can just 'screw' the magnet array apart, and back together.

I know what your saying about the shorted turns, and it may be a problem,.. we'll just have to wait and see. I can
cut the slots, like you say, for a quick fix. Or make some new ones using your laminated plate idea. At the moment,
I'm leaning towards some composite stator plates, G10, FR4, Garolite, Micarta, etc., but I will need a good way to
secure the cores, and keep the air gaps. ( I've been giving it a lot of thought)

I feel that the voltage (40v), and the RPM that I'm using are fairly low, and the problem you are stating is usually a
high power-high voltage issue, but of course, I've been wrong before.

As Archer321 says,.. it's common to get half way through V1, and already be planning for V2.
The primary goal of this experimental build, is still just to get it to work. After that, I might do some redesigning.

One thing that has been on my mind as of late, is that on a mid drive motor, there is not really any need for so many
slots and poles as a rear hub motor.
The motor turns three times faster than a DD motor, so it only needs a third as many coils/poles to be just as smooth.
Theres a lot of wasted construction on this motor, as a mid drive.

If I should do it again, I would probably go with something very common, like a 9/12 pole count motor, and just make
everything larger.
 
Spacers are taking a lot of time, but are finally starting to come around. Tight tolerances, and just trying to find
a 'look' that I can live with, is a slow process.


Spacers.jpg

I have them set for 1mm air gaps on each side, but thats just a guess at a place to start. Doesn't seem to be a lot
of solid info. on the net on the subject, as every motor is different. So I'll just have to try it and see what happens.
I could probably get down to .5mm if I can get all the cores in line, so theres lot's of experimenting to do on that.
Depends on how much wobble I'm going to have with the stator assembly.



Once I get the spacers drilled and taped, I'll be ready to make the bearing caps,.. and then it's getting dangerously
close to being done!
Some anodizing, glue the magnets, and the final stator wiring, and I'll be staring at a test run. :shock:

I'll have to start thinking about making a test stand for it.
 
Yes, so true larsb,.. I hope it goes smoothly, but it will probably drag me through the usual briar patch of problems.
Sure hope not.

Plus, if and when it does work, I want to put it on my bike and ride it for a while this summer, to see what it can do.
After that, I'd like to tear it down and try to shorten the cores, lighten things up, and rewind it with 14awg wire.

As it sits, it comes in at just over 13lbs. I think I can loose at least 2lbs,.. but people on diets always say that. :)

So, yea, 90% done and 50% left....
 
I was hoping nobody would notice, but yea, thats where the design came from,...

I can't slip anything past you guys on the ES! :confused:

Jetsons buildings.jpg
 
A little more progress,.. getting started on the caps. Slicing off a piece of 3.5" aluminum bar, makes me glad I bought the
band saw.

View attachment 1

After some lathe work, the drive cap is ready for mounting screws. It locates off the bearing on the bottom side. A nice
thing about the cap is that it can be machined for any drive system, whether it be a freewheel, single speed, or belt drive.
Maybe add a flange and spoke it up,.. plus dial in the spacing as well.




This one will just be tapped for a threaded adapter, to power the cruiser.
 
No, I'm not exactly sure how they are going to work. Theres not a lot of room, (1/2"), for some kind of fan set up.
I don't really want anything to 'stick out' very much, it's already a tight fit for my bike.

I wanted long/wide enough spacers to transfer toque between the rotors, and this seems like a good place to start.
( as opposed to just squirrel cage slats)

I figure either way, there should be 'some' kind of air movement around the coils,.. a lot more than a standard DD
motor. But as far as getting a specific, or correct flow pattern going,.. that will take some experimentation.
I don't know that much about fan tech.

I do wonder whether air should be pulled out, or of pushed in, though.
I figure, once it gets spinning, I can use some smoke to try and see what kind of flow is going on.
 
Finished up the rotors and caps, except for the back iron mounting holes, which will need a lot of alignment,
so I'll have to wait for the magnets to get bonded first.
The two ring sides of magnets mirror each other,..one side is north, and the other south.

I have the 3M - DP420 glue, and a buddy just happened to have an applicator gun that will work, so I'm all set to
start bonding. I just have to figure out how to space them and hold them yet. 26 per side.
If I had to buy a kit,.. the glue, gun, and the tips, it would run over $70., just to glue some magnets!



The good news is I can start anodizing the rotors, caps, and spacers! My favorite part. :)
 
Thanks qwerkus, it's getting close. :thumb:

Finished up some more anodizing, but I think it took a turn for the worse. :x

Funny how things in your head look better than they turn out.
I live in Wisconsin,.. and those are 'Packer colors', but thats not what I intended! The green is a bit ugly, and the gold is
a little too much.
Oh well, it is what it is. I might change something yet.

Anodized rotors..jpg

Moving on to the magnets, I cut out a pattern from some foam board, and plan to apply some wax to it somehow, so I can
get a couple of uses out of it, without having to peel it off the rings.
I'm hopping I can space it up a few millimeters, away from the glue, as well.

Bonding cutouts..jpg
 
APL said:
Thanks qwerkus, it's getting close. :thumb:

Finished up some more anodizing, but I think it took a turn for the worse. :x

Yeah anodizing is more miss than hits. The internet is just filled with post of angry hipster who shipped in their belove fixie frame for anodizing, and got angry over the weird color result. Motorcycle guys here usually go black or transparent/polish finish - those are pretty safe options: first one "hides" all imperfection; second one matches best the natural oxidation layer of aluminium.

That beeing said, your color results are quite interesting. The problem is probably not so much the motor than the frame: you just have the wrong frame for this color :D For an instance, it would perfectly fit any of the psychedelic corratec frames from the late 90s...

11t517k.jpg
 
Ha! So true, I just have to repaint my frame to match! It reminds me of the 'dread' Chris King headsets,.. every
part a different color.
This is going to stick out like a sore thumb, I might have to get the black rattle can out... :wink:

Well, mostly wanted to show that it 'can' be done, in any color a person wants, however, it's an acquired skill, and
a little hard to control. I've been thinking more about clear anodizing, like you said,.. a bit easier to do.

I think I'm going to change the caps to orange, just to show how it's done,.. hope I don't mess that all up! :)

Won't make the motor spin any different though, colors are just silly human stuff.
 
A buddy sent me this link today,.. thought I'd pass it along. If you get time, check it out. It's all about wires and
connectors, insulation, auto, motorsport, aircraft, and has lots of videos, and other links. :thumb:

https://www.rbracing-rsr.com/wiring_ecu.html

Some of the pictures didn't show on my PC, but maybe yours is better.
 
APL said:
A buddy sent me this link today,.. thought I'd pass it along. If you get time, check it out. It's all about wires and
connectors, insulation, auto, motorsport, aircraft, and has lots of videos, and other links. :thumb:

https://www.rbracing-rsr.com/wiring_ecu.html

That's a great resource. Bookmarked.
 
Well, I was hoping to have the magnets bonded by this time, but Spring is in the air here, and I've been busy with
picking up winters mess out in the yard.

I did manage to get the foam board waxed though. I heated up some paraffin wax in a hot plate, and dipped the
board into it, and it absorbed the wax really well!
I think it will be impervious to glue now,.. but you know how that goes. We'll soon find out.

Wax & Foam board..jpg

As far as motor colors go, I found some adhesive vinyl I had from another project, and applied that to the relief to
see what it would look like. I think it toned it down quite a bit, so maybe I'll just paint that section, and call it good.

View attachment 1

I also picked up a cheap soldering pot on the Bay for about $25., and I hope it last's long enough to do all the stator
windings. If it works, it will make stripping the enamel off all the magnet wires a LOT easier. :)

Solder pot.jpg
 
I'd consider going full black on that area where you placed the vinyl. Go full "bumble bee" in the color scheme and call it the Axial-B.
 
Too much drama the last few days, seems like everything is getting in the way of this project.

I had to look up 'Ostral',.. and still don't know what it means. :oops: But it looks Spanish, so maybe a religious thing?
Reminds me of Orested though, a measurement of magnetism,.. Orested-B? :)

I'm busy sanding the surfaces of all these magnets at the moment, another tedious job,.. and they snap in half like twigs,
if you happen to fumble one.

I've been racking my brain on how to mark them north and south, so I can keep things straight while bonding. Didn't want
to line them up on a table, because they could all jump together and break.

Then I realized that if I leave them all stacked together, they are the safest, and just flip over every other one.
Only have 20 minutes, so I need to figure out the fastest way to do it.
 
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