axial design/build

The bearing and shaft that I'm liking is here; https://www.surpluscenter.com/item.asp?item=1-3696&catname=powerTrans

The high-temp(!) magnets I'll be using are here; http://www.kjmagnetics.com/proddetail.asp?prod=BX088SH
I'll order 10 at a time and I'll need at least 20.

The stator material, not counting 9 copper coils (duh), is up in the air. I'm figuring the stator will be about 6" x 6" x 5/8" when complete. Steel and other bits I'll probably source local.

Do I need halls? And anything you think I'm missing or not worrying enough about, let me know. More later. :)
 
This isn't to scale or anything but I think it shows the basics..
basic.jpg

The steel disc on the left will attach to the short flatted shaft and have 4 bolt holes near the center, tapped if I can. The disc on the right will be missing most of its center to reduce weight but it'll still have to bolt to the first disc.

The bearing will be held to the motor frame like handlebars are held in. A 4-bolt style clamp will allow me to drill a small hole on the inside of the clamp. That small hole will get filled w/ epoxy right before I set the bearing in, and the excess epoxy should fill those slots in the bearing case.

Looking and sounding ok so far? What about the slight angling of the magnets (rotor.pdf).?? It all seems legit in my head, anyway. :lol:
 
Hole in the center of the stator. A fairly large hole I guess but the coils need to fit too. :wink:

oh!...sorry, I forgot to mention the "stator.pdf" file is only a scale-able 9 piece pie and not a representation of a stator or a plan for one. :oops: But 9 coils means each coil can occupy, at most, 1 piece of the pie..the actual size and placement of the coils is left to the chef. :)
 
nameyourself said:
Stator materials is where I'll definitely need help. What's gonna withstand up to 300° (F)? :twisted:
Click to expand...
Did you see my threat on building a triple stator axial flux motor ? I use acrylic glass for the stator, Wikipedia gives its melting temperature as 320 F. I had solder blobs fall on it and a naked flame on it for a short time, this didn't affect the material...
 
Actually your builds are what inspired me to want to try one. :D

Acrylic is the backup plan, for now. I kind of want more head room though since the mags can take up to 300° F. Pliable comes before "melting", right? :)
 
That's a lot of magnet cost for something that might not work too well for the first iteration. I would suggest going with round magnets, something around 1 inch diameter and 1/8 inch thickness to start. These would be much cheaper for a first design, after which you can order the large block magnets after you have learned from your first motor.

For the stator, I tried to take design cues from the launchpoint motor, basically you want to pack your stator with copper, which means the copper will have to provide most of its own strength. The stator can be made stiffer by filling in the gaps with a high temperature epoxy or something like that. Maybe take a look at JB weld.

Finally, for your overall design, maybe look into simplifying the design, making it more compact, and trying to keep everything as stiff as possible. You probably don't want to hang the rotor off the end of the shaft like that. Maybe look at sourcing your own shaft from mcmaster and bearings from bigbearingstore instead of limiting yourself to that preassembled thing from surpluscenter.

You might want to take a look at the drawings I've posted in my own axial flux thread:
http://endless-sphere.com/forums/viewtopic.php?f=30&t=41776#p714537
http://endless-sphere.com/forums/viewtopic.php?f=30&t=41776#p714656

I'm not saying my design is best, but I have spent a long time thinking about these machines and the best way to construct them...
 
thepronghorn said:
That's a lot of magnet cost for something that might not work too well for the first iteration. I would suggest going with round magnets, something around 1 inch diameter and 1/8 inch thickness to start. These would be much cheaper for a first design, after which you can order the large block magnets after you have learned from your first motor.

For the stator, I tried to take design cues from the launchpoint motor, basically you want to pack your stator with copper, which means the copper will have to provide most of its own strength. The stator can be made stiffer by filling in the gaps with a high temperature epoxy or something like that. Maybe take a look at JB weld.

Finally, for your overall design, maybe look into simplifying the design, making it more compact, and trying to keep everything as stiff as possible. You probably don't want to hang the rotor off the end of the shaft like that. Maybe look at sourcing your own shaft from mcmaster and bearings from bigbearingstore instead of limiting yourself to that preassembled thing from surpluscenter.

You might want to take a look at the drawings I've posted in my own axial flux thread:
http://endless-sphere.com/forums/viewtopic.php?f=30&t=41776#p714537
http://endless-sphere.com/forums/viewtopic.php?f=30&t=41776#p714656

I'm not saying my design is best, but I have spent a long time thinking about these machines and the best way to construct them...
Click to expand...

I'm not too worried about magnet cost but I want good value for my money and a high temperature rating. I looked at round magnets and they seem slightly more expensive than a similarly sized block magnet and high-temp rounds would cost that much more if you can find them. I'm not considering 1/8" thick mags. I've followed a lot of axial builds and I've built some decent sized motors before. :)

As far as the stator goes, I was more interested in materials and their temp-ratings and use-techniques. Acrylic seems like it might be the easiest to build a stator plate with so I'll likely start there. That would make swappable stators somewhat cheaper and I could try different turn counts, number of coils and even different stator thicknesses.

I think the bearing from surpluscenter looks really good but I'll have to order it and see. It's a larger diameter and looks fairly wide so it should be fine...
The basic drawing doesn't show it, but the left most disc doesn't have to be on the same plane as the short-shaft. The easy-to-build version likely could be built as it is in the drawing, but the crafted version isn't shown yet. I'll try redrawing the rotor slightly larger so I can see how it looks in a couple different sizes. I typed 6"x6" for the dimensions of my circle and got almost 5", which is partly why my drawings suck so bad.

A professional could likely make a 3D model of it in 10mins..and those crappy drawings took me hours. :lol: I'll check out your threads for sure. :)
 
I drew the basic view on paper and an 8" rotor diameter would give me a lot more clearance around things. With a larger rotor diameter and a craftier clamp and frame design the entire motor including shaft could be made around 4-3/4" wide. :shock:

The bearing and shaft is drawn to scale as best I could based on it's description. Here's a quick sketch, vertical lines are 7" long..

..extending the vertical lines 2 boxes in each direction would make it 8". Sorry about the crappy photo too. :oops:

If you're not following it's ok...
I'm gonna cut out some paper magnets and an 8" diameter circle and see what kind of magnet layout I like. Tired of stupid software for now. :lol: Maybe 12 magnets per disc would work out better since there'll be more room. I just ordered the bearing and I'll see about ordering half the magnets in the next couple days. :)
 
http://en.wikipedia.org/wiki/Poly(p-phenylene_sulfide)

"Maximum service temperature is 218 °C (424 °F)"

Or Zytel or Acetal...
 
h0tr0d said:
http://en.wikipedia.org/wiki/Poly(p-phenylene_sulfide)

"Maximum service temperature is 218 °C (424 °F)"

Or Zytel or Acetal...
Click to expand...

Interesting but I'm definitely starting w/ acrylic since it's easy to find, relatively inexpensive and seems like it'd be easy to work with.
 
They shipped the bearing Tuesday so hopefully it'll show up in the next couple days. This weekend I'm gonna try to get the steel and some supplies so I can start building the frame and rotor. :)
 
The bearing showed today and it's plenty big enough. :mrgreen: Hopefully I can get some steel tomorrow and have a decent start by the end of the weekend. :)
 
Coreless, yep. And I binned the idea of doing a smaller one first. Nice, right? :lol:

Now I'm shooting for a 9" dia rotor w/ a lot more magnets. I've got it drawn for..eek..32 per side, but I'm still open to suggestions for the final magnet count and layout. In order to save money I'll switch from the linked high-temp magnets to the N52 version. I should get the steel to start the rotor on Monday.

The bearing's long shaft will take a live-axle 3/4" to 4on4 adapter so I can mount a wheel. The bearing will be clamped into a custom made single-tube swing arm (Ducati-like, built by a redneck/hick). The rotor will attach to the short shaft which obviously spins the wheel. The stator will have a hole in the center so it can be sandwiched between the rotor plates and it'll have 3 mounting holes near the outer edge so it can bolt to the swing arm.

Being able to drive it as a motor is back-burner for right now. It's gonna take more than a minute to get to the coil winding point. I haven't even put the wheel on a diet yet, so there's that to look forward to in the short term. :)

edited to add 9x32.pdf for reference. expert opinions?
View attachment 9x32.pdf
 
I guess they didn't want to cut a 1' x 2' piece of steel, so I can't start on the magnet plates. The person I talked to on Saturday made it sound like I just needed to have someone come back on Monday to get a piece cut because the guy that does the cutting wasn't there. I knew I should've hung out for a minute and walked around, I just didn't want to make the driver wait that long since we'd done other errands already. The person that was supposed to pick up the steel this morning kind of tried to eye a substitute but he saw gears from some large industrial motor and thought those could work...no..

Looks like I have to wait a week before I can get some steel plate but I can try to order the 3/4" to 4on4 adapter tonight. :)

edit...I found some tubing for the swing arm and bearing clamp and got those rough-cut. I also found at least one of the front wheels and a few other miscellaneous pieces. Cleaning/organizing is kind of relaxing for me but building and driving is definitely more exciting. :D
 
It looks like the rotor can be 11" diameter before clearance starts getting scary. Given that, I'll look at larger magnets and see what jumps out at me.

I still have a lot to do in order to make the trike roll but it should go together pretty quickly next month. Once it's together I'll have a better idea of what it's going to take to move it anyway. :)

edit..so I drew up a 10" rotor with 16 slots for 1.5" x 0.75" magnets and it might be the last one. Hopefully I can get out and get some steel plate this weekend and get that stupid adapter ordered soon.
 
seems there's no reason for me to try and build a motor..oh well. I might post a build thread in the general ebike section at some point but it'll probably be a mid-drive hub. sorry :oops:
 
I like your idea of building the motor yourself. Unfortunately I´m not good at electric devices so I will follow this thread with interest and hope to learn.
I do know something about mechanical things however and I would not recommend to anyone to clamp a bearing. There are several reasons for that most affect positioning and stress on the bearing. I don´t know your type of bearing maybe you can explain how it looks in the inside?
 
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