Open Source DIY non-hub motors

[spinningmagnets]

Rather than focus on only axial or radial, I think its now reasonable to focus on two DIY designs, for ease of "back shed" construction. An axial along the lines of the Lebowski configuration, and a radial outrunner with segmented teeth, for ease of winding and mounting the coils onto the stator.

I realize there are many more details to consider, and my ideal compromise package may not match your ideal compromise package, but...

Garage (back shed) motor builds can have a "group-buy" of laser-cut laminations to reduce the price. Once the optimum size and shape of non-hub motor laminations is identified, everything else is downhill from there. I would suggest a US legal 750W continuous @36V / 21A , and...a second larger version would be wound to provide the same RPM's at 48V and more amps for the "performance" version.

 

[markz]

Garage (back shed) motor builds can have a "group-buy" of laser-cut laminations to reduce the price. Once the optimum size and shape of non-hub motor laminations is identified, everything else is downhill from there. I would suggest a US legal 750W continuous @36V / 21A , and...a second larger version would be wound to provide the same RPM's at 48V and more amps for the "performance" version.

I am totally down with getting laminations, what size are we talking about here 45mm width? or 40mm?
I think if we can copy Crystalytes laminations in the 0.35 size (or smaller if possible) we would be ahead of the game. Because are not their lam's more silent because the lam's are cut differently then the rest.

I was thinking about this today coming home. Maybe copy John in CR's HUBMONSTER laminations with its 94% efficiency.

What kind of cost are we looking at here to get a sample set done, then regular production.

 

[spinningmagnets]

For ease of building, axial / Lebowski-style is in the lead. The forum otherpower.com / fieldlines has all the resources for affordable "slice of pie" shaped magnets for this. There are many similarities between a single-stator / dual rotor DIY wind generator and an axial flux motor of the same configuration.

If you look at a common hubmotors, all of the magnets and coils are near the edge. 205mm diameter laminations seem to be the most useful (regardless of thickness). Whether the width of the stator is 28/30mm, 35mm, 40mm, 45mm, or 50mm, they use the same pole-count and diameter. Larger diameter would mean shorter spokes. Someone took two stators from the largest diameter magic Pie and slapped them together, then custom-wound them to make a very large diameter hub that was wide. Now? we can just buy a QS 273 if you want that.

It is almost impossible for the garage builder to beat the cost-effectiveness of mass-produced Chinese motors, if they have something in the size and power-level you want. This particular thread wants to address a concern that sometime in the near future, a trade war with China may mean that the common motors are unavailable. If that happens, what is the next best option? I would suggest a DC non-hub motor. I know that most neodymium magnets and copper wire are from China too, but...raw materials will remain available from various warehouses for some time after assembled hubmotors from China have suffered an interrupted supply.

I now think that a large washing machine motor is the right size, but the wrong Kv. That means that...when considering the "universal" style of motor (known to work with both AC and DC), all you have to do is rewind it. Rewinding is a PITA, but...when you consider making a complete motor from scratch? A rewinding may prove to be worth it (if wire in the right diameter is available). The shaft, bearings, housing, and rotor are already made, and power-wise, they are already the right size (if it was a large washing machine).

As far as building an axial from scratch, Lebowskis design is so thin, he also made a "dual stator, triple rotor" that looks to be the most promising for us. For heat dispersal, I would attach the rotors to the spinning shaft, and connect the rims of the stators to the aluminium shell

 

[markz]

I was thinking when building, do a huge big aluminum structure on the inside, then when thinking about axle do a custom machine axle to accept huge ass wires and perhaps some fluid lines, then build bicycle around the motor.
8) But thats not what the common man wants.

Well sitting here, it makes me wonder how much extra is the cost from China for them to wind a motor. I never wound one myself, but I know it takes time and some small fingers unlike my fat ones.

It always comes down to cost.

 

[spinningmagnets]

A few years ago, there were quite a few RC motor drives fabricated for ebikes around here. The 80-100 and 80-85 were both considered to be a good candidate, but...the factory did not provide the low Kv's that Ebikers wanted, and they needed a 100-piece order to build a custom run.

The motor section has a "stickey index" with a link to ES member thud's thread, showing how to re-wind the 80-85 to a lower KV, and to also terminate it in Wye. Bertie also showed how to add hall sensors so you could use a standard ebike controller.

I no longer fear rewinding a motor, but it would definitely take up a couple of my days off to do it right...(first one is always the hardest)

"Re-wind of a turnigy 80/100 (Now-tutorial w/Video)" (Thud, 17 pages)
https://endless-sphere.com/forums/viewtopic.php?f=30&t=20618

 

[spinningmagnets]

With 3D printing, laser-cutting, and water-jetting....we can have all the complex shapes made by a machine, and they are precisely repeatable.

Here's an axial-flux design that looks pretty easy to make, and that's even with the builder doing some CNC (3D-printing "might" make some of the CNC'd parts cheaper and easier for the average builder to get).

http://build-its-inprogress.blogspot.com/search/label/Coreless Axial Flux Motor

Pancake form, one stator and two rotors. The magnets are in a Hallbach array, which doesn't save weight (no steel backing plates, but more magnets than the common method). However, it does provide some construction materials options...depending on price, difficulty, and availability of appropriate materials for a given builder. The pic is the stator winding 3-phase, two of the phases shown finished), which will be coated in either fiberglass or carbon fiber...