13 ms·

600 Watt, 3d-printed, Halbach Array, Brushless DC Electric Motor [video]

147 points by donquichotte 9y ago

onmobiletemp 9y ago
If used for anything substantial, such as an ebike that goes fast or up slight grades, this motor would simply melt. Its really cool though. A lot of ebikers fool around with liquid cooling but ive never seen it pulled off. This guy could take advantage of the 3d printing method to add liquid cooling and besides being really cool it might allow the motor to do useful work without melting.
- jlebrech 9y ago
  looks like a good way to iterate, just disregard the melting because the real one will use metal
- alkonaut 9y ago
  It must be very application specific what kind of air cooling you get? If you have a motor enclosed on an e-bike vs. if you have it naked on some kind of aircraft with a propeller blowing on it must make a huge difference? A problem I guess with plastic is that it doesn't conduct the heat to the outside like a metal construction would, so it will always dissipate less than metal, regardless of environment? That issue is still there if you add liquid cooling - the plastic won't transfer heat to the cooling medium either. What's the state of the art in high-temperature resistant 3D-printed materials?
  - Already__Taken 9y ago
    That carbon printer would move the heat around very well.
    - dogma1138 9y ago
      Not really, like most micro particle or fiber filaments the thermoplastic resin is the weak part. Any thermoplastic extruded filament that does not require secondary treatment is going to be heat sensitive. The filaments that are not heat sensitive are either ones that require substantial heat to extrude in the first place or at then chemically treated to not be thermoplastics anymore. If you think about this way it's simple, the melting point and the thermoplastic point of the end product needs to be substantially higher than it's operating temperature this cannot be done without additional treatment or using a process other than thermal extrusion. Resins that use chemicals or light to harden are can have thermal resistance properties, metals and other materials that are extruded or bonded at very high temperatures are also resistant to relatively high operating temperatures.
      - Already__Taken 9y ago
        Makes sense, Although I was trying to infer that the carbon material would transfer the head through the object better. Which would make using a liquid cooling channel useful. As opposed to just outright higher thermal operation. But this is only evidenced from the carbon on my XPS laptop becoming untouchable in full-sun and much of the base heating evenly from the processor.
  - crwalker 9y ago
    Ultem from Stratasys (a grade of PEI) is used frequently in aerospace applications where high temperature / low flammability are required. http://www.stratasys.com/materials/fdm/~/media/83DA2BBEE7DE4A669CFEF6B1FCA118AA.ashx http://www.stratasys.com/materials/fdm/~/media/83DA2BBEE7DE4... There's always metal too.
  - onmobiletemp 9y ago
    They print titanium and ceramics ive heard. Must be expensive. I would be very interested in seeung someone print a ceramic motor, beefed up to account for poor strength of ceramics. Yes most hub motors are closed but its very common for people to drill holes in the walls of the motor to get some air cooling. Less common is actually filling the closed hub motor with oil -- ive seen blog posts where people report that if you get that to work it does wonders for cooling. But there are huge problems with it, mainly related to accounting for the expansion of the oil as it heats up. Even less common is real liquid cooling where coolant is channelled down the axle and into the stator. Doing it with plastuc would mean having some metal inserts for heat conduction to the coils.
- MrBuddyCasino 9y ago
  Some guys from Berlin demoed heat resistant printer filament at the Make Munich. After printing, you put it in the oven and then its heat resistant up to ???°C.
Animats 9y ago
That's a nice project. The author claims 80% efficiency, which is reasonably good. Most amateur motor designs are far worse. The plastic motor shell has a very smooth finish, and screw threads. What process did he use to 3D print those fine screw threads? I didn't think any available 3D printing process was good enough for that.
- donquichotte 9y ago
  I think he printed an undersized hole, drilled it to the right diameter and then used a tap to thread it.
  - Animats 9y ago
    Look at him screwing on the end bell of the motor at 222 seconds in. [1] That's a big diameter thread, and the close-ups of it show a very clean thread. You can see the marks of the 3D printing layers on the outer motor casing, but not on the thread. I suspect that thread was turned on a lathe. [1] https://youtu.be/NFvMC3l3fGY?t=222 https://youtu.be/NFvMC3l3fGY?t=222
    - Aser 9y ago
      I've printed finer threads on my cheap 3D printer, although it took a few tries to get them the right size. It's possible that he used acetone vapour to smooth out the surface of the threads.
  - viggity 9y ago
    that would be a huge tap. the motor looks to be about 4-5" wide. you'd need a $500+ tap for that, no?
    - HeyLaughingBoy 9y ago
      Probably not tapped, but single-pointed on a lathe or thread milled: https://en.wikipedia.org/wiki/Threading_(manufacturing)#Single-point_threading https://en.wikipedia.org/wiki/Threading_(manufacturing)#Sing...
nanch 9y ago
The content-vs-time density for this video is extremely high and it was a pleasure to watch all of the video. I print in PLA rather than ABS right now so the video isn't directly applicable to my life but it's nice to see somebody working on the designs. Cheers to the author!
- kelrien 9y ago
  I would recommend PETG instead of ABS next. It is easier to print, the fumes don't smell as bad and it is a very impressive material mechanically
  - Declanomous 9y ago
    Not only do ABS fumes smell bad, they can actually be quite dangerous. I believe PETG is much safer in that regard.
zecken 9y ago
Impressive on so many fronts, it's so cool what's possible nowadays with modern prototyping tech. Thanks for sharing!
lloydjatkinson 9y ago
I hate the trend that's been going on for a few years now where they try to imply that all of a given product is 3D printed. For example this motor is easily 80% metal and copper wire for the poles. The remaining 20% is the plastic case. That is the 3D printed part. Not exactly very impressive.
- smoyer 9y ago
  Having built a motor from scratch, I've learned that the hand-winding of the coils that's impressive. Mine had no torque and was terribly inefficient but there's a local motor rewinding shop where they produce real art.
- ranit 9y ago
  It is not really implied. Like, if a road bake frame is 3D-printed it is called 3D-printed bike and doesn't imply that its wheels are not aluminium and rubber.
Already__Taken 9y ago
The enclosure looks like it's leaving a lot on the table in terms of cooling channels and structure. Given the printing can do all kinds of shapes it looks like it's replicated the kind of body that would come out of a mill or mold. Are there any printers that can put down glass fibre in the process?
- jononor 9y ago
  The MarkForged 3d-printers can put down carbon or kevlar fiber with Nylon binder.
nraynaud 9y ago
We really need a cheap online laser cutting magnetic metal lamination service. There are more and more online laser cutting services, but they don't stock magnetic lamination steel. The only online specialized service is incredibly expensive. We are in a golden age of electric motors, but access to custom laminations is a limiting factor for tinkerers (now that the magnet are widely available).
- Kinnard 9y ago
  What would go into building something like this?
  - nraynaud 9y ago
    stock management, and expedition. I couldn't find the special steel distribution in less than 50 metric tons rolls from China. Need a few thickness and a few "qualities" in store.
- Declanomous 9y ago
  I think the issue is that anything involving custom magnetics is a niche area for hobbyists right now. I think most hobbyists and tinkerers prefer off-the-shelf parts to one-off motors, transformers, inductors, etc. That being said, I've already seen quite a few videos of people winding their own magnetics, so perhaps there is a market to be capitalized on.
  - nraynaud 9y ago
    no, I think the RC modeling people are quite numerous, and quite into custom motors, I think they are the ones who made the electric skateboards and scooters possible, BLDC control was only for serious business before them. Then, they started rewinding their motors. And after that they started putting them backwards (outrunners), by recycling brushed DC rotor laminations for the stator. But I really feel like the RC community is screaming for custom lamination. And with them will come the homemade electric car people, skateboards, bikes and wind turbine, all those tinkerers. Next step I guess will be the magnets, they will want custom magnets whose magnetization surface is not planar. And also custom arc circle magnets (for halbach array pancake motors).
tener 9y ago
This is very impressive, but keeps me wondering - how is this engine better than the stuff you can just go and buy in the shop? This is an honest question, I have no clue what are the benefits here (besides obvious coolness factor!).
- amelius 9y ago
  We're one step closer to a 3d-printer printing itself :)
  - darkwinx 9y ago
    It is already happened I believe. http://reprap.org/ http://reprap.org/
    - crwalker 9y ago
      I've never understood reprap's cult-like fascination with self-reproducing 3D printers. This is such an absurdly impossible goal that it's more of a category error than a current technological limitation: 3D printers are not organisms with ancestors, they are manufacturing tools. The things that CNC mills, injection molds, and 3D printers are made of are very different than the things they make.
      - Frenchgeek 9y ago
        Well, aiming for the possible isn't as much fun as the impossible. Also the results are less interesting, usually...
    - lostapathy 9y ago
      Not in the sense that parent post is alluding too. reprap printers use "vitamins" - the electronics, motors, hardware - in addition to the printed parts. Being able to print a motor would remove the need to buy motors.
      - phkahler 9y ago
mrfusion 9y ago
So in brushless motor the outside part with the magnets is the part that rotates? is that way it's brushless? You don't need to supply electrify to the part that moves? Or do I have this all wrong?
- lucaspiller 9y ago
  Exactly, here is a video that explains it: https://www.youtube.com/watch?v=bCEiOnuODac https://www.youtube.com/watch?v=bCEiOnuODac Compared to brushed-motors they can be more powerful for the same weight (which is why they are popular in the RC world), quieter, last longer, and produce less EM interference.
  - Offal_One 9y ago
    The downside being they need powerful rare earth permanent magnets to work, making their construction more expensive than induction or brushed universal motors.
- FungalRaincloud 9y ago
  In a brushless DC motor, the rotor is a magnet, and the stator is a series of electromagnets that can be powered independently, yes. But the rotor is still usually at the center. You're dead right on why it can be brushless - the bit that moves is the permanent magnet. One other important difference is that the coils need to be controlled by a computer of some sort to get the timing right to make a rotating magnetic field and keep the magnet spinning.
  - tonyarkles 9y ago
    And just for reference, at least in the hobby community, these are called in-runners and out-runners. An in-runner has the rotor on the inside and just a shaft that sticks out; an out-runner has the stator on the inside and the outer body of the motor rotates.
kaffeemitsahne 9y ago
What's the type of paper called that he puts on the motor at the 2:15 mark? Doesn't look like simple iron dust.
- jakeogh 9y ago
  https://en.wikipedia.org/wiki/Magnetic_field_viewing_film https://en.wikipedia.org/wiki/Magnetic_field_viewing_film
- lostapathy 9y ago
  Magnetic field viewing film http://a.co/5s8f0Kz http://a.co/5s8f0Kz

147 points by donquichotte 9y ago

If used for anything substantial, such as an ebike that goes fast or up slight grades, this motor would simply melt. Its really cool though. A lot of ebikers fool around with liquid cooling but ive never seen it pulled off. This guy could take advantage of the 3d printing method to add liquid cooling and besides being really cool it might allow the motor to do useful work without melting.

jlebrech 9y ago
looks like a good way to iterate, just disregard the melting because the real one will use metal
alkonaut 9y ago
It must be very application specific what kind of air cooling you get? If you have a motor enclosed on an e-bike vs. if you have it naked on some kind of aircraft with a propeller blowing on it must make a huge difference? A problem I guess with plastic is that it doesn't conduct the heat to the outside like a metal construction would, so it will always dissipate less than metal, regardless of environment? That issue is still there if you add liquid cooling - the plastic won't transfer heat to the cooling medium either. What's the state of the art in high-temperature resistant 3D-printed materials?
- Already__Taken 9y ago
  That carbon printer would move the heat around very well.
  - dogma1138 9y ago
    Not really, like most micro particle or fiber filaments the thermoplastic resin is the weak part. Any thermoplastic extruded filament that does not require secondary treatment is going to be heat sensitive. The filaments that are not heat sensitive are either ones that require substantial heat to extrude in the first place or at then chemically treated to not be thermoplastics anymore. If you think about this way it's simple, the melting point and the thermoplastic point of the end product needs to be substantially higher than it's operating temperature this cannot be done without additional treatment or using a process other than thermal extrusion. Resins that use chemicals or light to harden are can have thermal resistance properties, metals and other materials that are extruded or bonded at very high temperatures are also resistant to relatively high operating temperatures.
    - Already__Taken 9y ago
      Makes sense, Although I was trying to infer that the carbon material would transfer the head through the object better. Which would make using a liquid cooling channel useful. As opposed to just outright higher thermal operation. But this is only evidenced from the carbon on my XPS laptop becoming untouchable in full-sun and much of the base heating evenly from the processor.
- crwalker 9y ago
  Ultem from Stratasys (a grade of PEI) is used frequently in aerospace applications where high temperature / low flammability are required. http://www.stratasys.com/materials/fdm/~/media/83DA2BBEE7DE4A669CFEF6B1FCA118AA.ashx http://www.stratasys.com/materials/fdm/~/media/83DA2BBEE7DE4... There's always metal too.
- onmobiletemp 9y ago
  They print titanium and ceramics ive heard. Must be expensive. I would be very interested in seeung someone print a ceramic motor, beefed up to account for poor strength of ceramics. Yes most hub motors are closed but its very common for people to drill holes in the walls of the motor to get some air cooling. Less common is actually filling the closed hub motor with oil -- ive seen blog posts where people report that if you get that to work it does wonders for cooling. But there are huge problems with it, mainly related to accounting for the expansion of the oil as it heats up. Even less common is real liquid cooling where coolant is channelled down the axle and into the stator. Doing it with plastuc would mean having some metal inserts for heat conduction to the coils.
MrBuddyCasino 9y ago
Some guys from Berlin demoed heat resistant printer filament at the Make Munich. After printing, you put it in the oven and then its heat resistant up to ???°C.

Animats 9y ago

That's a nice project. The author claims 80% efficiency, which is reasonably good. Most amateur motor designs are far worse. The plastic motor shell has a very smooth finish, and screw threads. What process did he use to 3D print those fine screw threads? I didn't think any available 3D printing process was good enough for that.

donquichotte 9y ago
I think he printed an undersized hole, drilled it to the right diameter and then used a tap to thread it.
- Animats 9y ago
  Look at him screwing on the end bell of the motor at 222 seconds in. [1] That's a big diameter thread, and the close-ups of it show a very clean thread. You can see the marks of the 3D printing layers on the outer motor casing, but not on the thread. I suspect that thread was turned on a lathe. [1] https://youtu.be/NFvMC3l3fGY?t=222 https://youtu.be/NFvMC3l3fGY?t=222
  - Aser 9y ago
    I've printed finer threads on my cheap 3D printer, although it took a few tries to get them the right size. It's possible that he used acetone vapour to smooth out the surface of the threads.
- viggity 9y ago
  that would be a huge tap. the motor looks to be about 4-5" wide. you'd need a $500+ tap for that, no?
  - HeyLaughingBoy 9y ago
    Probably not tapped, but single-pointed on a lathe or thread milled: https://en.wikipedia.org/wiki/Threading_(manufacturing)#Single-point_threading https://en.wikipedia.org/wiki/Threading_(manufacturing)#Sing...

nanch 9y ago

The content-vs-time density for this video is extremely high and it was a pleasure to watch all of the video. I print in PLA rather than ABS right now so the video isn't directly applicable to my life but it's nice to see somebody working on the designs. Cheers to the author!

kelrien 9y ago
I would recommend PETG instead of ABS next. It is easier to print, the fumes don't smell as bad and it is a very impressive material mechanically
- Declanomous 9y ago
  Not only do ABS fumes smell bad, they can actually be quite dangerous. I believe PETG is much safer in that regard.

zecken 9y ago

Impressive on so many fronts, it's so cool what's possible nowadays with modern prototyping tech. Thanks for sharing!

lloydjatkinson 9y ago

I hate the trend that's been going on for a few years now where they try to imply that all of a given product is 3D printed. For example this motor is easily 80% metal and copper wire for the poles. The remaining 20% is the plastic case. That is the 3D printed part. Not exactly very impressive.

smoyer 9y ago
Having built a motor from scratch, I've learned that the hand-winding of the coils that's impressive. Mine had no torque and was terribly inefficient but there's a local motor rewinding shop where they produce real art.
ranit 9y ago
It is not really implied. Like, if a road bake frame is 3D-printed it is called 3D-printed bike and doesn't imply that its wheels are not aluminium and rubber.

Already__Taken 9y ago

The enclosure looks like it's leaving a lot on the table in terms of cooling channels and structure. Given the printing can do all kinds of shapes it looks like it's replicated the kind of body that would come out of a mill or mold. Are there any printers that can put down glass fibre in the process?

jononor 9y ago
The MarkForged 3d-printers can put down carbon or kevlar fiber with Nylon binder.

nraynaud 9y ago

We really need a cheap online laser cutting magnetic metal lamination service. There are more and more online laser cutting services, but they don't stock magnetic lamination steel. The only online specialized service is incredibly expensive. We are in a golden age of electric motors, but access to custom laminations is a limiting factor for tinkerers (now that the magnet are widely available).

Kinnard 9y ago
What would go into building something like this?
- nraynaud 9y ago
  stock management, and expedition. I couldn't find the special steel distribution in less than 50 metric tons rolls from China. Need a few thickness and a few "qualities" in store.
Declanomous 9y ago
I think the issue is that anything involving custom magnetics is a niche area for hobbyists right now. I think most hobbyists and tinkerers prefer off-the-shelf parts to one-off motors, transformers, inductors, etc. That being said, I've already seen quite a few videos of people winding their own magnetics, so perhaps there is a market to be capitalized on.
- nraynaud 9y ago
  no, I think the RC modeling people are quite numerous, and quite into custom motors, I think they are the ones who made the electric skateboards and scooters possible, BLDC control was only for serious business before them. Then, they started rewinding their motors. And after that they started putting them backwards (outrunners), by recycling brushed DC rotor laminations for the stator. But I really feel like the RC community is screaming for custom lamination. And with them will come the homemade electric car people, skateboards, bikes and wind turbine, all those tinkerers. Next step I guess will be the magnets, they will want custom magnets whose magnetization surface is not planar. And also custom arc circle magnets (for halbach array pancake motors).

tener 9y ago

This is very impressive, but keeps me wondering - how is this engine better than the stuff you can just go and buy in the shop? This is an honest question, I have no clue what are the benefits here (besides obvious coolness factor!).

amelius 9y ago
We're one step closer to a 3d-printer printing itself :)
- darkwinx 9y ago
  It is already happened I believe. http://reprap.org/ http://reprap.org/
  - crwalker 9y ago
    I've never understood reprap's cult-like fascination with self-reproducing 3D printers. This is such an absurdly impossible goal that it's more of a category error than a current technological limitation: 3D printers are not organisms with ancestors, they are manufacturing tools. The things that CNC mills, injection molds, and 3D printers are made of are very different than the things they make.
    - Frenchgeek 9y ago
      Well, aiming for the possible isn't as much fun as the impossible. Also the results are less interesting, usually...
  - lostapathy 9y ago
    Not in the sense that parent post is alluding too. reprap printers use "vitamins" - the electronics, motors, hardware - in addition to the printed parts. Being able to print a motor would remove the need to buy motors.
    - phkahler 9y ago

mrfusion 9y ago

So in brushless motor the outside part with the magnets is the part that rotates? is that way it's brushless? You don't need to supply electrify to the part that moves? Or do I have this all wrong?

lucaspiller 9y ago
Exactly, here is a video that explains it: https://www.youtube.com/watch?v=bCEiOnuODac https://www.youtube.com/watch?v=bCEiOnuODac Compared to brushed-motors they can be more powerful for the same weight (which is why they are popular in the RC world), quieter, last longer, and produce less EM interference.
- Offal_One 9y ago
  The downside being they need powerful rare earth permanent magnets to work, making their construction more expensive than induction or brushed universal motors.
FungalRaincloud 9y ago
In a brushless DC motor, the rotor is a magnet, and the stator is a series of electromagnets that can be powered independently, yes. But the rotor is still usually at the center. You're dead right on why it can be brushless - the bit that moves is the permanent magnet. One other important difference is that the coils need to be controlled by a computer of some sort to get the timing right to make a rotating magnetic field and keep the magnet spinning.
- tonyarkles 9y ago
  And just for reference, at least in the hobby community, these are called in-runners and out-runners. An in-runner has the rotor on the inside and just a shaft that sticks out; an out-runner has the stator on the inside and the outer body of the motor rotates.

kaffeemitsahne 9y ago

What's the type of paper called that he puts on the motor at the 2:15 mark? Doesn't look like simple iron dust.

jakeogh 9y ago
https://en.wikipedia.org/wiki/Magnetic_field_viewing_film https://en.wikipedia.org/wiki/Magnetic_field_viewing_film
lostapathy 9y ago
Magnetic field viewing film http://a.co/5s8f0Kz http://a.co/5s8f0Kz