Brushless motors in the lego world - general topic

[janssnet]

Sorry bout that! You are absolutely right, inner diameter is 5mm.

[vergogneless]

7 hours ago, janssnet said:

Sorry bout that! You are absolutely right, inner diameter is 5mm.

Np 

 

I wanted to share a motor discovery—I'm not sure if it’s been mentioned before, but since I got to test it today, I thought I’d pass along the info!

E-Sky 2615 3500kv

• 26mm diameter
• 15mm long
• Works with 2S and 3S
• Motor shaft diameter is 3.17mm and 13mm long
• Mounting spacing perfectly adapted to the Lego system with M3 screws

It does, however, come with uncommon 2.5mm connectors, so I swapped them for 3.5mm banana plugs that are compatible with our ESCs.

I find it especially interesting because it’s much more compact than our usual A2212, and in my initial indoor tests, it’s really powerful. I didn’t feel any difference with my smaller models compared to the A2212 in a 1/3 ratio. It behaves the same way, even at very low RPMs.

Another advantage is that, with its smaller dimensions, it’s easier to fit into a space surrounded by Lego parts since you can run axles all around it without any contact—something that’s impossible with the bulkier A2212.

 

 

 

[FriedlS]

Oh very interesting. Thank you for sharing this motor, 🙂

 

[Aurorasaurus]

Well, I'm officially part of the club! My A2212 and geekservo finally arrived, and I have a fully working motor setup. I just have one problem. My geekservo wont turn full 180 turns, and the dial on my transmitter that controls its maximum is set to the highest amount of movement. Im using a dumborc x6 and x6fg, quicrun 16BL30 esc, and 1500mah 3s lipo that's charged correctly atm. I think I calibrated the transmitter correctly, but maybe I need to calibrate the receiver somehow too. Any tips?

Edit: I should also say, I've tried toggling the gyro on the receiver. My specific receiver model is the x6fg v1.1, which seems to have no official information available online...

Edit #2: I pushed the button on the receiver 4x and now its fine, apparently. Sorry for the fuss.

Edited November 12, 2024 by Aurorasaurus
add extra info

[Krxlion]

5 hours ago, Aurorasaurus said:

Well, I'm officially part of the club! My A2212 and geekservo finally arrived, and I have a fully working motor setup. I just have one problem. My geekservo wont turn full 180 turns, and the dial on my transmitter that controls its maximum is set to the highest amount of movement. Im using a dumborc x6 and x6fg, quicrun 16BL30 esc, and 1500mah 3s lipo that's charged correctly atm. I think I calibrated the transmitter correctly, but maybe I need to calibrate the receiver somehow too. Any tips?

Edit: I should also say, I've tried toggling the gyro on the receiver. My specific receiver model is the x6fg v1.1, which seems to have no official information available online...

Edit #2: I pushed the button on the receiver 4x and now its fine, apparently. Sorry for the fuss.

I've been there. If you turn on gyro function on DumboRC receiver it will shorten the movement of servo, simply to still have some "room" for counter-steering. :)

[Aurorasaurus]

I've now done a bit of playing with my new brushless toys, and run into the same problem as everyone else: wheel hubs.

I have a 3d printer and some small bearings that fit axles through, and I think I want to have metal U joints come out of the hubs. Currently I'm thinking 5.5m axle through the bearing so it cant slide out, then use pinholes to get ball joint pieces in the right places. What does everyone else think? what should I focus on?

Metal parts initially seem like an acceptable option, but the price is too much, even if I had any money at the moment...

[Aurorasaurus]

I've been working on using an A2212 motor and the planetary reduction from a fake PF XL motor. I think the reduction is around 1:37.

The idea is simple, use a 3d printed adapter to connect the xl motor housing to the brushless motor. I also made a simple shaft adjustment guide. You screw the motor onto the guide piece, then loosen the screw holding the motor shaft, and press the shaft down in a vice until the shaft is at the length set by the guide piece. Then you can press the 12 tooth .5 module gear that is required to use the xl motors reduction onto the shaft, and it will all be spaced correctly. This all worked fine for me, and the STL files are on bricksafe if anyone else wants to try. https://bricksafe.com/pages/Aurorasaurus/brushless/problems

All that is fine, but I have a problem. I think the motor I bought to use with the xl motors reduction was bad, and fried my ESC (links in spoiler)

Spoiler

https://www.rcnz.com/categories/electric-motors-and-accessories/brushless-motors/aircraft-brushless-motors/rcnz-22-12-brushless-outrunner-motor-2700kv/
https://hobbystation.co.nz/hobbywing-quicrun-16bl30-esc-2s-3s/

The motor was like this when I got it, and you can sometimes feel some rubbing as you turn it manually.

I think it broke the ESC, because now when I turn the system on, the light on the ESC flashes red quickly. If I hold down the button on the ESC switch thingie it blinks less quickly but nothing different happens.

Videos of the motor working and then not, and the ESC: https://bricksafe.com/files/Aurorasaurus/brushless/problems/20241122_123656.mp4 https://bricksafe.com/files/Aurorasaurus/brushless/problems/20241122_123906~3.mp4

What should I do?

[Krxlion]

9 hours ago, Aurorasaurus said:

I've been working on using an A2212 motor and the planetary reduction from a fake PF XL motor. I think the reduction is around 1:37.

The idea is simple, use a 3d printed adapter to connect the xl motor housing to the brushless motor. I also made a simple shaft adjustment guide. You screw the motor onto the guide piece, then loosen the screw holding the motor shaft, and press the shaft down in a vice until the shaft is at the length set by the guide piece. Then you can press the 12 tooth .5 module gear that is required to use the xl motors reduction onto the shaft, and it will all be spaced correctly. This all worked fine for me, and the STL files are on bricksafe if anyone else wants to try. https://bricksafe.com/pages/Aurorasaurus/brushless/problems

All that is fine, but I have a problem. I think the motor I bought to use with the xl motors reduction was bad, and fried my ESC (links in spoiler)

  Reveal hidden contents

https://www.rcnz.com/categories/electric-motors-and-accessories/brushless-motors/aircraft-brushless-motors/rcnz-22-12-brushless-outrunner-motor-2700kv/
https://hobbystation.co.nz/hobbywing-quicrun-16bl30-esc-2s-3s/

The motor was like this when I got it, and you can sometimes feel some rubbing as you turn it manually.

I think it broke the ESC, because now when I turn the system on, the light on the ESC flashes red quickly. If I hold down the button on the ESC switch thingie it blinks less quickly but nothing different happens.

Videos of the motor working and then not, and the ESC: https://bricksafe.com/files/Aurorasaurus/brushless/problems/20241122_123656.mp4 https://bricksafe.com/files/Aurorasaurus/brushless/problems/20241122_123906~3.mp4

What should I do?

If you fell rubbing, maybe the screws are too long, and they are touching the winding or the case of the motor. Also, the cable management of the motor can be bad and it is touching the rotating case. It's hard to tell to be honest.

I feel like 1:36 reduction (two stages of planetary reduction) may be too much. With 1000kv motor, you will have around 300RPM at max throttle. You may consider having higher KV A2212 motor. Anyway, good luck with your project :)

[Aurorasaurus]

7 minutes ago, Krxlion said:

I feel like 1:36 reduction (two stages of planetary reduction) may be too much. With 1000kv motor, you will have around 300RPM at max throttle. You may consider having higher KV A2212 motor. Anyway, good luck with your project :)

Ah, I forgot to mention - that motor was 2700kv :)

The screws arent too long, i can see them just poking through a tiny bit, not enough to be a problem. I think it's just a faulty motor, so the seller is sending a replacement, which is kind of them. Too bad it fried my ESC though...

I've also been working on wheel hubs with bearings, but I applied too much glue and didnt press them hard enough before the glue set, so they dont rotate perfectly smoothly and arent balanced. I can show some photos tomorrow if there is any interest.

[gyenesvi]

I have been discussing this with @Aurorasaurus during the design of this motor, and I find this one of the best possibilities for using the A2212 motor so far. With a 2700 kv motor at 12V you get 900 RPM, which is a good range for a heavier offroad model meant for climbing instead of being fast, and probably has plenty of torque. Obtaining the critical part, the planetary reduction, and marrying it with the motor itself is fairly simple. Also, I think the housing itself can be further improved by having the front part also custom printed with better mounting points, more pinholes, more like on a PU XL motor. Then the two halves could be joined together with screws instead of relying on clips, like some other designs presented in this thread before.

I wonder about the difference between an 1000kv and a 2700kv 2212 motor, besides the speed. I guess the size is the same, so is it like the 1000kv has that much more torque, or is it that it consumers that much less power? I guess the slower speed has to be compensated somewhere, right?

[Aurorasaurus]

5 hours ago, gyenesvi said:

I wonder about the difference between an 1000kv and a 2700kv 2212 motor, besides the speed. I guess the size is the same, so is it like the 1000kv has that much more torque, or is it that it consumers that much less power? I guess the slower speed has to be compensated somewhere, right? 

I was wondering about this too. The page i got the motor from said it was 240w. I'm not sure how that compares to others' 1000kv motors though. It was also 5 turns, while the 1400kv motor I have is 10 turns.

 

6 hours ago, gyenesvi said:

Also, I think the housing itself can be further improved by having the front part also custom printed with better mounting points, more pinholes, more like on a PU XL motor. Then the two halves could be joined together with screws instead of relying on clips, like some other designs presented in this thread before. 

Sure, I guess I know what I'm working on next :)

[Variteck]

Hello everyone, I am very happy to participate in this discussion group. I want to present my solution to make this 1.5 kg Trophy Truck run at high speed.

https://bricksafe.com/pages/Variteck/trophy-truck-panoramica-

It all starts with an 12-tooth Lego gear hooked up to a 3200kv brushless motor, powered by a 3S 11.1v LiPo battery, through a 45A ESC. The gear and motor are connected by inserting a plastic card into a 2L axle connector, and held together tightly by a metal drill depth stop ring.

The mechanism allows a 17,5x speed reduction, including the 3x reduction provided by the Portal axle.

https://bricksafe.com/pages/Variteck/2l-axle-connector

The real challenge in taming the rotation speed generated by the brushless motor was to avoid melting the technic parts. In the first attempts, the primary and secondary axle support parts were guaranteed to melt or break.

https://bricksafe.com/pages/Variteck/broken-parts

The technic holes couldn't hold: holes within holes were needed. I then made a sort of linear bearing so that the axles did not spin directly in the technic holes, but instead inside pin connectors that in turn spin in 1x2 stud housings: cages with four walls capable of hosting 2L pin connectors or Liftarm Thick 1x1 plus Technic Bush 1/2 , depending on the case. In this way the friction is shared between the housing and the connector. The backlash between the rotation axes is really minimal and does not affect the final result.

https://bricksafe.com/pages/Variteck/hole-in-hole-technique

From the first road tests there is no evidence of melting of the plastic and no fractures, and the Trophy Truck can reach great speed: I am not able to measure it at the moment but from experience I can say that it is much higher than the previous version of the rear axle, originally composed of two buggy motors powered by 2 Buwizz. This is despite the fact that I conducted my tests with the ESC's maximum power setting set to 75%.

Considering the nominal power of the motor, delivering all 11.1 volts of the 3S LiPo battery we start with 35,520 rpm, which become 2029 rpm after the 17,5-fold reduction: about 33 revolutions per second.

[Aurorasaurus]

7 hours ago, Variteck said:

https://bricksafe.com/pages/Variteck/trophy-truck-panoramica-

It looks like a solid build. Have you got any footage of it?

[Variteck]

3 hours ago, Aurorasaurus said:

It looks like a solid build. Have you got any footage of it?

It is my modification of the original Goober Reboot trophy truck. Here is the link to his presentation video:

 

I made it two studs wider, made some minor modifications and above all redesigned the rear axle to accommodate the brushless motor.

Edited December 15, 2024 by Variteck

[Lixander]

14 hours ago, Variteck said:

Hello everyone, I am very happy to participate in this discussion group. I want to present my solution to make this 1.5 kg Trophy Truck run at high speed.

https://bricksafe.com/pages/Variteck/trophy-truck-panoramica-

It all starts with an 12-tooth Lego gear hooked up to a 3200kv brushless motor, powered by a 3S 11.1v LiPo battery, through a 45A ESC. The gear and motor are connected by inserting a plastic card into a 2L axle connector, and held together tightly by a metal drill depth stop ring.

The mechanism allows a 17,5x speed reduction, including the 3x reduction provided by the Portal axle.

https://bricksafe.com/pages/Variteck/2l-axle-connector

The real challenge in taming the rotation speed generated by the brushless motor was to avoid melting the technic parts. In the first attempts, the primary and secondary axle support parts were guaranteed to melt or break.

https://bricksafe.com/pages/Variteck/broken-parts

The technic holes couldn't hold: holes within holes were needed. I then made a sort of linear bearing so that the axles did not spin directly in the technic holes, but instead inside pin connectors that in turn spin in 1x2 stud housings: cages with four walls capable of hosting 2L pin connectors or Liftarm Thick 1x1 plus Technic Bush 1/2 , depending on the case. In this way the friction is shared between the housing and the connector. The backlash between the rotation axes is really minimal and does not affect the final result.

https://bricksafe.com/pages/Variteck/hole-in-hole-technique

From the first road tests there is no evidence of melting of the plastic and no fractures, and the Trophy Truck can reach great speed: I am not able to measure it at the moment but from experience I can say that it is much higher than the previous version of the rear axle, originally composed of two buggy motors powered by 2 Buwizz. This is despite the fact that I conducted my tests with the ESC's maximum power setting set to 75%.

Considering the nominal power of the motor, delivering all 11.1 volts of the 3S LiPo battery we start with 35,520 rpm, which become 2029 rpm after the 17,5-fold reduction: about 33 revolutions per second.

Very interesting. I was also working on a brushless mode on the same trophy truck, but I stopped due to the fact that I used the new CV joints, which I found by myself that simply can`t take the speed and torque of a brushless set-up :/

Moreover, nice to see someone who managed to get such a high gear ratio using Lego gears without having tens of gear sets.

Also, what motor size do you use? I wanted to fit a 3300KV 3650 sized motor.

P.S. - an advice: the 1 mod 12t RC pinion fits the Lego gears perfectly.

Edited December 15, 2024 by Lixander

[Variteck]

1 hour ago, Lixander said:

Very interesting. I was also working on a brushless mode on the same trophy truck, but I stopped due to the fact that I used the new CV joints, which I found by myself that simply can`t take the speed and torque of a brushless set-up :/

Moreover, nice to see someone who managed to get such a high gear ratio using Lego gears without having tens of gear sets.

Also, what motor size do you use? I wanted to fit a 3300KV 3650 sized motor.

P.S. - an advice: the 1 mod 12t RC pinion fits the Lego gears perfectly.

Dimensions: 2838.

Can you explain your advice to me?

[Lixander]

25 minutes ago, Variteck said:

Dimensions: 2838.

Oke.

25 minutes ago, Variteck said:

Can you explain your advice to me?

Sure: I was saying that instead of the 12t Lego gear and the contraption with the plastic card, you can use a 12t mod 1 pinion gear from a hobby-shop near you.

It might be hard to find such a pinion gear with a 3.17mm motor shaft hole, but you can easily get a shaft adaptor.

I use one of these pinion with 5mm shaft hole, but I got a 5mm to 3.17mm shaft adapter.

Edited December 15, 2024 by Lixander

[Variteck]

1 hour ago, Lixander said:

Oke.

Sure: I was saying that instead of the 12t Lego gear and the contraption with the plastic card, you can use a 12t mod 1 pinion gear from a hobby-shop near you.

It might be hard to find such a pinion gear with a 3.17mm motor shaft hole, but you can easily get a shaft adaptor.

I use one of these pinion with 5mm shaft hole, but I got a 5mm to 3.17mm shaft adapter.

Thank you.

I had thought about considering RC gears, but knowing the power of this beast of a motor I preferred to avoid contact between metal teeth and plastic teeth ;) Also, even though I'm a fanatic of power and speed, I wanted to limit the use of non-Lego components as much as possible.

[Lixander]

Just now, Variteck said:

Thank you.

I had thought about considering RC gears, but knowing the power of this beast of a motor I preferred to avoid contact between metal teeth and plastic teeth ;) Also, even though I'm a fanatic of power and speed, I wanted to limit the use of non-Lego components as much as possible.

No problem.

Yeah, a metal pinion gear might damage the Lego ones :/

But anyway, I am looking forward for a video or at least for a speed measurement...........you can attach a smartwatch to the model and set it on the bike exercise mode or something similar.

[Variteck]

Hello everyone. Here are some updates regarding my brushless motor application project. After a test on an off road RC track with jumps my model suffered various damages: fracture of a rear wheel axle, front wheels ejected several times from their housings, and above all some elements of the transmission were irreparably melted, creating a Picasso of gears.

https://bricksafe.com/files/Variteck/broken-parts/IMG_20241221_212448_edit_166444152809690.jpg

Luckily the carbon fiber axle came out incredibly intact, and was able to be extracted.

https://bricksafe.com/files/Variteck/broken-parts/IMG_20241223_212931.jpg

I subsequently intervened with some adjustments: in particular I applied part 92907 (Axle and Pin Connector Perpendicular Split) to both ends of the second transmission axle, and I added a metal washer with a 5mm hole next to the 20-tooth gear (after having thinned it slightly with sandpaper).

https://bricksafe.com/files/Variteck/hole-in-hole-technique/IMG_20241229_211108.jpg/640x480.jpg

https://bricksafe.com/files/Variteck/hole-in-hole-technique/IMG_20241229_231233_edit_176602055156295.jpg

I tested the trophy truck on the road again and was very satisfied with the result: the hole-in-hole technique worked perfectly and after several minutes of driving there was no melting. The 2L pin connectors were found to be perfectly free to rotate inside their housing, and the axle free to rotate inside them. 

I measured the speed of the vehicle with my old Honor 8 and a ffp2 mask ;) The overall weight (without the bodywork, and with the phone on board) was 1430 grams: with the ESC power set to 75% I measured a maximum speed of 21 km/h. The driving environment was not optimal, I think I can achieve even better results by driving in larger spaces. 

https://bricksafe.com/files/Variteck/road-test/IMG_20241229_110155.jpg/1280x1707.jpg

I'm still working on the vehicle to get it ready to test at 100% ESC power, but so far I'm happy with it.

[vergogneless]

18 hours ago, Variteck said:

Hello everyone. Here are some updates regarding my brushless motor application project. After a test on an off road RC track with jumps my model suffered various damages: fracture of a rear wheel axle, front wheels ejected several times from their housings, and above all some elements of the transmission were irreparably melted, creating a Picasso of gears.

https://bricksafe.com/files/Variteck/broken-parts/IMG_20241221_212448_edit_166444152809690.jpg

Luckily the carbon fiber axle came out incredibly intact, and was able to be extracted.

https://bricksafe.com/files/Variteck/broken-parts/IMG_20241223_212931.jpg

I subsequently intervened with some adjustments: in particular I applied part 92907 (Axle and Pin Connector Perpendicular Split) to both ends of the second transmission axle, and I added a metal washer with a 5mm hole next to the 20-tooth gear (after having thinned it slightly with sandpaper).

https://bricksafe.com/files/Variteck/hole-in-hole-technique/IMG_20241229_211108.jpg/640x480.jpg

https://bricksafe.com/files/Variteck/hole-in-hole-technique/IMG_20241229_231233_edit_176602055156295.jpg

I tested the trophy truck on the road again and was very satisfied with the result: the hole-in-hole technique worked perfectly and after several minutes of driving there was no melting. The 2L pin connectors were found to be perfectly free to rotate inside their housing, and the axle free to rotate inside them. 

I measured the speed of the vehicle with my old Honor 8 and a ffp2 mask ;) The overall weight (without the bodywork, and with the phone on board) was 1430 grams: with the ESC power set to 75% I measured a maximum speed of 21 km/h. The driving environment was not optimal, I think I can achieve even better results by driving in larger spaces. 

https://bricksafe.com/files/Variteck/road-test/IMG_20241229_110155.jpg/1280x1707.jpg

I'm still working on the vehicle to get it ready to test at 100% ESC power, but so far I'm happy with it.

Hi! Great to see you experimenting with all of this!

To prevent losing your wheels, you can absolutely use the same part you're already using near your motor.

Be careful not to over-tighten, though, as it could create friction (especially on the rear axle). That's why you can also integrate a small flat bearing with a 5mm inner diameter. With this, you can securely tighten your wheel and also get the added benefit of a ball bearing.

Since you're working with low speeds, that should be sufficient.

You can also apply a bit of lubricant to your gears, but be careful not to "contaminate" the surrounding parts.

 

On my side, I'm mainly aiming to exceed 50 km/h, with this model even surpassing 70 km/h.

That’s why I also use quite a few metal parts, particularly metal wheel hubs with ball bearings, which allow the wheels to be tightened with screws. I also use metal differentials and gears, as well as ball bearings and connectors with screws.
But admittedly, this can get expensive. It all depends on what you're aiming for in the end!

Feel free to show us how your model evolves 

Edited December 30, 2024 by vergogneless

[Aurorasaurus]

2 hours ago, vergogneless said:

 

On my side, I'm mainly aiming to exceed 50 km/h, with this model even surpassing 70 km/h.

That's some impressive speed, would you be able to show us a video?

[Toastie]

3 hours ago, vergogneless said:

On my side, I'm mainly aiming to exceed 50 km/h, with this model even surpassing 70 km/h.

Just out of curiosity: Why are you using plastic bricks at all for this kind of speed/load? I can see the versatility of building with so many different parts available through many plastic bricks outlets ;) but doesn't that simply stress all pieces above any (plastic) limit?

Nevertheless, I love this. I am all mixing together what makes fun Not on this scale, but e.g. electronics wise or when it comes to making enclosures for electronics and so on ... Dremels are my friends

I truly enjoy seeing your progress here!

All the best,
Thorsten

[vergogneless]

19 hours ago, Aurorasaurus said:

That's some impressive speed, would you be able to show us a video?

Of course, I plan to make a video about it!

To give you more details, this setup features Zene’s motor directly connected to its metal differential, powered by a 3S battery, entirely on ball bearings, and weighing only 870g.
Zene already powers models close to 3kg at speeds between 50 and 60 km/h without even pushing them to their limits 

18 hours ago, Toastie said:

Just out of curiosity: Why are you using plastic bricks at all for this kind of speed/load? I can see the versatility of building with so many different parts available through many plastic bricks outlets ;) but doesn't that simply stress all pieces above any (plastic) limit?

Nevertheless, I love this. I am all mixing together what makes fun Not on this scale, but e.g. electronics wise or when it comes to making enclosures for electronics and so on ... Dremels are my friends

I truly enjoy seeing your progress here!

All the best,
Thorsten

Great question! What drives me to create this mix is that it combines two of my biggest passions: LEGO and RC cars.

At the level of optimization I’ve reached, plastic parts don’t suffer as much as you’d think. In fact, they’re no longer in direct contact with the load and power.
And, ultimately, even in hobby-grade RCs, plastic is still widely used!

Another advantage is that if I break something on an RC LEGO model, I can replace it easily and at a low cost. On a hobby-grade RC, replacement parts can sometimes cost a third of the car’s price, plus there are delivery delays, etc.

I’d also add that I get bored relatively quickly with a conventional RC car, which often pushes me to buy something new. It’s much cheaper for me to invest in optimizing RC LEGO models, and I also enjoy the endless creativity of building new designs without ever getting bored.

The Dremel is also a great friend of mine. Whenever I need a part that doesn’t exist, I try to create it from an existing one—or adapt certain things as needed. I even have a box full of custom LEGO pieces I’ve modified over time! :D

 

Thank you for your interest 

[Aurorasaurus]

I'd like to share a little something I've made on the weekend: A brushless trophy truck (chassis)

Sorry about the black bars on the video, the google photos tool for adding videos together is very primitive and I didnt feel like turning my computer on and using DaVinci for a 30second clip I forgot to record in 1080p.

This setup is: 1400kv 2212, hobbywing 10bl60 esc, dumborc x6fg, geekservo, 1500mah 3s lipo, metal differential from zene.

This truck wont last much longer, it has a tendency to roll because of where I placed the esc and because it's quite narrow. The next one may also be AWD, but we'll see.

Thanks for your time, and have a lovely day :)