Brushless motors in the lego world - general topic

[everybrickasculpture]

Awesome, just ordered some parts, I can't wait to test this out.  You can get the gears on amazon in case anyone is wondering.

[HorcikDesigns]

Thank you! It took me some time, because I wanted to save time doing it proper way as an assembly drawing. :D I positioned the parts and then made a screenshot that was then edited in photoshop. Doing it as assemblydrawing would be much easier. 

The reduction ratio gives 1:6 for 0.5module (40-16-8teeth )version and 1:5 for 0.6 module version (32-12-8) if I remember correctly.

 Parameters depend on the motor you choose. I run it so far with 2430 motor with 5800KV rating. Works quite noisy (maybe the teeth clearance could be tighter) but reliably. I have it in my EXP.SUV2 (for details see my IG (with short video) or Bricksafe, running on 2s LiPo). Different motors and voltages will give different results. To be honest, I am happy that it works the way I want and haven't made any measurements so far. The one I use is mostly for faster offroad and mild crawling like expedition or so. No extreme. But it also might be affected by cheap ESC I am using. 

The 0.5 module gears are quite common for mechatronic DIY projects, the 06 module are printable with 0.4mm nozzle at least I made that version because I accidentally bought and heat pressed the sprocmet on one of my motors and did not want to damage it while disassembling. 

Hope I answered all previously asked questions. 

It works with PLA, ASA will definitely handle more. 

Edited October 7, 2024 by HorcikDesigns

[2GodBDGlory]

On 10/7/2024 at 8:51 AM, Krxlion said:

I think on chinese website you will find plenty of 0.5M(module) gears, so you might order more in advance, haha. :D I couldn't find those locally, but you may, if you live in Canada. ;)
Regarding printing, I find my Bambu Lab A1 mini with 0.2 nozzle so precise that you can really achieve great results with it (the printer is not so expensive either).

Ok, yeah!

I've heard lots of good things about those A1's, but I'm too cheap, and maybe a bit too committed to more DIY-friendly printers to go for one just yet! So, the heavily modified old Ender 3 gets to keep on working! I haven't actually ever gotten it to successfully print with a nozzle smaller than 0.4, though. I wonder if there's settings I ought to look at for that sometime

[gyenesvi]

On 10/7/2024 at 6:26 AM, HorcikDesigns said:

I would like to show you my second version of adaptor for BL motors to be attached to LEGO MOCs.

That is a really neat construction, exactly what I was wishing for (except maybe having a two-stage planetary reduction instead of a single one). The 3x3 form factor is ideal for the Lego system, and it seems that fairly powerful motors already exist in this size.

A few questions:

- What is the total length, 8 studs, or just 7? I guess depends on the exact motor used?

- Are the wholes on the rear section inverse studs to accept half pins for support?

- Doesn't the single stage planetary reduction result in an output that's too fast? Did you need to apply significant reduction afterwards? (besides the planetary wheel hubs). I guess two stage reduction is out of the question with printed parts..

- How much torque does the motor have with this reduction? Maybe in comparison with an L / XL motor?

I have been looking around in your Makerworld profile, man, those live axle components look gorgeous, especially the diff lockable version. Wish lego made such things instead of all the non-reusable bionicle body parts.. there's sooo much room for improvement in this area.

[HorcikDesigns]

@gyenesvi well, when I saw 24mm motor, I knew my duty. :D The length depends on the motor and back cover you use, the reduction block should be cube (24x24x24mm) if I remember correctly. The length varies between 8 and 10 studs, for 2435 version it is 9 studs. 

Regarding the reduction, in early design phase I was looking into compound planetaty gears or harmonic drive type of gearing, but after testing I am more then happy with 1 stage reduction (1:6).

I the car I used it with 12/20 + diff + planet hubs gearing, and it is both strong and reasonably fast enough to melt some parts in the drivetrain, so I had to use ball bearings where it was possible. It damaged one CV joint (the new one). And it was jist the 2S lipo motor (or maybe hard braking). 

I have not made any measurements, but it definitely has some serious power. It might be too fast, but that could ve solved with motor with lower KV rating and better ESC. 

Glad you like my part designs. ;) 

[gyenesvi]

24 minutes ago, HorcikDesigns said:

I the car I used it with 12/20 + diff + planet hubs gearing, and it is both strong and reasonably fast enough to melt some parts in the drivetrain, so I had to use ball bearings where it was possible. It damaged one CV joint (the new one). And it was jist the 2S lipo motor (or maybe hard braking). 

I have not made any measurements, but it definitely has some serious power. It might be too fast, but that could ve solved with motor with lower KV rating and better ESC. 

Yeah, that sounds a bit too powerful/fast. A better ESC can improve low speed control, but I guess using a fast motor and not using the higher RPM range is kind of a waste. So yeah, motors with lower Kv rating would be better (I believe lego can safely take about 2000 RPM strong motor outputs, like two coupled Buggy motors, so given that and the 1:6 downgearing, about 1500 Kv would be ideal, assuming 2s LiPo at 7.4 - 8.4V), but I haven't really seen such Kv rating in this form factor..

Does anybody know something like that?

[Lixander]

New ”Skunkworks” model - Sprite EVO buggy.

The model has detachable bodywork panels with the same system as the original Sprite buggy, rear-wheel drive trough the new yellow differential, independent suspension on all arms and, of course, a SkyRC brushless set-up with a 60A ESC and a 3300 KV (around 12T) motor  gear ratio to around 6.20:1 (12-36t, 16-20t, 14-22t; I wished a bigger ratio, but this is all I could do at that moment).

Apart from the bodywork connection system, the front is also took from the original buggy, but it is adapted, as it uses thicker and longer suspension arms and also longer steering arms.

Moreover, some precaution measures had to be taken, so I used 4x metal U-joints and I will get a PTFE spray tomorrow.

But in a few days I will should start to test the model properly fitted with the 120mm hobby tires mounted on 56 d. x 34 mm rims.

P.S.: Sorry HorcikDesigns for derailing your brushless motor adapter post.

 

11 minutes ago, gyenesvi said:

Yeah, that sounds a bit too powerful/fast. A better ESC can improve low speed control, but I guess using a fast motor and not using the higher RPM range is kind of a waste. So yeah, motors with lower Kv rating would be better (I believe lego can safely take about 2000 RPM strong motor outputs, like two coupled Buggy motors, so given that and the 1:6 downgearing, about 1500 Kv would be ideal, assuming 2s LiPo at 7.4 - 8.4V), but I haven't really seen such Kv rating in this form factor..

Does anybody know something like that?

1500 KV is a little too low for almost any motor I think.......a quick search and there are mainly drone motors at that KV.

[Krxlion]

3 minutes ago, gyenesvi said:

Yeah, that sounds a bit too powerful/fast. A better ESC can improve low speed control, but I guess using a fast motor and not using the higher RPM range is kind of a waste. So yeah, motors with lower Kv rating would be better (I believe lego can safely take about 2000 RPM strong motor outputs, like two coupled Buggy motors, so given that and the 1:6 downgearing, about 1500 Kv would be ideal, assuming 2s LiPo at 7.4 - 8.4V), but I haven't really seen such Kv rating in this form factor..

Does anybody know something like that?

I am working on two brushless motor setups, but I want to have bigger picture on my work and have a wide range of test subjects to present my results. Currently, one motor setup works good but not great:
- A2212 1000kv with 6:1 planetary reduction, it gives 1850 RPM output on 3s battery, but I am sorry to say that it struggles to move G500 Mercedes (I rebuilded the Lego set to brushless setup, because it pictures the weight and feeling of 1:10 scale off-road car, which I am aiming to prepare perfect brushless setup to). The car also features some remote locking diffs, two speed gearbox, etc. The main point is to test the motor. I think that better ESC, could solve the issue, with 45:1(whole gear ratio, including planetary reduction, gearbox and wheel hubs reduction) gear ratio on low gear it still can cog(ESC struggle to find current angle of the motor) and not move the model.

This BL motor suited for Lego purposes is 6 stud long and 5 x 5 height/width - you can connect liftarms to the corners. Not gonna lie, it is not my whole idea of this motor, but I have redesigned a few things.

Below is a picture of my motor (and some pins/axle added, so you can see the versatility of mounting options). Everything holds very well, and the motor is build with two cases and one-step planetary reduction.

I also found a different motor, slightly bigger and hooked it to a different, suited ESC, which you can program, and initial results are really promising. I need to though redesign the whole 3d printed case for it. It looks like it will be 5x5x7 studs, but there will be no option to attach liftarms on the corners, like with my A2212 brushless motor. It is much more powerful, with steady control and I am trying to implement some safety features like slowing down, etc.

So regarding my approach on our topic - stay tuned. I will have much more to present in better form - a video, presenting all the details and some models in action.

[Krzychups]

Hello everyone!

Good job @HorcikDesigns! Your planetary gearbox with the brushless motor is very similar to Zene's one, although yours has bigger gear ratio which is better, but it's made from plastic. I wonder how rubust is it. As @Krxlion has noticed, these motors have low RPMs range, better are drone motors. It is not related to your planetary gearbox, but you use 8x5x3 mm ball bearings. How it works? I've found the smallest ball bearings which are R156ZZ ones (7.938 x 4.762 x 3.175 mm). Would you use them? There's also a possibility you have approximated the ball bearings size.

23 hours ago, gyenesvi said:

I have been looking around in your Makerworld profile, man, those live axle components look gorgeous, especially the diff lockable version.

Yeah, those are beautiful, I'm going to print them.

19 hours ago, Krxlion said:

Not gonna lie, it is not my whole idea of this motor, but I have redesigned a few things.

I see that you modelled it on this Russian's design like me. I'm looking forward to your project! I'm curious how have you made it.

Maybe some of you know it, I'm also working on custom planetary gearbox with a brushless drone motor (1:5,2 ratio). You can find it here. It has a metal planetary gearbox. It's quite long (10 studs) but I'm working on custom-made metal parts for this to reduce the lenght. It's more expensive and heavier, but it's robust, reliable and works smooth.

19 hours ago, Krxlion said:

I also found a different motor, slightly bigger and hooked it to a different, suited ESC, which you can program, and initial results are really promising.

Which motor is it?

Edited October 11, 2024 by Krzychups

[tseary]

@HorcikDesigns It's very cool to see this planetary gearbox realized. It was instantly recognizable to me because I was working on a similar design for a 2445 size motor some time ago!

Edited October 12, 2024 by tseary
I found the old files, here is a screencap from FreeCAD.

[Krxlion]

On 10/10/2024 at 8:13 PM, Krxlion said:

I think that better ESC, could solve the issue, with 45:1(whole gear ratio, including planetary reduction, gearbox and wheel hubs reduction) gear ratio on low gear it still can cog(ESC struggle to find current angle of the motor) and not move the model.

Oh boy, I was right with this one. I switched ESC to the new one that has programming feature and my A2212 lego'ish motor with one-stage planetary transmission can actually drive 2.5kg G500 without issues. I actually was able to slip the original wheels going uphill, instead of simply motor getting cogged again. Also, motor and ESC weren't hot during those tests, so I assume I could push the setup more.

The ESC is suited for 4mm banana plugs, but A2212 motor has 3,5mm(I can probably change those to 4mm) and I needed to improvise for my testing, but for my goal it was working just fine. I am tempted to record short video of me cruising around my yard, stay tuned.

23 hours ago, Krzychups said:

I see that you modelled it on this Russian's design like me. I'm looking forward to your project! I'm curious how have you made it.

Maybe some of you know it, I'm also working on custom planetary gearbox with a brushless drone motor (1:5,2 ratio). You can find it here. It has a metal planetary gearbox. It's quite long (10 studs) but I'm working on custom-made metal parts for this to reduce the lenght. It's more expensive and heavier, but it's robust, reliable and works smooth.

Which motor is it?

Yes, it was based on this one, the idea is brilliant for me, and I believe people don't recognize how good it is, simply because language barrier.

I didn't know about your approach, I will look into that, and it's good that we all have different ideas on connecting RC components to our models 

For now, I will keep the second motor as a secret, simply because I don't know if it will work out great, but my recent discovery about connecting A2212 to a better ESC, makes me think I didn't need that powerful motor at all. But we will see what the future brings.

[gyenesvi]

On 10/10/2024 at 8:13 PM, Krxlion said:

A2212 1000kv with 6:1 planetary reduction, it gives 1850 RPM output on 3s battery

This seems like an ideal speed range for Lego, and fits single-stage planetary reduction better, so the mechanics is simpler. Also, the casing is simple, as it does not require a back side! Unfortunately the 5x5 form factor is less great, but for large models it is still quite okay. Also, it is easy to swap out the motor for 1400 KV or 2200 KV, which could still work fine for faster models! I think this is also a direction worth pursuing, I was already trying to get my hands on one of those motors developed by the Russin guy but could not contact him. Great that others are also working on the same concept!

17 hours ago, Krxlion said:

Oh boy, I was right with this one. I switched ESC to the new one that has programming feature and my A2212 lego'ish motor with one-stage planetary transmission can actually drive 2.5kg G500 without issues. I actually was able to slip the original wheels going uphill, instead of simply motor getting cogged again. Also, motor and ESC weren't hot during those tests, so I assume I could push the setup more.

Great to know that with a good ESC it works fine, sounds promising!

[Aurorasaurus]

Recently I've been feeling cautiously curious about experimenting with hobby grade rc electronics in Lego builds, and I wanted to ask some questions just to make sure I'm not too far wrong with my understanding. From what I've read/seen other people using, a2212 seems to be the most common motor size people are using?

As for receivers/controllers, I think I saw people talking about dumborc, so would that be worth looking into as a beginner wanting to get the right thing the first time?

In terms of parts with bearings to avoid melting Lego, I have CAD and I'm not afraid to use it :D

As for the ESC, do I just need to match the current values to the expected draw from my motor + a safety factor?

I somewhat understand battery specifications, so I want to go with a 3s lipo.

I hope this is enough information for someone to steer me in the right direction, thanks for reading!

[gyenesvi]

2 minutes ago, Aurorasaurus said:

I hope this is enough information for someone to steer me in the right direction, thanks for reading!

When going into RC electronics, I think it is worth separating whether you'd like to just use RC stuff for control, or whether you also want to use non-lego motors. Because Lego and Buwizz motors can also be controlled with RC electronics, and that may be an easier start, as the hardest part is mounting the non-lego motor into lego builds.

However, there's a small catch for transitioning later to these RC motors: lego motors are brushed, and the above motors are brushless, and they require different ESCs (or very expensive high end ones capable of controlling both).

I think for transmitter/receiver Dumbo RC seems like an affordable and good enough start.

You might also want to get some GeekServos for steering/gearbox control, because they are better than Lego servos and it would be more complicated to control them anyway (would require another ESC). With RC receiver it is trivial to control them.

[Aurorasaurus]

Just now, gyenesvi said:

When going into RC electronics, I think it is worth separating whether you'd like to just use RC stuff for control, or whether you also want to use non-lego motors. Because Lego and Buwizz motors can also be controlled with RC electronics, and that may be an easier start, as the hardest part is mounting the non-lego motor into lego builds.

However, there's a small catch for transitioning later to these RC motors: lego motors are brushed, and the above motors are brushless, and they require different ESCs (or very expensive high end ones capable of controlling both).

You might also want to get some GeekServos for steering/gearbox control, because they are better than Lego servos and it would be more complicated to control them anyway (would require another ESC). With RC receiver it is trivial to control them.

I want to dive head first into rc, straight into brushless. Mounting the motors to lego seems to be a solved problem to me, I've seen enough clever designs reading this thread occasionally that I'm sure it is possible.

As for geek servos, is there a particularly good source for them or are they the same from every retailer?

Thanks for you speedy reply!

[gyenesvi]

5 minutes ago, Aurorasaurus said:

As for geek servos, is there a particularly good source for them or are they the same from every retailer?

I think they all come from the same manufacturer, everybody is just reselling them. AliExpress may be the cheapest, that's where I got mine.

[Krxlion]

11 minutes ago, gyenesvi said:

I think for transmitter/receiver Dumbo RC seems like an affordable and good enough start.

You might also want to get some GeekServos for steering/gearbox control, because they are better than Lego servos and it would be more complicated to control them anyway (would require another ESC). With RC receiver it is trivial to control them.

I wanted to switch my both Dumbo RC (transmitter and receiver) to something else - like flysky. But my desire to do so was because I thought my current equipment don't support some features. I was wrong (the problem I was facing was in ESC) and I still think this DumboRC X6FG combo is in my opinion the best option - money for value.

Going with brushed ESC is also a great option if you want to keep using Lego/Buwizz motors, but I have not enough knowledge in this matter to tell more. All I know is that PF port connectors are very sensitive in terms of receiving high Amps, and stacking multiple motors on the same connector can be a bad choice. But maybe there is a solution to that as well.

52 minutes ago, Aurorasaurus said:

As for the ESC, do I just need to match the current values to the expected draw from my motor + a safety factor?

Yes, you are right. Few more things from my side. ESC must be bidirectional (ESCs that are stated for cars have that option), because sometimes you can buy ESC, but it's suited for drones, and it will only move forwards. Safety factor should be around 20%, so if you have decided on a motor, look for its max amp value and multiply it by 120%, and you will know what minimal ESC amp value should be. I recently discovered that AM32 ESCs have smooth start option (also they can be programmed), and it helps a lot, if you are moving heavy vehicles.

As a cherry on top, here is a promised preview video of modified with brushless setup official Lego G500, enjoy.

If you have any questions, please do not hesitate to ask. :)

[Aurorasaurus]

On 4/27/2023 at 6:39 AM, Krxlion said:

Hi guys,
I just wanted to share with you the concept of using A2212 Brushless motor to drive front and back axles at the same time.

Is there any reason you didn't attach the cv joints to the motor instead of attaching axle joiners to the motor and cv joints to the axle joiners?

Was that because you originally planned to not use the planetary hub to gear down?

I'm thinking about using the same method you used and was thinking I could save 4 studs this way.

[Krxlion]

1 hour ago, Aurorasaurus said:

Is there any reason you didn't attach the cv joints to the motor instead of attaching axle joiners to the motor and cv joints to the axle joiners?

Was that because you originally planned to not use the planetary hub to gear down?

I'm thinking about using the same method you used and was thinking I could save 4 studs this way.

There is no reason at all. I was just messing with different options of reducing rpm of A2212 motor. I believe back then I used @janssnet method to insert motor shaft to lego connector (for CV joint it would work the same, and I used it that way HERE).

[vergogneless]

Hi brushless club, just dropping by to show a new method for securely attaching a Lego axle to a brushless motor shaft. I haven’t tested it under real conditions yet, but it seems promising. So far, no matter how hard I try to twist it by hand, it doesn’t budge or slip at all. When I tried the same thing with super glue and baking soda, it would give way pretty quickly.

I don’t know the name of this small piece in English, but you can find various types on AliExpress. They come in different inner diameters—I'm using a 5mm one to slide the black Lego piece in and then fit it onto the 3.17mm motor shaft.

You first need to drill the black Lego piece so that the screws can pass through and make contact with the motor shaft after tightening

My concern is that it might loosen a bit during use with the vibrations and so on. I’ll test it under real conditions once I’ve built a brand-new prototype when my large MTP order arrives. I’ll have an answer in about two weeks.

If it turns out not to be effective, I’ll most likely make the ultimate decision to bring out the TIG welder and start welding (metal axle, metal gear, etc.)

 

 

[2GodBDGlory]

Interesting solution! I can see that working well for lighter-weight models, like you've been building, but probably not for large, heavy models

[vergogneless]

1 minute ago, 2GodBDGlory said:

Interesting solution! I can see that working well for lighter-weight models, like you've been building, but probably not for large, heavy models

That’s true! But still, before bringing out the welding station, I have another idea in mind. I’m thinking of lightly grinding the motor shaft to create a VERY slight flat spot on each side, where the screws will make contact. But I’m worried I might end up slightly misaligned doing that, as it requires a certain level of precision. We’ll see!

[2GodBDGlory]

2 hours ago, vergogneless said:

That’s true! But still, before bringing out the welding station, I have another idea in mind. I’m thinking of lightly grinding the motor shaft to create a VERY slight flat spot on each side, where the screws will make contact. But I’m worried I might end up slightly misaligned doing that, as it requires a certain level of precision. We’ll see!

I've done something similar, grinding flats onto the output shafts of stepper motors, to allow for tightening 3D printer extruder gear grub screws onto them. It worked well for me there, but obviously it's a much lower-speed operation

[janssnet]

Great method, works well, also under serious load. Adjustment ring with 3mm screw. Best dimensions: 5mm inner diameter, 8mm outer diameter.

With a bit of luck the axle runs free between two LEGO motor mount links (might require some sanding of the ring to make it < 8mm).

https://drive.google.com/file/d/1CFitfryYzmyNKNo-57e2chE14JZNydfd/view?usp=sharing

 

 

 

Edited November 11, 2024 by janssnet

[vergogneless]

2 hours ago, janssnet said:

Great method, works well, also under serious load. Adjustment ring with 3mm screw. Best dimensions: 4mm inner diameter, 8 mm outer diameter.

With a bit of luck the axle runs free between two LEGO motor mount links (might require some sanding of the ring to make it < 8mm).

https://drive.google.com/file/d/1CFitfryYzmyNKNo-57e2chE14JZNydfd/view?usp=sharing

 

 

 

Thanks for sharing! But I’m not sure how you’re able to fit a Lego piece with an approximate diameter of 4.7mm so easily into a 4mm inner diameter. I tried it since I also have a 4mm inner diameter piece, and it’s impossible to fit it in, even with a lot of force—I had to sand down the Lego piece. I think you’re using a 5mm inner diameter. Also, like you, I tried creating a slight flat spot on the end of the motor shaft, but tightening the screw on it slightly misaligns the blue (or the longer black one in my case) Lego piece.

This is not ideal because it makes the gear spin off-center, even if only slightly, which causes unwanted tension at speeds of 40-50km/h, plus it creates a loud noise.

Your method remains a mystery to me, as it seems technically impossible and pretty unstable for the long term, but I’m glad it works for you—your video certainly shows that it does