Brushless motors in the lego world - general topic

[Aurorasaurus]

1 hour ago, Krzychups said:

Good to hear. Look at my designs or at @Daniel-99 bricksafe. He has custom wheel hubs. I've modelled them on the wheel hubs he has.

Why I can't hide text and images?

Your hubs look really good, have you used them in a model? and would you consider sharing the 3d model?
Weird, I cant find the option for hiding text and images now either. @aFrInaTi0n Are you aware of this?

[Aurorasaurus]

Hello friends! It had been a while since I made a brushless model, so I whipped up a quick chassis last night and had a little play. This model is using my newest design of wheel hubs, which are the same mounting points as the standard hubs found in 42077, 42096, 42156, and literally every 1:10 car. This means I can also use them as a replacement with less resistance on non brushless models.

And a quick video of it in action:

More about the wheel hubs:

The idea with these hubs is that there is always a weak link, and its better if it is easy to repair. These hubs need no glue, and only 1 bearing. They print easily, and only break a bit if you drive the wheel into a signpost. Not that I'd ever do that, right!?

Instead of needing to buy new bearings and more glue and dealing with that mess, you just reprint it when it breaks. This also means that you can really drive the models and not worry about breaking expensive parts. Perfect for me!

Link for the STL for the front hub
Link for the STL for the back hub

 

.18mm layer height    .2mm first layer    6 walls    90% support cubic infill     PLA+ (but try other materials)     pause at layer 106, then wait some time for the plastic to shrink slightly so the bearing goes in nicer, continue the print like normal

I hope this helps someone out!

Edited February 18 by Aurorasaurus
Add link for rear hub

[Krxlion]

Great work @Aurorasaurus, maybe one day I will convince myself to try printing wheel hubs. Stopping printer and certain point and pushing bearing is a neat idea, not going to lie. One thing that I am curious, you are printing both inside part and outside hub, at the same time. Did you get an issue, that two elements fused together, and thus it didn't rotate in the center? I've also seen it's approximately your build 17, so I believe you polished it as much as you could. :)

[Aurorasaurus]

14 minutes ago, Krxlion said:

Great work @Aurorasaurus, maybe one day I will convince myself to try printing wheel hubs. Stopping printer and certain point and pushing bearing is a neat idea, not going to lie. One thing that I am curious, you are printing both inside part and outside hub, at the same time. Did you get an issue, that two elements fused together, and thus it didn't rotate in the center? I've also seen it's approximately your build 17, so I believe you polished it as much as you could. :)

Thank you very much! The two parts are slightly joined together, too much for me to break apart by hand. I use some pliers and put the two ends in two opposite holes and then I am able to twist it free. At first it spins with some resistance but a drive later they spin just fine. This is probably close to the 6th actually distinct design. Fusion just ups the version number every time you save. I think there is a lot further to take this idea, since it's so easy to design and make new hubs this way.

I've been toying with the idea of selling them, for as low of a price as I could while still taking a small profit, maybe 4 euro each. But I suspect the market for such a thing is tiny, and the shipping would be outrageous to the EU from NZ... Not to mention people seem to be more inclined to use RC wheels than lego wheels. I just have two buckets full of lego wheels so it makes sense for me.

[Krzychups]

Well done! I see you are driving your Lego rc cars aggressively and it doesn't break. I shared step files of my wheel hub with @Aurorasaurus. If someone want to use them, you can find them here. 

On a side note, I still have to wait for my custom metal parts for my wheel hubs, because this is not a typical order, I commissioned it more on a friend basis. I tried to print one my of wheel hub with the bearing inside, it's quite strong. Anyway, I'll share them with you!

Edited February 19 by Krzychups

[HorcikDesigns]

Well, I like this print-in-place approach very much. Good job! 

[Aurorasaurus]

34 minutes ago, HorcikDesigns said:

Well, I like this print-in-place approach very much. Good job! 

Thanks very much!

40 minutes ago, Krzychups said:

Well done! I see you are driving your Lego rc cars aggressively and it doesn't break. I shared step files of my wheel hub with @Aurorasaurus. If someone want to use them, you can find them here. 

On a side note, I still have to wait for my custom metal parts for my wheel hubs, because this is not a typical order, I commissioned it more on a friend basis. I tried to print one my of wheel hub with the bearing inside, it's quite strong. Anyway, I'll share them with you!

What are the metal parts you're waiting on again? Threaded rods and U joints, iirc?

I'm looking at getting an LED lightbar like for a proper rc car, and proper RC shocks. @Krzychups Did you fill your shocks with oil? Or were they fine without it. If they need oil I think it's not the solution for me at this time.

[Ryokeen]

9 hours ago, Aurorasaurus said:

If they need oil I think it's not the solution for me at this time

If you don't fill RC shocks with oil you can just continue to use lego springs, except maybe for the durability of RC shocks. But the oil in them is what makes them proper shock absorbers.

[Krzychups]

11 hours ago, Aurorasaurus said:

Did you fill your shocks with oil? Or were they fine without it.

Well, not yet. I haven't finished my crawler yet, but today arrived my order from Aliexpress, so in a near future I'll finish it. It seems to me that some of my shocks are a little bit filled, I can feel it. In any case I have to do that. It's useful in fast vehicles. Remember to use a proper viscosity of oil.

RC shocks are great, they're robust and I can regulate the stiffness and damping. I strongly recommend them. It's hard for me to say which specific brand, I just don't know. 

Here's the Ryokeen's answer:

On 3/10/2024 at 1:18 AM, Ryokeen said:

@Krzychups I for myself can't recommend a specific brand. But i look for total width, so that it's max 2 studs wide, reviews about how likly they are to leak, a shaft of at least 3mm diameter and spring adjustments via a thread and not plastic spacers. Else maybe look it they are used as replacement parts in a similiar type or car that you want to build. Cause what often isn't stated or at least i never found it, is how big the holes in the shockabsorber are. You know the moving disc inside that builds the resistance against the oil. Cause i have some slim line shock absorbers that are pretty good, except that the holes are so small that even 100cps/cst oil is to thick for them to properly extend in less than 3 secs :D

11 hours ago, Aurorasaurus said:

What are the metal parts you're waiting on again? Threaded rods and U joints, iirc?

Yes, nothing new, they're still the same.

Edited February 19 by Krzychups

[Krzychups]

Does anyone know what is the differential in Zene's differential frame? I guess it's 1/16 or 1/18 scale diff. I'm curious if I can make a diff frame myself with 3D printed parts (from nylon) instead of metal ones. Any thoughts on this? I can't open the differential frame because one screw is attached very tightly and I would damage the screw head in this way.

Edited February 27 by Krzychups

[Aurorasaurus]

4 hours ago, Krzychups said:

Does anyone know what is the differential in Zene's differential frame? I guess it's 1/16 or 1/18 scale diff. I'm curious if I can make a diff frame myself with 3D printed parts (from nylon) instead of metal ones. Any thoughts on this? I can't open the differential frame because one screw is attached very tightly and I would damage the screw head in this way.

No idea, maybe you could figure it out based on the parts that go into the diff? They have a rectangle with two rounded sides for connecting to the diff gears. And I think we know the ratio is 1:1.6. But the biggest problem I see with making your own diff this way is the adaptors from lego to rc for powering the diff. Whats your plan for that?

[Ryokeen]

@Krzychups i've searched for them and they are(mesured mine) most likly this :

They added adapters for the drive pinion gear and the output shaft parts.

Quote

And I think we know the ratio is 1:1.6

The ratio is 1:2.65 (tooth counted)

Edited February 28 by Ryokeen

[Aurorasaurus]

2 hours ago, Ryokeen said:

The ratio is 1:2.65 (tooth counted)

Ahh, that seems a lot more accurate. I always thought 1:1.6 was wrong.

Edited February 28 by Aurorasaurus
Misclicked post before done typing ;-;

[Krzychups]

Thank you!

Is this a differential for any Wltoys RC car or a HSP part? It will make it much easier for me to search for such a part. I think I've seen differentials like the one pictured, but they often don't have the dimensions given. I also see that the gear diameter is 27mm, which is more than 3 studs (24mm). The Zene's differential is also a bit taller than 3 studs. 

9 hours ago, Aurorasaurus said:

But the biggest problem I see with making your own diff this way is the adaptors from lego to rc for powering the diff. Whats your plan for that?

I'll see how to do it.

[Ryokeen]

10 minutes ago, Krzychups said:

Is this a differential for any Wltoys RC car or a HSP part?

Yep it seems to be, could also find it on amazon labeled as an upgrade part for the following "SG 1603 SG1603 SG1604 UD1601 UD1602 1/16" Those are WlToys.

[Krzychups]

On 1/7/2025 at 8:18 PM, vergogneless said:

I also think I’ve found metal axles, which I’d guess are aluminum. Judging by the price per unit, I can’t think of what else they could be. But there’s no information about the material in the description:

Can you link these axles? 

On 2/28/2025 at 8:53 AM, Ryokeen said:

Yep it seems to be, could also find it on amazon labeled as an upgrade part for the following "SG 1603 SG1603 SG1604 UD1601 UD1602 1/16" Those are WlToys.

Thank you.

@Krxlion, I would also like to ask you about the AM32 ESC you have. Do you have the the Rhino ESC (it's expensive) or cheaper substitute? Can you see much difference between normal ESCs and this ESC? How does it compare to driving a RC model? I'm very tempted by the possibility of controlling the model precisely at low speeds.

[gyenesvi]

On 3/1/2025 at 1:17 PM, Krzychups said:

@Krxlion, I would also like to ask you about the AM32 ESC you have. Do you have the the Rhino ESC (it's expensive) or cheaper substitute? Can you see much difference between normal ESCs and this ESC? How does it compare to driving a RC model? I'm very tempted by the possibility of controlling the model precisely at low speeds.

I'd also be interested in this ESC, do you guys have more info about it? I don't find too much original info on it by Googleing, just a few resale sites like eBay. It looks small and powerful though.

[janssnet]

Did some tests recently with an AM32 ESC (4 in 1, AM60II, Skystars). If you want to use it for a crawler in 'Sinusoidal Startup' mode, it is great. Great torque at low speed.

If however, you wish to use the 'Car type' mode (which includes 'reverse breaking') my experiments were less successful. Too little torque at startup, car didn't start, just stuttering. 

AM32 Configurator tool is great (https://am32.ca/configurator) and, if you support his Patreon site, you have access to creator: Alka Motors. He is very supportive.

To configure the AM32 you need to have a drone (BetaFlight) Flight Controller. 

Edited March 3 by janssnet

[Krxlion]

I will try to give  more update on the am32 and motors sooner, but currently I have terrible private situation, and I couldn't focus on Lego stuff almost for a month now. Only browsing your stuff guys, and pretty much that's it, sorry.

[janssnet]

Happy to share my latest project: 3D printed LEGO boat (of course with BLDC motor ;)

Hull is very compact and can be printed in one piece.

Most interesting part is the drive train and prop shaft. The 2L Pin Connector fits nicely in the printed (8mm diameter) prop shaft. The 5.5L axle with end stop goes into the Pin Connector. Turns like a ball bearing and is waterproof..

Please notice: no rudder! Prop steering using the universal joint.

Short video here (running a 2S Lipo):

https://drive.google.com/file/d/1mmEY6Vb6IYZa8Du-E9WFCwVLy3QTTjXD/view?usp=sharing

Edited March 16 by janssnet

[Aurorasaurus]

On 3/4/2025 at 11:54 AM, Krxlion said:

I will try to give  more update on the am32 and motors sooner, but currently I have terrible private situation, and I couldn't focus on Lego stuff almost for a month now. Only browsing your stuff guys, and pretty much that's it, sorry.

Take your time, I hope things are better now.

44 minutes ago, janssnet said:

Happy to share my latest project: 3D printed LEGO boat (of course with BLDC motor ;)

Hull is very compact and can be printed in one piece.

Most interesting part is the drive train and prop shaft. The 2L Pin Connector fits nicely in the printed (8mm diameter) prop shaft. The 5.5L axle with end stop goes into the Pin Connector and runs waterproof as well.

Short video here (running a 2S Lipo, 3S to be tested soon):

Looks promising, but the video is private sadly.

That prop must have a crazy amount of speed, straight from a 2200kv motor!? Crazy!

[Krzychups]

Hello everyone! 

I'd like to share the results of my work with you.

I've done reverse engineering. It looks almost like Zene's differential, maybe with some small changes. Instead of metal adapters, I'll print them from nylon (the black parts). I highly recommend printing from strong material. The final cost is about 4 times cheaper than buying the differential from Zene. The needed parts are:

• the 3D printed adapters and housing,
• 4x M2x10 screws and 4x M2 nuts (you can use different types of screws, but the max head screw diameter is 4 mm),
• the differential,
• 1x M3x3 DIN 913/ISO 4026 - hexagon socket set screw with flat point,
• 2x 12x8x3,5 mm bearings (they comes with the diff) and 1x 15x10x4 bearing,
• the 4 mm diameter metal rod cut to about 11 mm with a flat surface on one side.

 

 

By screwing the hex socket set screw, you lock the shaft with the attached gear. What type of grease should I use to lubricate the sprockets and is there any point in filling the diff with rc silicone oil? 

I'll share the stl files with you.

So, what I need to do is to buy screws and other parts! What do you think about it? 

15 hours ago, janssnet said:

Happy to share my latest project: 3D printed LEGO boat (of course with BLDC motor ;)

Cool!

Edited March 16 by Krzychups

[Krxlion]

I see you have moved more and more into boat stuff @janssnet. That's not exactly my cup of a tea, but when I see them in action, I would like to try one out in my nearby river. ;)
@Krzychups I am looking forward to your project, do you know when we will see first build prototype?
I watch all @Aurorasaurus clips on YouTube, how do you get so much time to build all of these in such a short time, man! :D Great work!

Regarding AM32 ESCs, I think that these types of ESCs are a future solution. For me, it is not only for crawlers, but it can also be used in "standard" cars. Having an option to program the ESC is great, because you can suit it to your model.
Currently, I have 3 different BL motor types (fully build and tested), and two different AM32 ESCs:
- 40A https://pl.aliexpress.com/item/1005008013717329.html?spm=a2g0o.order_list.order_list_main.40.57a21c249lGTr5&gatewayAdapt=glo2pol
- 80A https://pl.aliexpress.com/item/1005006877273669.html?spm=a2g0o.order_list.order_list_main.49.57a21c249lGTr5&gatewayAdapt=glo2pol
The first one is much suited for Lego Technic builds, even for 1:10 crawlers. I am building and testing my Technic TRX-4 Land Rover Defender for past 4-5 months now. I have even finished it once for the bigger AM32 ESC (80A), and my biggest motor, but the motor consumes so much power, that my 80% of batteries couldn't handle power delivery (I even bought a few that should work, but capacity on them was the issue).

Now I am rebuilding the model using similar to A2212 motor, with 40A AM32 ESC. This setup is far lighter. I have prepared a temporary 3d-printed technic case for all my RC components and results are promising.

Regarding what HyBricks mentioned on AM32 ESCs, I could reverse brake in my case, there is also an option to program how the model behaves when throttle isn't pushed (for example: force brake in that scenario). This whole AM32 feels like sandbox, and I am sure people will figure out the best settings for regular cars, if there is a need for.

If you got any questions, feel free to ask, I will answer them once I got some spare time. ;)

[Krzychups]

Thank you @Krxlion for your reply!

The 40A ESC looks very small and it's also much cheaper. I don't think I'll use stronger motors than the a2212 BL motor in crawlers, so it will be suitable, won't be? Are there any bigger differences between the 80A and 40A ESCs?  Regarding my crawler, I was faced with the question of whether to buy this ESC. As I wrote earlier, I really want to be able to control the model accurately at slow speed. I only need to rebuild my crawler with planetary wheel hubs and make different transmission. Now it looks like this: 

 

Well, it's a bit dirty. It a sturdy and simple chassis. Looks much better than before.

2 hours ago, Krxlion said:

I am looking forward to your project, do you know when we will see first build prototype?

I expect to build the first prototype in no more than 3 weeks, but I'll have to wait a while before testing it in a RC car.

Edited March 16 by Krzychups

[Krxlion]

1 hour ago, Krzychups said:

Thank you @Krxlion for your reply!

The 40A ESC looks very small and it's also much cheaper. I don't think I'll use stronger motors than the a2212 BL motor in crawlers, so it will be suitable, won't be? Are there any bigger differences between the 80A and 40A ESCs?  Regarding my crawler, I was faced with the question of whether to buy this ESC. As I wrote earlier, I really want to be able to control the model accurately at slow speed. I only need to rebuild my crawler with planetary wheel hubs and make different transmission. Now it looks like this: 

 

Well, it's a bit dirty. It a sturdy and simple chassis. Looks much better than before.

I expect to build the first prototype in no more than 3 weeks, but I'll have to wait a while before testing it in a RC car.

Yes, you may use it with A2212 BL, no problem. I got a motor slightly more powerful (the dimensions are the same), and got no issues.

ONE THING TO NOTE THOUGH: I would advise to solder thicker wires (f.e. 16AWG). I just bought another cheap ESC, and took battery and motor cables from it. I took this one as "a part pack": https://pl.aliexpress.com/item/1005006958421845.html?spm=a2g0o.order_list.order_list_main.30.60c71c241GVXc6&gatewayAdapt=glo2pol
For crawling or cruising, that ESC has no issues. I would need to test how it would handle more harsh tests, like buggy with 75-100% power for 10+ seconds, but I don't usually drive like that. :D

The only difference between 40A and 80A is of course size, but the 80A has thicker wires, and a button to change how much volts will receiver get (and thus components like geek-servo). There could be a benefit from that, if you would give geek-servo more volt, but you could also fry it. :D
For models around 2kg, I believe geek-servo powered by standard 5 volts is enough. I though tried giving it more power in my tests, but I guess internal plastic gears will break before you will notice real benefit from it.
I don't use 80A anymore to be honest, simply because it is bulkier. Not only that, but I try to squeeze every RC component in a tight spot (preferably a 3d printed technic case), and that is harder with bigger ESC.

If you think about giving AM32 ESC a try, buy 40A version plus USB adapter to program it. You will probably receive a software to program it, just look on YouTube (holmes hobbies got a detailed video on that topic).

Regarding your chassis, the transmission attached to BL motor is kinda bulky, is there no way to shrink it down? I love though the oil shock absorbers, I am starting to feel that I need to get my hands on them. :D

Maybe I will try to create a post today on my model. I got some spare time (finally, yay! :D).