[ Proto ] The Small and Fast Brushless Lego Buggy

[vergogneless]

Hi all !

It's my turn to share my experience with Lego RCs powered by a brushless system!

I've been building Lego RCs for about 8 months, desperately seeking power on a small scale. I only work with 1/20 to 1/24-26 scales.

I obviously started with Lego motors. I tried everything, and after a few weeks, I came to the same conclusion as everyone else: it's awfully slow and imprecise.

 

I even bought a Buwizz 3.0.

And honestly, I thought it would be THE solution, the key to everything. What a disappointment, this thing is just WORST. It's a shame to sell such an expensive product and make so many promises... The reality?

-The buwizz goes into safety mode as soon as you really want to have fun (and you have to plug it in to reset it!!!!)

-The proportional steering (with an L motor) is laughable, it's not even at the level of the worst proportional steering on the worst classic RC!

-The touch control is awful, no possible driving

-There is an application to use a controller, it's true that it's better (thanks to its only developer, Buwizz should take note!), but it's still finicky, and still doesn't measure up to a classic RC.

 

All of this has definitively pushed me towards conventional RC components. And that's where the ordeal began. Nobody, I mean absolutely nobody, was able to provide a list of all the necessary components for noobs.

That's what I thought for many weeks. In reality, I think I was searching incorrectly. But it's also fair to say that the Youtube algorithm wasn't much help either. I spent dozens of hours on it before it finally showed me current videos about brushless systems for Lego. Mainly Russian. Because they are the pioneers in this field.

Unfortunately, before being really enlightened, I spent too much money on classic RCs that I was trying to make compatible with Lego, a bit randomly. There was some good and some bad!

I started with a WLToys 284131 1/28. I built this:

Luckily, the motor is Lego-compatible, it easily fits into a 7x5 frame. To be completely honest: it's not bad! The whole thing is compact! It already works better than a buggy motor! The steering is precise and very enjoyable!

But it's still brushed, it heats up like crazy, and I can feel that the tiny motor is struggling. And it's not really possible to make a bigger model. I've reached the limits! Plus, there's no suspension and it's a bit heavy for the motor.

That being said, at the time, it seemed more than honorable to me and pushed me to continue in this direction. I looked for something bigger.

 

So I bought a WLToys A959. But it was a mistake. The motor is absolutely not Lego-compatible, too complicated.

 

Big disappointment and wanting to give up everything. Which I did for a little week. Thinking that there is no solution. Or that they are jealously guarded by a very small number of people. As if nobody wanted to disclose the secret.

Then Youtube suddenly sided with me, I came across a first video by a Russian, then finally the algorithm unlocked, and it was almost a flow of examples, creators, functional systems, etc.

 

Then little by little, I noticed that there was a consensus on the A2212 1000kv motor. Wait, is it really sold for less than €6? Bingo!

And it all started from there. I gathered informm here and there to make a list of compatible components, and this time it was certain, other people use them and it works!

 

To summarize, here is the list of what you need:

-A2212 1000kv Motor = 6€

-Bidirectional 50A ESC = 13€

-Gray Geek Servo 360 or SG90 = 10€

-Dumbo RC X6FG + Classic or Mini X6FG receiver (with integrated gyro!) = 34€

-2S battery = 10€

But you will need to buy 2-3 other small things and equip yourself with some materials to prepare everything. I'll even give you a secret at the end of my story!

I particularly bought:

-A wire stripper

-A soldering iron + tin -3.5mm banana plugs to solder to the ends of the ESC

-A male Dean T connector (or other, depending on the female connector present on your battery)

-Extra strong glue

-Baking soda to make the glue stronger than concrete

-M3-8 screws to attach a piece to the motor and thus make it compatible with Lego architecture

*You will need to solder the banana plugs to connect all the components. That's about it. 

And so, here is my very first full brushless Lego RC prototype!

 

 

 

 

 

 

 

 

 

 

Weight: 408g

Length: 16.5cm

Width: 13cm Height: 5.5cm

Autonomy: between 1 hour and 1 hour 30 minutes, without power restriction, and without holding back!

Efficient suspension system that takes up literally no space and doesn't weigh a single gram thanks to the elastics and the 45590 piece to connect the axles to the chassis. The car absorbs absolutely all the bumps and does not suffer from the rebound effect.

No room for a differential, so the motor is connected directly with a 1:3 ratio (I am primarily looking for acceleration). It is mounted directly on the rear axle.

The chassis is somewhat tiered, as the ESC is attached underneath and the battery is on top (with the receiver).

The servo motor is directly attached to the front axle. It is a Geek servo, already compatible with Lego by default.

I used quite a few special parts, including beams with alternating holes. A true game-changer.

The weight is fairly well distributed, and the cross construction is solid. Everything is locked in X, Y, and Z. The gears never jump, not even once, even after jumps, rapid accelerations, etc! The secret is at the end...

The vehicle is as enjoyable to drive as a conventional RC. Ultra-precise and fast steering. It has such acceleration that it flips over if I accelerate at full throttle.

Pure pleasure, it goes anywhere, jumps everything, absorbs everything, without flinching, without holding back on the throttle, ever, like a conventional RC... I didn't activate the gyro because it wasn't really necessary, and I like the somewhat technical driving!

 

Although I consider this achievement a success, I still note some flaws:

-The gears are exposed

-The components are exposed

-No protection at the front, if it hits, the steering can jump a few notches

-A little more friction and movement due to the plastic

 

What I'm going to do/improve on future versions:

-Switch to 3S

-Activate the gyro, otherwise, it will be too complicated to drive

-Switch to a 1:2 ratio for more top speed

-Add a wheelie bar

-Better cable management

-Protect the gears as best as possible

-Make a simile body to protect the components as best as possible

-Add LEDs 

-Introduce metal parts (especially gears and wheel hubs)

 

And what is the secret that I promised you? It may seem trivial, but it is actually the essential and indispensable element. It will solve most common problems related to the fragility of plastic and overheating due to friction.

This secret is... silicone lubricant! Simply use it liberally, spray the gears and moving parts before each use, and you will never again burn your parts, and you will reduce friction almost to nothing! Personally, I use WD40 in an aerosol can.

 

If you have any questions or would like to react, I would be honored to hear from you!

Edited April 27, 2023 by vergogneless

[vergogneless]

Little uptade, for the V2.

I have further solidified the motor mount. I also installed a body with my limited skills, but the main thing is that all the cables and components are now protected.

As the vehicle has grown a bit, I decided to change the battery. I am switching from a 2S 25C 1050mah to a much lighter one, still 2S 25C but this time with 400mah.

It's actually sufficient, providing about 25 minutes of autonomy and avoiding any excess weight.

And the battery is finally easily replaceable!

 

 

 

 

 

[Daniel-99]

The bodywork is coming nicely!

Have you tried to implement the positive caster angle to the front axle?

[vergogneless]

1 hour ago, Daniel-99 said:

The bodywork is coming nicely!

Have you tried to implement the positive caster angle to the front axle?

I didn't think of that! Thanks for the idea, I just implemented it :D Test drive tomorrow...

 

 

 

[vergogneless]

The day is rainy and I cannot really test the new handling. Nevertheless, I have done a few laps around my place and I can feel an improvement. I am eager to push the test to the limit!

I will also test with the gyro to be able to make the comparison!

 

Furthermore, I am now introducing the V3 with a lot of modifications:

-Positive caster angle

-Some additions to the bodywork, notably a reinforcement of the rear wing which tended to come apart.

-Sanding of the 2 ball heads underneath the chassis (which hold the elastics). What remains is more than enough to hold the elastics.

For the 3rd central ball head underneath the chassis, I decided to move it, by cutting the axis to keep only the head, and gluing it higher with super glue. All of these modifications give me half a centimeter of ground clearance. I noticed that they had already scraped quite a bit. So, I gain in suspension travel and stability in case of road irregularities.

-Light sanding of the servo motor connector heads to avoid any parasitic friction.

 

 

 

 

 

 

 

That being said, I am not really fond of the front of the vehicle, aesthetically speaking, but I don't know what else to do or how to do it differently. Any suggestions?

[Jurss]

20 hours ago, vergogneless said:

-A little more friction and movement due to the plastic

One of the main reasons, lego doesn't make anything powerfull and fast, as firction causes wear, and also plastic is not so tough.

[vergogneless]

I do not entirely agree. Many successful projects would prove you wrong. It is possible to minimize frictions or movement with improved parts, which may not necessarily be more expensive than spare parts for a real RC. Moreover, they are reusable.

Certainly, if we are talking about heavy or very heavy models without improved parts, it can become quite troublesome. However, users who design such models generally make efforts to overcome these issues, just as in any hobby where investing can lead to better outcomes.

Finally, in the case of light models like mine, frictions and movement have little impact and can be resolved even more easily :) 

[vergogneless]

The sun had come out, and I was able to take my driving test!

I noticed many things that need to be improved for the V4.

 

 

Firstly, with the positive caster angle, the handling is better. That's a good thing.

However, on this rather rough terrain, I noticed that the vehicle tends to flip over. I believe this is due to the front suspension being too loose in its left-to-right movements (thanks to the rubber bands).
-So, I will make it stiffer.

I also noted that the tires are not held onto the rims at all and completely lose grip on the rim, which spins freely on strong accelerations.
-So, I will glue them to the rims.

During the rollovers, the servo motor sometimes scrapes the ground.
-So, I will protect it.

I wanted to try the gyroscope, but the receiver is not securely attached, making it unusable.
-So, I will securely attach the gyro.

I noticed a weakness in the front suspension at the point where it connects to the chassis.
-So, I will address that.

And finally, the vehicle wheelies very easily, which inevitably leads to an accident.
-So, I will install a wheelie bar.

 

 

[Johnny1360]

Very interesting, I am most interested in how you achieved positive castor angle.

[vergogneless]

14 hours ago, Johnny1360 said:

Very interesting, I am most interested in how you achieved positive castor angle.

Thank you!

The modification was relatively straightforward in my case due to the overall design of the vehicle. I can even adjust the angle if needed.

Let me show you some photos for more details.

 

 

 

 

Regarding the progress of the V4, it will be completed today. I just need to glue the tires and design a wheelie bar.

 

Also, I completely forgot, but in a few days, I'll receive my carbon axles. So, I'll install a single solid axle on the rear. Currently, I haven't had any issues with my two Lego axles connected together, but it's better to be safe than sorry.

At the beginning of next month, I'll order a metal gear kit with 8T+12T+20T+24T+40T gears.
To try out different gear ratios.

And, most importantly, to prepare for the arrival of a small 3S 450mAh battery that will push the car to its limits!

 

Edited April 29, 2023 by vergogneless

[vergogneless]

I have completed the work on this 4th version. I have done everything that was planned.

In addition, I have added more steering angle. I was set at 50% on the remote, but I could go up to 80... Just for that, it's like night and day!

Furthermore, I completely redid the servo motor support, which is now perfectly held in all directions! I also added a bar under the front axle to eliminate some of the remaining movement.

By the way, I fixed the gyro, which works well when the car is stationary and I shake it. But I have the impression that it behaves somewhat erratically during driving, not fulfilling its role (I tried to adjust its sensitivity, but that doesn't seem to be the problem). So I wonder if there is a specific way to position it?

I tested it briefly at home and I am very satisfied. I have almost nothing to say, I am impressed by the result, which is well above my expectations. Now that the tires are glued and I have my full steering range, it has much more precise and responsive reactions. I can take turns in a slide, I can drift, etc. Very pleasant to drive, very smooth, keeps its trajectory. With so little friction, it doesn't brake by itself during decelerations and naturally continues in free-wheeling. And the acceleration is so lightning-fast that you can't even hear the gears straining (by the way, they have remained intact since I started using them - Thanks to the silicone lubricant and the strong motor mount)!

I can place it alongside conventional RC cars without any problem. And at this scale, it would beat a couple of them :D

If the next outdoor driving test is entirely conclusive, I think I will have explored all possible modifications and improvements for stage 1.

I will only have to wait for the arrival of the 3S battery to begin stage 2. The vehicle will have between 40% and 60% more power, and certain things will probably need to be adapted. The metal gears and carbon axle will become essential at that point!

 

 

 

 

 

 

I will be making a video in the next few days!

[Johnny1360]

Right on, thanks for responding, it is great to see how much fun you are having, pushing LEGO to the limits. Looks like the glue bottle got a little out of control there, I wonder if maybe there is a better way of preventing tire slippage on the rim.

[vergogneless]

15 minutes ago, Johnny1360 said:

Tout de suite, merci d'avoir répondu, c'est formidable de voir à quel point vous vous amusez à pousser LEGO à ses limites. On dirait que la bouteille de colle est devenue un peu incontrôlable là-bas, je me demande s'il n'y a peut-être pas un meilleur moyen d'empêcher le patinage des pneus sur la jante.

What a hassle, my glue tube was clogged, so I had to make a cut with scissors, and it was a mess to apply ! The white substance you see is baking soda, I just need to scrape it off.

I don't think there's any other way, you have to resort to gluing when you reach a certain power level. Otherwise, there are ways to attach real RC wheels, but it seems to be only for hex sizes of 12mm or 17mm, which is not suitable for my scale.

[Brano]

@vergogneless hello could you please add more photos of steering? I dont know how to build this steering  thank you😀