LEGO Purists ... please stop reading now ... the following will make your blood boil ...

 

Hi all,

t is the F1 season at the moment and I am getting back into Lego. The last time I "worked" on a Technic set, they still had the LEGO studs on them ... not anymore !

I recently purchased a 42000 set and was quite pleased with the mechanics and looks of it. I was also pleased to know that there is an option to motorize it.

To my horror, the motorization is pretty lame (lifting hood and flaps ?!). Was I expecting too much ?

Anyway, I digress ...

This post is a record of my attempt to properly RC motorize it, while still keeping the aesthetics of the 42000.

After a couple of weeks of evening research, I came to the conclusion that the LEGO electronics is not up to the job. They are just too bulky and the electronics is still stuck in the 90s ! Have LEGO not heard of brushless motors or LiPo power ? After seeing all the other attempts to motorize the 42000, I have decided to embark on my own journey. Here are my thoughts ...

MAIN AIM :

a) I like the engine block, so I'm going to do my best to preserve it.

b) Putting a battery box at the back is a definite NO-NO

c) Ripping out the exhaust tubings is OK as it is usually hidden under the hood.

d) IR control is a bit outdated ... Let's use 2.4GHz !

e) Use LiPo as they have the highest energy density vs weight. We are building an F1 car after all ! 
 

STRATEGY :

1) Keep LEGO differential (somehow I am very fond of the diff ...). Use a LEGO PF L Motor to drive the rear wheels. Looking at the unit, there should be some space below the engine block to fit it. Using a LEGO motor means that will be mechanically strong, and the L motor has lots of fixing holes. 

2) This is where it starts to deviate ... Use RC parts for the transceiver, battery, servo and ESC. This is because the RC (esp Drone) community has lots to offer here. Let's list the parts ...

i) Transceiver : I am leaning towards a Drone stick transceiver using 2.4GHz. These days, they have automatic frequency hopping, so less (maybe none) interference with other RC signals. Also, the drone transceivers have loads of channels (6-10) ... good for upgrade options (adding lights, sounds, more motors, etc ...). The only drawback I can see is that the stick throttle control is not sprung (return-to-centre). So it will be tricky keeping it stationary. (it will be wanting to nudge forward or backward). 

ii) Battery : LiPo, 11.1V (High V for more RPM). Was looking around and there seems to be a lot of options here in different sizes. Found some that will fit in the F1 sidepods. Will have to remove the exhaust tubes, but that is OK. As I am not using the PF IR receiver, 11.1V or 12.6V from the LiPo should be fine for the LEGO motor ... will need to check how much it heats up when stalled. Maybe add a Zener diode to drop the voltage slightly if needed.

iii) Servo : This is beginning to get tricky. I need to find one that will fit under the F1 front nose. There is not a lot going on in there, so I think this should be ok ... How to secure it to the LEGO ? Well, some nylon nuts and bolts of course ... and some custom plastic pieces I guess. This will be a Macgyver (1985) job.

iv) ESC : Since the Lego L motor is essentially a brushed motor (380 or 280 motor ? Can someone confirm ?), the standard RC brushed ESC (Electronic Speed Controllers) should work ? I have bought a PF extension wire to be modified so that it can be connected to the ESC.

FUTURE WORK  :

1) Add a brake light and motorize the flaps and hood as well ? (lowest priority)

2) Add a FPV camera (maybe one that looks like a driver in the driving seat)

3) Add SPEED. Replace wheels+assembly with one that have bearings, metal CV joint, differential, axle ...

4) Add sensors (speedometer, temperature, ...)

5) Add a soundbox ... realistic F1 sounds ?!

6) Maybe add a "brain" ... micro-controller ... make it autonomous ?

 

So that's the plan ... comments and suggestions welcomed !

 

Welcome here, you have quite a plan.   Glad to hear that your dark age is over.

Few questions?

Sbrick as a Lego friendly alternative to replace the IR reciever? It has bluetooth connectivity. I'm a happy user of them. One of our member (imrvai) made an application to pair the Sbrick with game controller trough an android device. Life saving solution for our kind.

Pf Servo motor does a fairly good job, you did not mention it, nor your concerns about it. By using that you have no problem with the fitting.

I'm using Lipo's too and frequently appologizing for doing so. But I'm happy with the 2S pack (infact I'm using 2 single cell) On long therm it is a safer voltage for PF elements although I know those motors are technically 12 volt designs, the Sbrick has a 10.5 v limit.

As far as I know Lego hasn't upgraded it's electronics to be fast because the main user group are children. If the creation goes fast and far the child follows it by runing out perhaps on a road, and could be hit by a car or something. So the reason behind the technology kept down is health and safety.

So long story short, I'm one of those who understand your demands, but probably you don't need to go that far to reach an acceptable performance.

 

Hi Attika,

Thanks for your post.

a) The Servo motor is too big and clunky to fit to the 42000

b) The Sbrick does look interesting ... But Bluetooth has limited range ...

I think electronics is not Lego's strong point ... 

Technic builders can do with some upgrades (Bluetooth, WiFi, Arduino, video, accelerometers, GPS, speakers, LCD, touchscreens, etc ...)

No worries, I didn't mean to stop you on this noble quest, I've just covered some intermediate solutions you might not concidered.  But you prooved that your heart is clear, so all I can say you won't be alone on the road.  

I'm a fan of fast things too, frequently using my rc buggy motors, Sbricks and Rc heli Lipo's. This combination satisfies me speed and powerwise. Feel free to look around on my youtube to see what is it enough for. (the ripsaw and the driftcar I'd offer into your attention) I understand though the limit is way beyond that (if there is one at all)

Edited April 14, 20177 yr by Attika

My 42000 is in desperate need of pf, I will stay purist and is 2 xl motors. Ir is for me as I love the controller.

This sounds like a good idea but will hopefully be fast.

Thanks for the comments everyone ... Will post some pics when it is done ... 

Might may take a while though as my wife and kids have other ideas for my free time ! (Plus the kids want help on their mind storm set!)

 

Edited April 15, 20177 yr by harpoon

Hi all,

I have failed to get an RC servo into the car ... the backup plan is to use the Lego PF servo motor ...

10 hours ago, harpoon said:

Hi all,

I have failed to get an RC servo into the car ... the backup plan is to use the Lego PF servo motor ...

Hi again, sorry to hear the faliure. The Lego servo isn't that bad, you'll be fine. 

Hi Attika,

Is there a simple way to wire a Lego Servo to a standard RC receiver ? 

2 hours ago, harpoon said:

Hi Attika,

Is there a simple way to wire a Lego Servo to a standard RC receiver ? 

I have no idea. Never gone that far. For me the buggy motor- Sbrick -RC LiPo combo is the recipe of speed. Didn't even get close to use other RC electronics. But I suppose if you wanna use those RC recievers, ESC (etc) than you should force the RC servo no matter what.

If you make a search on youtube:  "RC servo Lego" there is a few seemingly succesfull attempt to pair them up. 

https://www.youtube.com/watch?v=47JsLXTiusQ

or PF servo to RC reciever:

https://www.youtube.com/watch?v=Vcp_q1wI580

Hope it helps

Thanks ... looks simple enough ... now to get my hands on a servo motor ... 

Connecting RC receiver/esc to Lego motor and servo is likely possible, but if you connect high voltage you might burn them rather quickly. Yet, if you limit the voltage you probably won't get much "kick" .

If you decide to go all-the-way and use RC motors fit for that scale (i.e. a 540/550 brushed, or even brushless), you can find ways to mount RC servos/motors from threads by @JJ2 or myself (I'm sure there are others too).

hi all,

After more than a year away from this ... I found some time to work on this a bit more ...

a) After going back and forth between Lego and RC ... I have decided to go with a mixed setup,

-  6 Channel RC controller (typical flight controllers) 

- 3S (11.1V) LiPo power,

- Mini servo and ESC for motor control,

- but using a LEGO PF L motor. With the right wiring, it can be hooked up to a normal brushed ESC

b) I had a good friend 3D print a "housing" for my servo ... This saved space and weight, but was not 100% happy with the angles achieved. Will stick with it for now.

c) Preserved the rear differential as well as the front and rear suspension.

d) Preserved the V8 engine block and mechanical gears to open engine hood. Lost DRS flap control on the rear wing.

e) Preserved most of the cool pipes under the hood.

Surprisingly, the whole setup worked quite well ... apart from ... GEARS CLICKING ... so need some re-work ...

 

 

When I took the car off the floor, and ran it, there was a lot of vibration ... the double bevel gear (20 teeth) sometimes come loose and pops out ... loosing drive ... sometimes it is the motor axle itself that pops out ...

This is because I am not driving the differential directly ... but via another set of gears. This is because -

a) I wanted to preserve the V8 engine block ... and cannot direct drive the rear differential as it is 1 lego unit too close !!!

b) It allows me to play with different gearing ratios from motor to wheels.

However, this setup is not great and the whole chassis vibrates quite a bit. It means I have some work to do ... =)

Edited August 27, 20186 yr by harpoon

LEGO build completed ... Finally.

Reworked the gear coupling between the differential and the motor and it is no longer slipping. Really pleased with the end result ...