[MOC] RC Karting (BuWizz)

[technic_addict]

2 minutes ago, Anto said:

Thank you a lot for your work Thorsten!

@technic_addict  I put my kart on Rebrickable: http://rebrickable.com/mocs/MOC-8322/Anto/rc-karting-buwizz/#comments

(And I changed the instruction by Thorsen's ones)

Thanks!  When kids come over they will have a blast driving this.   Hopefully controls on phone work ok.

[AFOLegofan66]

Thanks for the great instructions....just built this and tried it out...really FAST!! I put a bit of duct tape on the motors to protect them a bit. I was driving on new pavement so I didn't really need it. This is the most fun from a Lego mOC yet and Buwizz is the way to go for some extra juice!!

[MadMax1998]

First RC MOC I ever built, and premiere of my own BuWizz brick! I was looking to try the BuWizz out with a fast and easy to assemble model that didn't require part sourcing. Ended up with this:

Extremely fast in Ludicrous mode, but hard to steer. Never goes really straight due to the loose steering link. Building instructions use exotic parts that could easily be replaced by common ones, such as full-length bushings instead of sleeves. Some instructions are unclear or finicky to build, like the cable routing. Lots of eye-candy that can be left out to save parts. Mainly used parts from 42000, 42039 and 7347, some from 42009 and 42095 (motors, sleeves, black discs). Had to add servo separately.

Unfortunately the motors were scratched by the ground. Not a big deal, but the front panels took quite a beating when the kart inevitably crashed into a curb. These parts were all used anyway, but the panels at the front really should be replaced/protected by common parts such as axles.

All in all it was a nice little build and driving it was lots of fun, but the next RC model I'll build has to be sturdier and easier to control!

Edited August 5, 2020 by MadMax1998

[amorti]

Seems like it'd be easy enough to drive the steering wheel off the back of the servo and have it move with the steering, maybe a rubber band transmission?

[Anto]

Thank you for the review @MadMax1998! 

Did you try to use BrickControl App? It's way easier to control this model with a game controller than a phone.

The kart doesn't go exactly straight but it's not due to the little play in the steering. The play and the little caster angle allow the front wheels to be perfectly straight. The fact that the karts doesn't go perfectly straight comes from the transmission. The torque of the motors bend the chassis a bit. If you make a test, you'll see that the kart can turn better in a direction than in the other. It's from the transmission. But since I wanted this model to be really fast and light, to me it was not a great problem to sacrify a bit the maniability. It is still very fun to come really fast and shred the tires by steering quickly! 

Also to avoid damaging the parts it's better to drive this model on a perfectly flat ground. But we cannot everytime we wand to drive a MOC...

 

On 8/6/2020 at 2:42 PM, amorti said:

Seems like it'd be easy enough to drive the steering wheel off the back of the servo and have it move with the steering, maybe a rubber band transmission?

I never tried, but it could also be possible to move the steering wheel 2 studs down and directly use the axle of the servomotor. However I don't know how it would look like.