[MOC] Fast RC Cross Kart powered by BuWizz

[Anto]

This is my new MOC!

I wanted to make again a buggy but with a RC motor. It had to be as compact as possible and feature full independent suspensions. 

I wanted to make a different design. Generally for a buggy, you put two panels on each side and that's done. But I managed to change by doing something that needed more work (and that is orange!).

I also tried to incorporate many little details: headlights, radiators, exhausts.

This kart is of course powered by a BuWizz, to have more power! And it's way enough to play indoor or on a terrace!

I spent much time on making a good chassis. At the rear, a suspended axle was required to make the chassis more compact. I centered the weight, so the weight balance is excellent! The grip is well balanced between the front and the rear, it's way better than for my previous buggies. 

The suspenion is really soft, so when you make the model fall from some centimeters, the bottom of the chassis touches the ground. But this allows having a bit of roll in the turns, which is quite nice to see and gives more realism - furthermore it makes the suspension really efficient.

 

And I done building instructions! 

They are better than the ones of my Ford Mustang Hoonicorn. I use many buffers. It's a functionnality of LPUB3D that is useful to change certain sub-assemblies between two steps. It's also possible to make appear and disappear helper arrows or to change the position of some parts, as you can see when I fix the rear axle.

Spoiler

 

The "little" inconvenient is that it requires a lot of work. During the modelization, we have to dupplicate every sub-model that will change. For instance there are 2 rear axles, but in each axle there are several other sub-models (left shock absorber, right one, left yellow gaz tank, right one...). Finally for this model I have 89 sub-models, for a model of 450 parts. 

The instructions are available here: https://rebrickable.com/mocs/MOC-40021/Anto/fast-rc-cross-kart-powered-by-buwizz

And I'll try to make a video!

[kbalage]

Great model, I really like the size and all the functions! Can't wait to see it in action :) 

About the buffer exchange challenge in LPub3d, I do feel your pain. It's so "fun" when you have an assembly that you need to move 100 steps later, so you need to include that assembly hidden with buffer exchange through those 100 steps :) 

[Jurss]

Cool buggy. Video is a must.

I just don't get it, where there is full independent suspension and why there are u-joints at the back?

[Anto]

Thanks!

 

On 4/18/2020 at 11:44 AM, kbalage said:

About the buffer exchange challenge in LPub3d, I do feel your pain. It's so "fun" when you have an assembly that you need to move 100 steps later, so you need to include that assembly hidden with buffer exchange through those 100 steps :) 

Exactly, but I think it's worth it!

 

On 4/18/2020 at 12:20 PM, Jurss said:

I just don't get it, where there is full independent suspension and why there are u-joints at the back?

By "full independent suspension" I meant that the movement of a wheel doesn't depend on the one of another wheel. The rear wheels arent on the same pivot (as on a quad for instance, the rear wheels are linked, which is not the case here with the suspended axle).

I'm not sure that the U-joints are really useful, I used them to try to reduce the friction due to the wheels bending their axle. So they are either useful or useless without affecting the performance.

[Jurss]

50 minutes ago, Anto said:

I used them to try to reduce the friction

Now all the friction from wheel is on that black part. I think, with some solid connection, friction will be smaller.

[amorti]

1 hour ago, Anto said:

So they are either useful or useless without affecting the performance.

That's fine until or unless one of them breaks.

Ludicrous mode will always find the weakest point!

I'd use a straight connector with a 5.5 axle each side so it couldn't escape.

Cool buggy though, chapeau!

 

Just realized it's already a 5.5 

Edited April 19, 2020 by amorti

[Anto]

About the U-joints, I don't currently know if they will balance the pressure on the axles or not as I hope, I'll see with time. I have worked a bit on a small chassis which has got a 14L axle at the rear, and with time, the axle began to be sawed by the outside edges of the liftarms (close to the wheels), whereas the inside edge there got few damage. So I thought the pressure could be better balanced using U-joints, I'll see...

@amorti Thanks! And yes the Ludicrous mode reveals the weakest point of every model, that's why I use 5.5L axles! :)

 

Edited April 21, 2020 by Anto

[Lego_Loki]

Where did you get the gear rack for the steering? I've been looking for that one piece for a long time and I cant find it. also, what is the part number for it?

[iLego]

17 hours ago, Lego_Loki said:

Where did you get the gear rack for the steering? I've been looking for that one piece for a long time and I cant find it. also, what is the part number for it?

https://rebrickable.com/parts/6574/technic-gear-rack-1-x-2-with-ball-joints/

[Anto]

That's it @iLego ! I got this part from the buggy #8048.

 

By the way, I published the video!

 

It was pretty difficult to make it since I used the GoPro Max. I recorded most of the videos in 360° and then reframed them to follow the kart exactly as I wanted. But it wasn't so easy.

Currently, the only way to edit videos from GoPro Max using all the features available is to use a plugin in Adobe Premiere Pro. However, this software isn't well optimized, and editing a video in 360° requires a really high performance computer that you can't even find in sci-fi movies (the videos of the GoPro Max are in 5.6K). To be able to use a video in 360° into an editing software, it's necessary to convert it in another format that the software can read. I got 140Go of videos after conversion. Yeah. I was not able to use Adobe Premiere as it crashed when I tried to import a video on the timeline...

So I used Hitfilm as usual, which is way more optimized than Premiere. I couldn't edit the videos as well as Premiere can do but I could make a video, which is not too bad. ^^ I encountered many issues, but I finally succeded in getting a video! 

 

See it as a training for the Gymkhana 4 that I'll try to do this summer. And tell me what you think about the video of the kart, I want to use your opinion for the upcoming Gymkhana.