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20 minutes ago, gyenesvi said:

That's some amazing compactness there, interesting driveshaft.


Interesting method for the spring. Thanks for the suggestion.


Personally I consider even just the spring legal, since that is also a Lego part (and I have made a MOC with it in the past with the spring running on an axle), but I want a normal alternative for which you don't have to disassemble parts that are normally not disassembled (for that old MOC my alternative was a suspension with rubber bands). It's just a weird personal rule I have when I make MOCs :classic: 

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On 3/19/2024 at 6:22 PM, Appie said:

Finished the chassis for that new axle I posted earlier, inspired by AutoBacon's work

Looks great, small and compact but not flimsy. Do you have a file for it? Can't see how you hooked up the steering motor in such a tight place :D Also can't see how you won't win the next 56mm truck trial :D

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Thank you very much. I like how sturdy it is yet compact as well. I made it a little sturdier even since those pictures. Secured the connector at the bottom better near the knobgear on the driveshaft and used the battery box to prevent the base from tearing apart down there (mostly a security measure for when it tumbles, not something the drivetrain tears apart). 

I don't have a studio file yet, but I would like to make one. 

And yeah, I am looking forward to the next round, quite confident with what this chassis can do. At the end of May we go again. 

As for the steering, it was a little annoying, because the space between the axle of the motor and steering axle is 4 studs. I didn't want to use 24T gears to bridge that gap, since those would touch the liftarms to the sides of the motor. So I came up with this:


Not in the picture, but on the right side of this I placed a liftarm with half pins that act as stops above and below the top 2L liftarm from the motor, so the steering motor can't turn too far. Also, it's 5L liftarm between the 2 axles on purpose there, 4L had the tendency to get stuck on the lower rim of the battery box, this solution prevents that from happening. I have yet to have it happen at the top of the battery box, but then a 6L liftarm is an option. It being locked in by the battery box is something I like though. Making sure the whole mechanism won't run off axles. 

(also the tan axle from the motor is an axle pin. I used it as placeholder until I was done testing stuff)

Also, yesterday I made an attempt to lower the springs one stud:


In the end I didn't use it and reverted back to the original design. Obvious flaw is the springs not being able to move sideways naturally, but the suspension in general didn't work as smoothly as the previous design. And the axle as a whole felt a little less sturdy. Geometry with the new spring location felt off a little too. The spot I lowered them to is pretty much my only option and couldn't go wider there either or I'd touch the tractor tyres.

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Posted (edited)

I made a file for the chassis, available here:


It should be complete, but if you find any issues let me know.

Also something of note perhaps if you build this: when you press the front suspension so both springs have to compress, the movement is a little bit limited by the 12T gear from the steering that bumps into the L-motor. I have no issues with this, because for crawling action it's usually one side being compressed and not both. For one side being compressed it has no issues.

Edited by Appie
fixed image

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Great video Mahjqa. It was great fun. Thanks for hosting the event and making the video!

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