Aurorasaurus

28:20, 20:12. https://bricksafe.com/files/Aurorasaurus/tatra-8x8-first-edition/20241103_002720.mp4 Here's a video of it with that gearing.

Thank you, I appreciate the support :) The XL motors are geared 1:1 to planetary hubs, and with the Buwizz they get higher voltage thus higher rpm. I actually had it geared significantly faster before, but the motors were overheating after about 10 minutes of play.

Thank you very much! The requirements for next year are not out afaik, but I'm working on assumptions/a previous draft version. I have enough time on my hands on the weekends to build, and sometimes I get into that flow state where everything just works out. Music helps.

Thank you! The front 2 axles steer, so 4 wheels steer it.

It uh, seems to be missing doors... Otherwise, I'm shocked how quickly you made such a massive vehicle, it looks pretty good.

In preparation for next years Buwizz gathering, I thought I should start working on making a trial truck, among other things. I've never finished a trial truck build before, so I expected to run into some problems this time, but I suppose I got lucky and I didn't! As the title says, I also made this model in just 1 day on the weekend, which I'm proud of. I was inspired by a trial version the Tatra 813, from HT Group Racing. Here's a video of this truck. https://www.youtube.com/watch?v=uxFjTTEWORI Details The model has independent left and right side drivelines, each side is powered by 1 PF XL motor, geared 1:1 to planetary hubs. Steering is done by a C+/PU L motor, and has more slack than I'd like. The 1st and 2nd axles steer at different ratios, but due to the slack in the steering axle the difference is negligible. The model uses Tatra suspension pivoting off the drive axle. This is obviously not ideal, as it adds unnecessary load to the drive axle, but I was feeling lazy. The gears probably should skip, but I never heard them skip once when I was driving, so I guess its okay. Here's a mock up of the second axles swing arm, made especially to please the anti-color vomit crowd ;) And finally, a video of it in action! I recorded this on the weekend, with my phone hanging off my controller, so I apologize for the shakiness of it, and the wind noise. Thanks for reading, please feel free to ask any questions!

I also use 5mm to be a good size for the holes, and also use 6.2mm diameter for the counterbore. But I make my counterbore 1.05mm deep. Maybe this was only necessary for me because I typically print in high layer heights for speed.

Have you heard of PyBricks? Racingbrick has some good videos on it, and theres a thread here and a website with what seems like plentiful documentation. It allows you to pair an xbox controller straight to the hubs, but the downside is you need to recode it for every new creation.

Design a test piece with holes in multiple orientations, and test hole size in increments of .1mm. If its still hard to get a good fit, try increments of .05mm. If you don't have access to CAD software I could make one for you. Another thing could be you need to dry your filament and/or somehow temperature control the environment for your printer. Maybe external factors are impacting print accuracy.

I made a few 12t clutch gears from esun petg, and the teeth broke. I also tried a 28t clutch gear from pla and the internal clutch teeth broke, same with 24t and 2 module long clutch ring. So for gearboxes IMO there's no substitute for injection moulded ABS. But something that did work well for me was printing a 28t gear that slipped on top of a 16t clutch gear, using the strong clutch interface of ABS, and the good enough teeth of PLA, since at that distance from the axle the torque in my application was managable by the teeth. As for other things, I tried short reinforced cv joints, so I could make a 5l independent suspension system. Making those from PLA worked fine, but maybe wouldnt in a high wear environment like sand. Something that has worked great for me is 3d printing rims and body panels. For rims, I recommend printing in TPU so that the abrasive effect from the layer lines is mibimised. With PLA or other harder filaments, when you put the rim on and take it off many times you can wear down the pin and it will not hold the rim so well. Body panels from PLA have been fine for me. I just spend some time sanding and filling before painting and they come out just fine for my eyes. I've also made extremely specialised parts, but I'll talk about those another time.

Is there any reason you didn't attach the cv joints to the motor instead of attaching axle joiners to the motor and cv joints to the axle joiners? Was that because you originally planned to not use the planetary hub to gear down? I'm thinking about using the same method you used and was thinking I could save 4 studs this way.

I try to keep my parts out of the sun and dont have any problems with parts cracking. But my collection is definitely on the newer side. Also, how can we possibly not have even length liftarms by now!?

Would you be bothered by the layer lines? Or are you planning to use them just for mechanical parts, not bodywork? The only filament I've used that matches lego colors nicely is black :) Good luck anyhow, I'd be curious to see what you find. Maybe you can order filament samples instead of full spools?

I was looking for just that today, that motor size is 130. From my quick search, that size in brushless doesn't seem to exist. But I think it could be done somehow. As for the truggy, I love it, the climbing is amazing. I'd love to see some more footage of it at top speed on gravel/sand too though.

Its scary but really funny. Nice work making it move in such a fun way!

Just use brickcontroller, its so much more reliable. You just need to watch out and drive carefully because theres no current limits available in BC2 yet.

Nice model! I'm always surprised how compact you build, it really is impressive. Is this the same configuration you were driving at Buwizz gathering?

Could this be the marketing team changing how something looks? Like what happened with the two buckets/one bucket thing with the recent volvo excavator and truck set?

It looks good in the renders, and I like the removeable bodywork. How does the rear suspension work, are the light grey shock absorbers connected to an antiroll bar? 2 motors doesnt seem like enough to me, how is the performance?

I have the STL files I printed available here. Please note that the tolerances are not perfect for my machine, and probably wont be for yours either. You will need to modify the file to make it print and fit the gears inside nicely. EG the 24t gear doesnt ft.

I have printed one of these, apart from errors regarding the sizes of some of the holes (the 24t gear doesnt fit and the cv joint rubs a bit) the concept appears to work, defender rims with 107mm tires fit just fine. https://bricksafe.com/pages/Aurorasaurus/miscellaneous/ultimate-portal-hubs- ^ second photo thats in portrait and cant be resized small enough by bricksafe to display nicely without missing the point of the photo Awesome work @gyenesvi!

You can actually just print the ball a bit oversized and sand that down instead, but super glue and the Lego part might be stronger. Im going to try make these files printable today.

Aha, thats very clever, I like it. I hope it works. Will you share the files? I'd love to try 3d print it and test it out for you.

I want to dive head first into rc, straight into brushless. Mounting the motors to lego seems to be a solved problem to me, I've seen enough clever designs reading this thread occasionally that I'm sure it is possible. As for geek servos, is there a particularly good source for them or are they the same from every retailer? Thanks for you speedy reply!

Can you attach 5m half beams with cross axles to the arms next to the towball to stop the ball joints disconnecting, while still retaining a high steering angle? The lego planetary hubs do not allow you to keep a high steering angle if you do this. Aside from that this design looks fantastic, I especially like the ability to use 3 pins to hold the wheels in, but also 6 if you add 3 pins, I think thats a fantastic idea for supporting the old wheels but giving better strength to the new ones.