Ngoc Nguyen Posted April 7 Posted April 7 (edited) Earlier this year I did the Mercedes Benz Zetros 2733 6x6, which was partly based on the preliminary design of the 42129, because I wasn't quite keen on doing the mini replica for the official 42129. But then I gave it a try, and discovered that the linked differential lock is actually a nice problem to tackle, and solving it can help with the design of a mini 42177, so I started doing the full mini 42129. The front half and the cabin are taken directly from the 2733 so there's nothing new there. The only new thing is the design for the rear axle, which is only possible thanks to the new perpendicular 7L liftarm. Here arises a new challenge. The axle that transmit the differential lock has to be trasmitted perpendicularly, and within the space constraint, it can only be done with a pair of 12 gears. That means the red axle rotates 45 degrees. But the axle that turn the central differential lock has to be at an upright angle. Therefore I used the new gear selector drum from the 42159 Yamaha motorbike to create a 45 degree offset on the same axle. Also because of the space constraint in the body length, I have to use the 2L Driving Ring also from the big motorbike. The rest of the model is pretty much the same as that of the 2733 6x6, so there''s nothing new to present. Here are the function sheets, which are also modified versions of those of the 2733 6x6. I've just created an Instagram channel for my creations, so I'd appreciate it if you can support it. https://www.instagram.com/ngoc.brickcorner/ Free instruction: https://reb.li/m/217171 Edited August 5 by Ngoc Nguyen Quote
Aurorasaurus Posted April 7 Posted April 7 I saw this on rebrickable today, its quite clever! But to me, the back braces from the top of the cab down to the bed feel slightly too long. Other than that I like it a lot. Quote
Paul B Technic Posted April 7 Posted April 7 (edited) I am a big fan of this, you have done really well to "shrink" this. Edited April 7 by Paul B Technic Quote
Ngoc Nguyen Posted April 7 Author Posted April 7 (edited) 1 hour ago, Aurorasaurus said: I saw this on rebrickable today, its quite clever! But to me, the back braces from the top of the cab down to the bed feel slightly too long. Other than that I like it a lot. It is only slightly further back because of the connection point. 26 minutes ago, Paul B Technic said: I am a big fan of this, you have done really well to "shrink" this. Thanks for the support! Edited April 7 by Ngoc Nguyen Quote
Jundis Posted April 7 Posted April 7 Again fantastic work of shrinking! Did you already started doing a physical model of it? :-) Quote
Ngoc Nguyen Posted April 7 Author Posted April 7 12 minutes ago, Jundis said: Again fantastic work of shrinking! Did you already started doing a physical model of it? :-) I had a physical model but it was for the 2733. At first I intended to order parts for this, but then since this model reused the whole front half of the 2733, I decided not to do it. I don't want to build anything twice, and the parts are not cheap. I only test build the linked differential separately and it worked, so that should be enough. Quote
N1K0L4 Posted April 7 Posted April 7 Looks great! Only thing I would add is a exhaust behind the cabin, part 65571 would fit well. What shrinking factor did you use? Also do you think there's enough space to motorize it with BuWizz micro motors? Quote
gyenesvi Posted April 8 Posted April 8 Very nice looking and clean model! I like the diff locking rear axle, even though the construction is probably not strong enough for motorization, it works for a manual model. Is the front axle pendular only without springs? Quote
sondh Posted April 8 Posted April 8 Looks great anh! Ordering extra parts for the weekend project Quote
Ngoc Nguyen Posted April 8 Author Posted April 8 10 hours ago, N1K0L4 said: Looks great! Only thing I would add is a exhaust behind the cabin, part 65571 would fit well. What shrinking factor did you use? Also do you think there's enough space to motorize it with BuWizz micro motors? Thanks for the compliment! As I said in the presentation, this creation is more of an afterthought after I did the 2733, so I just want to get the basics done and move on from it If you notice you can see that the rear mud flaps are missing as well. I just cant be bothered... As for the shrinking factor, I didn't scale directly from the official 42129, as some of its proportions are not correct to scale. Instead I worked directly from the blueprint of the Zetros. As for motorization, yes it is possible to motorize at least the drive and steer. The bottom white axle with frictionless pin is the drive axle. The two axles above it are the steer axles. You can refer to the function strip out image in the original post to see how they are connected. If you replace the back 3x7 panels with some other parts that allow the axle to go out in the back you can hook some motors to it. In case you want to hide all the motors and buwizz hooked to the back, you can build this alternate version instead. It is based on an actual trial truck version of Zetros called Zetros High Altitude. There's no tapered panels in blue or dark blue, while medium blue and dark azure don't really fit, so I went for the ones in turquoise from 42117. 14 hours ago, Timorzelorzworz said: Really great! Thank you! 4 hours ago, gyenesvi said: Very nice looking and clean model! I like the diff locking rear axle, even though the construction is probably not strong enough for motorization, it works for a manual model. Is the front axle pendular only without springs? Thanks for the compliments! The front axle is indeed pendular without springs, but it still has some elastic suspensions thanks to the rubber connectors. 1 hour ago, sondh said: Looks great anh! Ordering extra parts for the weekend project Thank you! Quote
LEGO Train 12 Volts Posted April 9 Posted April 9 Great model and nice functionality of the differential lock The exploded view of the internal mechanical part is useful! Quote
Ngoc Nguyen Posted April 11 Author Posted April 11 On 4/10/2025 at 3:07 AM, LEGO Train 12 Volts said: Great model and nice functionality of the differential lock The exploded view of the internal mechanical part is useful! Thank you! Technic is all about the cool function, so the exploded view is a must. Quote
Ngoc Nguyen Posted April 12 Author Posted April 12 The possibility of RC mini 42129 suddenly piqued my curiosity. Not sure if there is much interest here in that thing. If there is sufficient interest I might make a free RC version based on the High Altitude version. The idea is to hide all the motors, RC receiver, and battery box in the back. Quote
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