gyenesvi

Very nice design, I like the coloring and the minimalist paneling with a few big pieces that just fit nice. The drivetrain also looks simple and efficient, I like how it incorporates planetary hubs. In the steerig system, do the liftarms that connect the two steering racks pivot around some point that makes the second axle rotate less?

That’s a pretty cool looking truck, I like the parts usage especially on the cab. The steering solution at the front axle is interestingly simple, the way it pushes up the whole steering shaft! :)

Put it on the charger and leave it on for 3-4 hours, after a while it should wake up.

I surely find that as an adult I have higher expectations than I had as a child :) But the charm of Technic is not gone, there are many more mechanisms that I understand now and can try to replicate with lego parts. As long as I can have the required parts I can put up with the large amount of not so functional cars, and that's where I am not completely satisfied with lego. Instead of comparing it to how it was before, I usually contemplate about what it could be or become as a system now or in the future, and that's where I am not sure about the trends of the Technic line. I have already discussed this topic in other threads, about long missing generic/structural parts (such as length and color variations), that actually prevent me from building stuff I want, and these are not inherent limitations of the material or manufacturing process. Another trend I observed and no sure I like so much is some part design principles. I find that many special purpose parts are designed such that they try to be somewhat multipurpose, I guess for reusability, for example wheel hubs (like planetary and portal hubs). They are made such that they can be used both in steered and non-steered suspension (while older/simpler hubs differentiated steered and non-steered variants). I understand the optimization behind it, but I find that as a consequence, the resulting parts are actually not really good for either purpose, so we end up with suboptimal structures because of some cost saving. Similarly, about stock sets, my only real complaint is if a set misses obvious opportunities to evolve the technical part selection, like that RWD Raptor or the trial Zetros. If they come out with a large scale trial truck, it better also focus on the trial aspects such as suspension, besides the looks and branding. I wish TLG lived up to the "build for real" slogan in these cases. I understand what makes these sets sell, but it would be great if at the same time experienced builders would also get what they want under the hood.

I see that this has already been decided, and it's fine for me because of the thin line between the two regarding parts and electronics (though I tend to agree with @Toastie that Mindstorms is more about the programming, less about the building, while Technic is the other way round), and because I am interested in Mindstorms but I rarely get to visit the forum.. I also wanted to note that I'd support the idea of moving contest related entries to a single subforum (contests don't overlap in time so one is enough), that way we could post non-contest related builds even during contests without worrying about being pushed out quickly from the first page by the contest entries. It would also be easier to find contest related stuff all in one place.

Good to hear, glad you didn't regret it :)

Thanks, I guessed that such ordinary portals would not fit into a lego rim of that scale. Is that right? Is that why you are not using a lego rim? It's a really nice build, it's a pity that the steering angle is not very good with that CV joint, and a 1:3 reduction would not fit in there..

Indeed, that looks absolutely good, even compared to your version 1! I love the wheels too. I wonder how you built the portals in such a small space. Can you show zoomed in pictures of that?

The driveshaft angle looks better to me now! I guess that’s a good strategy. You’ll have most of the weight low anyway, and that’s what really counts for tipping over. The cab won’t get that heavy I guess.

Does that Jeep have RWD/4WD switch? To me it seems from the instructions that it has a regular drivetrain with a central differential.

Could be pretty useful even though it has only two ports, if it wasn't soooo expensive. I have already designed (virtually) a small car chassis where this would fit really nice.. But haven't yet convinced myself to actually buy it.

Not the camber, rather it would improve the caster angle at the front, it would become neutral, not negative.

What I meant is that the overall height and clearances would look the same, it's just that the driveshaft would come out from the chassis lower, and the ball joints going to the axles would be laid out horizontally. You could put the panhard rod to the very end of the axle, there you have a lot of space, and also it does its job better there as there it takes less force to hold the axle in place.

Oh, sorry, my bad, I totally misread that. I guess then, as you write, it's due to the custom built portal hubs not being that strong. I really wish the Lego portal hubs were more useful and there would be no need for custom building them. They are so bad with the steering geometry.. which causes problems with the wheel hitting everything nearby. Wow, that will be quite high and steeply angled when not compressed. Is that going to be symmetric in the front, with similarly high negative caster? That could also cause problems with the steering geometry. Furthermore, what's strange for me in your build is that the driveshaft is routed very high in the chassis. The axle builds are interesting in that the driveshaft comes in quite high, and I thought the purpose is that that way you could allow the ball joints to sit horizontally, while still having enough clearance. Why did you need to put the ball part of the ball joint so high in the chassis end? Was it not possible to place it to the very bottom of the chassis? That way the whole driveshaft could be horizontal, which could eliminate the negative caster in the front. As for the panhard rod, its geometry matters a lot when trying to avoid sideways movement. You need to place it in such a way that is is horizontal when the suspension is compressed halfways, in order to minimize side movement. Also, the longer the rod the better, going from one side to the other. You can actually build a longer one from towball arms connected by a liftarm.

Hmm, that's even a bit more expensive than the $52 from the US.. I expected these motors for about half the price, or maybe at most 30€.

I have been wanting to buy this small motor for quite some time, and could not find it on lego.com, thanks for that link @1gor. Interestingly, it seems to be possible to buy only in the US, if I pick another country, it does not put out any price. Ordering from the US, if it even works, would cost $52 with shipping, which is quite a lot though.. Did you buy yours through a dealer? I also tried finding a dealer in Hungary, found one, but it does not seem to be selling to individuals, not even the whole Spike Essential set, not to mention parts of it. Wonder if these will ever be released in any technic set. It would be useful for quite a few tasks, but the voltage does suggest that it won't really officially be working with the Technic Hub. Even the description on lego.com says that it supports the large (mindstorms) and the small (spike essential) hubs, both rechargeables, but does not mention the medium (regular Technic) one.

This thing is getting huge, especially in the middle! Are you sure you are not loosing the ground clearance provided by the portal axles? It seems to be quite low in the middle. About the negative caster, as you are using the ball joint to mount the front axle as well, that can only result in a negative caster at the front, unless you mount it horizontally when the springs are fully uncompressed, and go up from there, but that’s again bad for ground clearance. This is why I don’t use it at the front, I think it’s mainly good for the rear axle (maybe for an SUV type car, but not for a trial truck).

I think first you need to sort out the geometry of the axle/links without springs or any dampening. A proper design should not move sideways or let the axle tilt forward/backward. You can achieve that in various ways, but in general you need to restrict all unwanted directions of movement. For example, in your image with the 4 link setup, the four links are parallel, and hence it does not provide any restriction for sideways movement. In order to achieve that, either the links must be triangulated, or alternatively the chassis end of the links could be rotating on a pin, not a ball-joint, only allowing minimal movement sideways (for that it must be built from a regular liftarm and a towball socket liftarm or A-arm, which also has the advantage that you can simply attach a spring to the link itself). Another alternative is to use a panhard rod to prevent sideways movement. One more trick that is often used on rear axles in smaller scale lego builds is to have the driveshaft provide one more fixed point, by removing the U-joint at the axle end, and that way limiting its movement (this is similar to what a ball-joint does, and was actually used in cars of this era, it was called torque-tube suspension if I recall the name properly). For the steering, if it’s linkage based, it comes down to proper geometry again. To minimize bump steer, the longer the steering link, the better, and it should be positioned such that the link should be horizontal when the suspension is halfway compressed. That way, the divergence from horizontal will be as small as possible in all positions, and will result in small ‘lengh reduction’, and hence unwanted steering. In case of rack based steering, if you are using two CV joints to route the steering to the axle, as then it should be okayish, true that as the axle tilts, in theory it would effect the steering, but the wobbliness of the joints should actually accomodate the amount of rotation, so it should be negligable. For dampening of this type of car’s suspension, I’d try either flex axles (pre-loaded in a curved shape), or torsion bars (maybe with a push-rod like extension). These could give it some sort of authenticity. You maybe want to check out my Toyota FJ40 alternate of the Ford Raptor, it has a linkage based steering behind the axle with unnoticeable bump steer, and also a fake engine above it (but it uses springs). It has links both behind and in front of the axle and the front ones are fixed to the chassis, that prevents sideways movement. I have other builds on my rebrickable for example with triangulated rear suspension.

That's a cool mechanism, is something like that used in real life? Does it keep the platform horizontal, or just approximately? What's the function of the rubber bands? Are they for stability?

Yeah, and it's 3x the price. Since I am not using it for anything else, that's not the first option I'd like to try. That's what I tried and that's not working. I don't play any such games, but I tried with the config app advised by the gamepad's documentation, and that is working fine, all events from buttons and joys are received. According to the documentation of the gamepad, it has 3 modes, 2 for Android, and 1 for iOS. I set it to the iOS mode. (I tried in the other two modes as well, but then even the official config app is not working, it detects that it's in the wrong mode). I might try and download some game for testing. Can you suggest one that is free and can try this easily?

Thanks for the link, this is what I was thinking too, just could not find it on Ali. The thing is that I haven't found one with ~85 mm outer diameter that has a thread pattern I really like; so far this is the best looking. Maybe I'll try them out.

I remember this part, I may even have it somewhere in my parents' house, but I think from another set. I guess in most cases it can be, though there is one difference which may be important in some use cases. The 14 tooth gear's teeth are not symmetric wrt rotation with 90 degrees; either one tooth or one hole between two teeth will fall to the horizontal/vertical line depending on rotation. That can be useful, because with them you can create a mesh where both the incoming and outgoing axles are exactly aligned to 90 degrees, while you cannot do this with the 12 tooth gears because they are symmetric wrt 90 degree rotation, so the axle of one of the two gears in a mesh will never be exactly aligned to 90 degrees. I hope this is understandable, I cannot explain this better; in case it's not, just try it and you'll see! :)

So I have been trying to figure out which gamepads could possibly work with iPhone/iPad and are also easily accessible here, and I found the iPega 9129 that I like (for about $22). So I jumped on it and bought one (it can be taken back to the store within 14 days if it does not work). The gamepad connects to my iOS devices fine, and it has its own config app, which I downloaded, and after setting the gamepad to iOS mode, it is able to register the button hits and the joystick moves in its own app in test mode. However, when I fire up the BrickController2 app, it does not register any joystick movement or button clicks. Any ideas why this is @imurvai? Is it possible that your app is using a different communication API than its own app? Are there multiple ways to do this on iOS? As far as I understand, after successfully pairing the gamepad with the phone, I don't need to do any further configuration in the BrickController2 app, it should just be able to register events on the Controller tester screen, right? BTW, I have tried this with 3 devices (two with iOS version 12.5, and one with 15.3), connecting the gamepad works on all devices, but BrickController2 does not register events on any of them.

Nice buggy, I like the way the front shock absorbers are built into the A-arms. But the caster angle seems a bit too much for me, I am not sure if that much has some mechanical disadvantages, for example, as the wheel moves up, it also moves back a lot, isn't that a problem? What are the 85mm tires you are using? Do they fit the rim well?

I saw such controllers, and that seemed like a straightforward idea, but unfortunately I am using my phone's camera for filming (mounted on a gimbal), and so need to use my tablet for control, and this approach does not work with a tablet. May be useful though when I am not filming. I saw these ones too, but did not really like them. I prefer more compact stuff. Anyway, I think the easiest would be just to put down the tablet somewhere.. Or into a backpack. That's also a reason why turning off the screen would be preferred, as that would prevent accidental touches that may stop the app from working. Indeed, that would be the plan!