Appie

I made a stud.io file for the chassis, available here: https://www.dropbox.com/scl/fi/00ccqyyzdxi3hlswbzzjj/CompactCrawler.io?rlkey=rdpojjy2399r0bb1e6mgnzrb6&dl=0 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.

@AutoBacon 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.

Thanks. 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

Finished the chassis for that new axle I posted earlier, inspired by AutoBacon's work I wanted to keep the heavy parts of the model as low as I could, so I placed the battery box right above the drive shaft. As you can see I didn't manage to lower the front springs 1-2 studs. I might change the LBG part of the springs to yellow or something so I can hide it in the hood . The rear axle is pretty much a copy of AutoBacon's, except for the springs and I used another grey link on top (for symmetry with the front axle as the front has 2 as well to make sure an old style cv-joint for the steering won't pop out). Wheelbase is 18 studs. 3 studs shorter than my previous truck and if I am not mistaken 1 stud shorter than AutoBacon's pick-up truck (I was aiming for the same, but I misscalculated ). Gear reduction is 2.8:1. It climbs better than my previous truck. That truck had 4:1 reduction, but I think with the slippery obstacles and that with these tractor tyres, having some speed to get a running start on an obstacles helps. The balance is also far better with the lower center of gravity. Now to figure out what kind of body I want on it (will be something pick-up or Jeep-ish probably).

For this competition it was not, had to be 100% Lego. And actually, even if it wasn't a rule, I'd make it a rule for my own model. I like to keep my building solutions within the Lego options.

Yup, another builder noticed that while we were making the models (sadly he couldn't join for the video). Mahj's little truck from the video uses the same new CV-joints with that part and uses a 2x2 round tile with a hole in it to fix this rim touching problem (the extra surface also helps against the wobble you mention). As you can see in my picture I am using a 1/2 technic bush. For now at least, I'll probably change it to Mahj's solution. Ideally you want something of a 1/4 bush as a spacer to not rub the rim, but a tile is the closest we are going to get to that I think. As for the Mustang rims, I personally didn't notice a difference between them and the normal standard rim in terms of touching the above pictured part. Another solution would be this rim: https://www.bricklink.com/v2/catalog/catalogitem.page?P=6595#T=C With this rim the part does not touch the rim, but it's not a current rim, it was used in sets until 2006, but there is a 56mm tyre that would fit this (the red fire truck in the video uses these rims+tyres). Thanks, I love working on these small scales, like you said, you need to pick your parts carefully. For example, originally I removed that thin 7L liftarm at the bottom of the steering rack from your great design, then I noticed it functioned as a steering stop and prevented a little bit of the wheels bending outwards. So I put it back in I love such effective part usage.

Great to have you back. Gorgeous MOC!

What a great little buggy. I can see why you like that chassis, looks very clean and solid

Glad to hear it. Keep on MOC'ing, you make awesome stuff. Thank you very much. Here's another pic of it: It's driven by PU, 1 L-motor for drive and one L-motor for steering. This is basically what's under the bodywork: This was an early version, tweaked a few things since this picture. Mostly the 3 points where the axles are linked to the chassis (made the LBG 5L suspension arm in this picture parrallel to the 6L links so the suspension worked better). The reason I mounted the motors like this was so I could get some good gear reduction under it to crawl up obstacles. Yes, it's ackermann, like the original axle from Keymaker. Here are some close up shots of the axle. Keymaker could use 2x 5L thin liftarms for his axle, but for 9L I was a bit stumped for options. While making this axle I found out there's actually a thin 9L liftarm now, with 3 holes which could work for this setup, it's in the new Orient Express set. Since I didn't want to pay €5 for a single liftarm, I came up with another solution. The little rubber thing on top turned into the connector is to stop the connector from seperating (without it, I'd tear it apart when just removing the wheel). It adds a little bit more flex to the axle (wheels pointing outwards) than it probably would have with a 9L thin liftarm or Keymaker's 11 wide solution, but I had no other ideas or parts that were half a stud high and had a pinhole at the end. To prevent CV-joints from popping and have a little less flex on the axle, I started to build an axle with the new CV-joints similar to the one from this topic: My version so far of his axle: In order to make the axle sturdy where the one from AutoBacon used a 3rd party part, I needed 1 more stud towards the rear (where the red axle pops out, also the red axle is a place holder for the new CV-joint of which I ran out atm ) I want to figure out a way to lower the springs 1-2 studs. Not that I mind the solution from the original designer by just using springs, but I personally like to also have a "normal" alternative when I use that.

You sort of were. A few of us (I think I did it the most) took alot of inspiration from your Kraz 255 for you axle setup (and skid plates ). For fun I made it 9 wide instead of 11 wide (no dual drivetrain though), which made the car 15 studs wide, 2 below the allowed maximum. In hindsight not the best choice, I nicknamed my little car "the tumbler" after seeing the video where it's upside down quite a few times (and in the ranking as well) Originally both axles have steering, but one of the cv-joints on the rear axle kept popping so I adjusted it to a fixed axle before the video of the truck trial. Thought I'd mention that in case somebody wonders why the rear axle isn't steering in the video.

I made this last year and didn't get around to make a topic about it until now. A video of it transforming: The model weighs 1.6kg and most of that is on the front axle. I haven't been able yet to make a mechanism that will allow Optimus to lift himself without a "hand of god" Some more photo's The rope you see between the front wheels in the photo above is what makes the flaps with the headlights at the front besides the grill fold back when Optimus is standing, but flex (thanks to rubberbands) when the hands need to be folded back into the body when he's transforming into a truck. The little grey wheels you see at the rear wheels make the black rear wheels barely touch the ground, this helps the leg spread mechanism. Speaking of which, the clicking in the video comes from these 2 mini-LA's in the legs: They make Optimus spread his legs a little when he's standing. I thought that looks better than him simply having his legs straight when standing, but the gearratio is off. If I manage to make a mechanism for the legs that works in lifting the model on its own then I might be able to tackle this gearratio too. In case somebody wonders where I put the battery box, it's external Thanks for taking the time to read my topic, hope you enjoyed it. If you have any questions, feel free to ask.

Thanks guys! It does drive, just not very well when steering (and still not because it won't move, but because it isn't really moving in the direction you want it to move). None the less, I agree, even if it did work perfectly while steering, it's still 1-3km/h you can get out of such a model this size with Lego motors which is hardly worth the effort, but I had to try

Update october 2023: After abandoning this MOC about 7 years ago, I felt it was time to revisit it after years of brewing ideas to make this work. I am getting close to a full functional model, but not sure I can eliminate the last few issues completely. Currently the transformation works flawlessly, drive works, brake flaps work, steering wheel in the cab works, actual steering works somewhat, 360 turning works somewhat. The problems with steering is mainly in the arms for the wheels, the part above the wheel with the small turntables has too much flex, I need to tackle this while trying to keep the look of the arm as close to the source material as possible (and I already took some liberties there as you can see). It houses 2 XL for drive. There is 1 wheel at the front under the cockpit and one behind the exhaust each with their own XL. A concept was made to put the motor besides the wheel, like how the "real" model has an electro motor there, but it gave similar problems like the steering arm flex problems. 2 L- motors to steer these wheels 4 L-motors to steer the wheels at each arm 1 L-motor to act as a switch for "360" turning with 3 PF switches it inverts 1 drive motor, 1 steering arm motor at the rear and 1 at the front. I also use this setting to turn the wheels close to completely sideways for the transformation (I didn't do this in the picture above) 1 Servo for the brake flaps 2x (train) battery boxes. Also to be clear: the arms do not carry the weight of this model. I cheated, those 2 wheels for drive under the model+4 bogey wheels placed directly under the battery boxes carry the weight. One of my biggest mistakes from 8 years ago, was thinking Lego could handle this, so that was abondoned instantly for this. I also figured it would be nice to have a vehicle that's basically a tank, build like a tank, so it has about 40 5x7 frames, flip-flop beams and I tried to secure every panel into position. This makes it very heavy, but quite sturdy. Special note to https://www.eurobricks.com/forum/index.php?/profile/21067-hass-kabal/ He made a system bricks model of this batmobile long ago (2015) and I used some of his solutions, like the wheel arches on the side of the front arms, the steering wheel in the cab and I pretty much sized up his "electro" motors on the inside of the wheels. I hope to make a video of the whole thing within the next month, but no promises More pics will probably happen sooner than that. Original post from 8 years ago: Hardly finished anything on this model, but felt like sharing the progress so far anyway. Building this is the goal: Here's a video which shows various functions of the batmobile in the game: I am planning to add the following functions: -2x XL motor for 4WD (I expect the total weight to be about 3-4kg, so I reckon I could use their power. I am a little afraid of breaking gears/axles, so still have L motors as a backup plan. -2 servo motors which are going to provide 3 ways of steering: Normal drive with airflaps to assist steering (as seen in the video) 360 degree turn on the spot (unfortunately not in the video but it can do this) Battle tank mode with crab steering -2 M motors for the turret and opening the cockpit for Batman to get in (I expect to add that function anyway besides the 2 functions I want for the turret) -9 PF lights, among which 1 set for the afterburner in "normal drive mode" I wanted to built this model since Januari, I even briefly considered it for TC7, but Jim and I both agreed that this vehicle fails the "looks like a normal car in non-battle mode" Meanwhile some other people on Eurobricks had a crack at the model (click en clicker) I liked the first topic alot for the CGI pictures of the batmobile like this, because seeing all the details on a model that's mostly black ingame is kind of hard. The fact that Warner Bros cancelled the version of the game that came with a scale model of the batmobile didn't help either, luckily these pictures also help for getting the scale right in the MOC. The second topic is pretty nice for some of his brickbuild solutions. An area I am not too familiar with since I built mostly Technic and lack knowledge of normal Lego parts. Two things I don't like about the second model: the wheels are too small (or the model too big for the wheels), especially shows around the wheelarches, but the wheelarches on my model are too thick too, but not as much as this one I think. The other thing is that he cut and drilled some parts to fit the model. I like to find solutions within the Lego system, so modding is a big no-no for me. Anywho, time for some pictures. It isn't much (not even in time invested, since I just did a little every moment I had time for it), but at least I can copy-paste to the other side instantly, assuming I don't have to make adjustments (as if lol) The midsection is just for me to get a rough idea of how it will look (leaning on a BB so it won't fall over). So it's lacking details just about everywhere in that section. Wheels and stuff missing some details too, but I want to get a functional model first. Every wheel needed to have 3 things: drive, steering and lights. The real model has electro motors on each wheel, I briefly considered mounting a M or L motor on the side and have it drive the wheel, but getting it locked in place there wouldn't look right with the actual model (wire of the L motor basically going over the inner tire). One thing I haven't looked into though is making my own rims for the tires, I will see how this works out first. The wires for the lights have been in many places and this is just about the only place where they don't interfere with the steering and driving gears. Here you can also see the main reason why my wheelarch is too thick: I needed 2 studs to fit those functions above the wheel. I am afraid the structure holding the wheels proves to be too weak for the full model, so might have to reinforce that later on. XL motor's spot is up for the debate. It will probably end 2 studs lower. Gear ratio at the moment is 1:1 (I think), not sure which way I am going to go with that since the XL is known to break gears and axles Battle tank crab steering mode. My model won't make 360+ turns with the wheels, nor even 180 degrees for 2 reasons - 360+ I am not feeling because of the wires getting tangled up - 180 degrees isn't going to really work with the servo. I want to use the servo for snappy steering like the real thing. The liftarm for the steering is a stud closer to the middle of the car than i'd like, but this was the spot to at least get a 100-120 degree turn. One servo will function as a gearbox between the different driving modes while the other servo just steers. I chose this setup to be able to switch quickly between steering modes, just like in the game. Lights had to be used on this model. I am still looking for a way to get the lights to turn red when he enters battle mode, but I don't know where or how (open for suggestions). The reason the rear doesn't have 3 lights on the wheel (does ingame), is because these are rarely shown (battle mode only, and only with the wheel at an angle). In case you wonder about some angles in this model. Pretty early in the build I lost track of what's 100% clean so I just began testing stuff by fixing a liftarm on 1 side and lining it up with the hole I wanted to use on the other end. If I could spin an axle freely in this hole, I gave it the thumbs up, if not, back to looking for another solution. One funny spot on the model where there is pressure, is at the rear, thanks to the freaking 12L soft axles, which quite frankly aren't acting so soft! If the soft axles aren't locked into to place the triangle above the rear lights aren't pushed into the 5x7 panles on the top, they push them slightly in when they are connected Some panels are only fixed in 1 spot, to give them room to move slightly around another panel/axle/liftarm if needed. I noticed a little late that some photo's are a little blurry, sorry, will check it next time. Next up: the actual chassis.

Exactly this. The XL's could handle it fine, the wormgear could handle it fine, the 36T gear however, it bends, not just to the sides, but also (due to how that 36T is constructed) inwards. I have tried 2 gears, it still skips under the weight. Swapped to 40T gears, still skips. 28T look alot more solid, but due to them needing half a stud offset with the new wormgear, not ideal. Not to mention that 40T and 28T both mess with the desired gearratio. The current plan that might work is 2-3 (normal or large) LA's in each leg instead of a wormgear. Or perhaps some sort of pulley system. I don't think I can optimize the cabin transformation anymore besides making it slower at the motor (so the weight stays longer in the center of the model). Nor do I see much options for Optimus to lose some weight Actually, when he was a skeleton, he got up with L-motors instead of XL's in the legs, but the guy needs some bodywork and I tried to keep it light. @Dennis Bosman Oh yeah, the trailer. I was considering that (also to cheat with a sort of rope system hidden in the trailer )

So I haven't changed anything since my last post in october, but figured a video and some more photo's might be appreciated. As I pointed out earlier, the steering (combined with drive) only works so-so. This is due to the arms being able to bend (no idea how to fix this without completely diverting from the look of the game model), slack in the gears and the (small) difference in rpm between motors make it near impossible to get it "perfect". I am now considering to change the purpose of this model to more of a "demo" and remove drive and put it on a stand. Also when I would do that, I'd change to PU instead of PF since you can control the rpm and I could program the transformation instead of doing it manually like in this video. Not sure when I will get started on this, but here's some more pictures of the current model: Managed to squeeze in some computers (on both sides) for Batman to use: Detailed shot of the turret: Easy accessible battery boxes: Belly shot: In the belly shot, the little wheels at the front and rear of the chassis is what actually drives and steers the model, powered by an XL each and some gearreduction they manage. To see how these wheels are angled I have 2 visual indicators from above, at the front it's the steering wheel in the cockpit, at the rear however: It's this little DBG thing under the "shark bat fin". It's also victim to a little slack, so it's not perfect, but better than no visual indicator at all Thanks for reading. Another update might be some time down the road though.

What an awesome little nimble truck and the looks are perfect. Great video too. In march I got a truck trial with the LUG with 56mm tyres, so this is great inspiration for that, thanks.

Thanks, and yeah, that title is tad long I shortened it a bit

It's been a long time, but here's an actual update of the MOC. Updated the OP with this reply as well Update october 2023: After abandoning this MOC about 7 years ago, I felt it was time to revisit it after years of brewing ideas to make this work. I am getting close to a full functional model, but not sure I can eliminate the last few issues completely. Currently the transformation works flawlessly, drive works, brake flaps work, steering wheel in the cab works, actual steering works somewhat, 360 turning works somewhat. The problems with steering is mainly in the arms for the wheels, the part above the wheel with the small turntables has too much flex, I need to tackle this while trying to keep the look of the arm as close to the source material as possible (and I already took some liberties there as you can see). It houses 2 XL for drive. There is 1 wheel at the front under the cockpit and one behind the exhaust each with their own XL. A concept was made to put the motor besides the wheel, like how the "real" model has an electro motor there, but it gave similar problems like the steering arm flex problems. 2 L- motors to steer these wheels 4 L-motors to steer the wheels at each arm 1 L-motor to act as a switch for "360" turning with 3 PF switches it inverts 1 drive motor, 1 steering arm motor at the rear and 1 at the front. I also use this setting to turn the wheels close to completely sideways for the transformation (I didn't do this in the picture above) 1 Servo for the brake flaps 2x (train) battery boxes. Also to be clear: the arms do not carry the weight of this model. I cheated, those 2 wheels for drive under the model+4 bogey wheels placed directly under the battery boxes carry the weight. One of my biggest mistakes from 8 years ago, was thinking Lego could handle this, so that was abondoned instantly for this. I also figured it would be nice to have a vehicle that's basically a tank, build like a tank, so it has about 40 5x7 frames, flip-flop beams and I tried to secure every panel into position. This makes it very heavy, but quite sturdy. Special note to https://www.eurobricks.com/forum/index.php?/profile/21067-hass-kabal/ He made a system bricks model of this batmobile long ago (2015) and I used some of his solutions, like the wheel arches on the side of the front arms, the steering wheel in the cab and I pretty much sized up his "electro" motors on the inside of the wheels. I hope to make a video of the whole thing within the next month, but no promises More pics will probably happen sooner than that.

Seeing the mechanism in the original Claas set, then in Nico71's mini and now this one. Each a little different from each other, but each working very well. The whole concept of this mechanism still amazes me and how you figure this out to make it smaller is no small feat. Kudos.

Never have I considered this a statistic to watch. I can understand why you would though. I can also understand wanting to do well in a contest, but if lost? Oh well, had a good time building, the rest would have been a bonus to me. Personally, if I have nothing to add like a suggestion and my comment would boil down to "nice work", I am not sure how much value the reply has for the builder and I'd usually not reply. Me (or anybody else) not replying shouldn't stop the builder from giving updates though, sooner or later somebody is sure to chime in and share his/her thoughts on the build.

Jim has gone to great lengths as more competitions came to be on Eurobricks to have more and more detailed rules. He would still get questions about stuff already mentioned in the rules and he'd still answer them with amazing patience. Milan and Jim have also in the past made replies in topics for a contest that a model might not meet the criteria of the contest to prevent people from "wasting their time". Reading the comments from SaperPL just on this page, it really feels like it is even though he claims it's 50/50. He build an awesome model for the contest, one I'd be happy to build once I got some more free time on my hands. As long as you enjoyed designing it and are proud of it, does it really matter where it ends up in the ranking? Even if it didn't fall in the top 3, it's not like that hasn't happened before with great models in competitions here. Sure, you can disagree with the public voting or in this case the jury, but at the end of the day, is it worth getting this worked up over it and overanalyzing it? I'd hope not, but it seems you already made your choice.

Flex-system revival in modern times, nicely done. Perhaps a well-placed rubberband at the claw to make the default position open would remove the need of having to open it by hand? Will probably be a fine balance with the force needed for the claw mechanism, but since you're adjusting the gearing for it, it might work out for this too?

1. Accepting a red axle sticking out or not is up to you. I wouldn't, but I don't know how much alternatives are in that space. As I said, if you are up for making that connector axle moveable this would be an option to have it remote controlled. 2. Yeah, I edited that to my earlier reply, but you already started a reply it seems Could try to add a brace somewhere so the mini-LA or liftarms don't go further, but that's under assumption it doesn't need to go that far to reach the ground. If it needs more, than that 3L axle won't work ever and that would pretty much toss my whole moc-up out of the window with the current chassis. 3. Depends on the routing at the towbar imo. Straight to the center 2L connector, yeah that will fumble on those 3x5 liftarms. Guide them in a straight line from 2L thin blue liftarm, to towbar and then to 2L connector (or just stop at the straight to towbar) should be no problem. 4. As I said, you could make the angle slightly bigger than 90 degrees by having them face towards the red 1L liftarms in the towbar folded position. Other than that, you could mess a little bit with where you knot you ropes on the liftarms to get a 2L flip to a 1L flip. I don't have my Lego ready to build a prototype, hence the Studio image

Made a little moc-up in Studio. How about a rope through the blue thin 2L liftarms? Each side a seperate knot on the rope, which runs back to the towbar from underneath. Once it reaches the red 1L liftarms (for which I extended your pin with axle to a 3L pin with axle) it would flip the towbar. The thing could be slightly angled towards the red liftarms when the towbar is in resting position, should still flip if not too far angled. This should make it require no slack on the rope, since that part simply goes later in the mechanism and first when sliding back. Obviously, combined with a rubber band to make the folded position the default one. I am aware that in this moc-up that 8L red axle would be sticking out at the rear, but that construction of how you want to slide it out and brace it, is up to you. I'd need to build the whole thing to figure out the wiggle room I have or don't have in that area I'd even consider putting something else in place of the flip-flop beam if it would help, but I can't make that assesment at the moment. I am also aware this 3L axle on the #3 connector might collide with the liftarms connected to the mini-LA from the bed tilt, I don't know the wiggle room for it. It seems the bed is already on the floor before the mini-LA is fully extended?

Looks spot on and love the creative way you made the barcode truck without electronics. Can't wait for the full video.