[WIP (final tweaks)]Batman Arkham Knight Batmobile revisited 2023, close to fully functional

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You mentioned that the crab steering switch is going to need power and a lot of bracing to move the wheels out by force. I seem to remember on the game trailer that the wheels turned out and "drove" the arms out to the battle mode position. That would certainly reduce the torque on the arms. Just an idea.


:laugh: I wanted to bump this topic in about a week or so when I actually had something working again, but to answer the question: Great idea, this was originally the plan, but I didn't know how to implement it in that version. However since Barman, reverse engineer genius, figured out the Claas steering this is actually possible in my new set up. If all goes to plan it should look exactly like it does in the videogame, arms extending included (currently working on this). The solution I have for this transformation to look like the game is so stupid simple in combination with the Claas steering that I wondered why I didn't think of it sooner. Assuming it works of course, 99% sure it does.

So far I reworked the hubs for the wheels and gave them a fair amount of abuse to see how the held up compared to the old version. They passed the test with flying colours, but it did come at the cost of having the wheelarch 1 stud higher at a point where I didn't want it higher on the wheelarch, but oh well.

Also this image I got working, but I might put the L motor right on the wheel axle instead and hide the rear 3 studs of the L motor in the chassis. Not sure about this since it would show in battle mode, but I don't like the rubber on wheel solution completely, it's a "works 90% of the time" kind of thing, where the motor right on the drive axle works 100% and is more a solution that TLG would do.

Edited by Appie

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Figured it was time for a little long overdue update. This thing has been sitting on my desk basically for months. I just didn't feel like reworking the whole thing, but a new meeting in a couple of weeks meant new motivation to finish this thing so I got something new to show.

The front and rear arms are build again in a new sturdy style. Honestly, when I dismantled some of the old I wonder what I was thinking, it's so flimsy. These new parts passed what I now call the "carpet test". Sideways the construction does have a little bit of slack, but the L motor mounted on the side will compensate this. I apologize for these phone pics (again) in advance. Not all details are present yet on these arms, some will be made with system bricks (like the slope above the front wheels) for others (like black bionicle teeth) I need to place a bricklink order. Figured it should first be functional before I go for details.



Compared to the old versions where I had to consider the driving axle and steering mechanism in the arms that problem went out the window with these versions. L motor mounted on the side of the wheels would handle the drive as well as form the base as a mounting point for the steering, this meant I had a chance to play with these arms a bit more. Something I couldn't do in the original version: extension of the arms.



I think the rear part behind the wheels of this arm is the only part that survived from the first version :sweet:

To tell you the truth some of my design choices I liked more on the old version (like the angle of the panel in front of the rear wheels being sharper), but overall I think these are better.

I tried to mimic the actual extension of the arms in the videogame.



Some compromises had to be made to ensure no wobbly stuff. Besides trying to mimic the real extension this is actually a crucial part in aligning the wheels after the transformation (at least, that's what I expect the model to do).


The red is basically my arm stunt double. This model will use Barman's Claas concept, except I am making one on each side of the vehicle for the zero degree turn feature instead of the Claas counter steering option. This whole steering mechanism will be on a sled (for lack of a better word) and move outwards after the arms extend forward (this part I still need to make, but the arms have already have their attachement points for this system). Obviously the picture above is a very rough version, I decided the battery boxes will be at the very bottom sideways (4 studs high) besides Batman's seat basically, this gives me room for easy access to BB's and also I can hook up a liftarm to the centre of the L motor if I wanted and carry it over the BB's.

Of course I first made Barman's Claas concept from his LDD to play with this and see what issues arise.


As you can see I messed around with bigger steering angles. At the moment the steering angle on the Batmobile will be about 45 degrees, which is not as far as the real thing, but looks like the best I can do atm.

Anybody want some old wobbly Batmobile arms?



Tomorrow I will try and figure out a concept to drive the arm extension.

Edited by Appie

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Umm.... I'd take these arms I guess! :D

Good luck - doesn't matter how many times you screw up, you still get it on the first try eventually :D


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Those are just some images I found in another topic on this forum (link in first post of this topic). I really like them for seeing details better and to use for scale reference. Yesterday I found out that my chassis is actually 2 studs too short in width. Dumb mistake, but I am happy, I can really use the space.

And krisandkris12 that image isn't far from the truth, some systems are already on their 5th 'batarang' or something :D

Edited by Appie

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Well time for another update. Extension mechanism is about 60% done, first I had to tackle another part of the model: the steering setup


Yes this looks super flimsy, but this is basically the guts of the mechanism without any bracing. It's pretty much how I test stuff before building a structure around it. Funny thing with this was: I didn't need the arms to extend to align the wheels. :cry_happy: And yet I do to reduce friction on the transformation, though the wheels don't turn nearly as much as I would have liked, they still turn somewhat. I decided to leave the extension in, because the real thing had it and I liked it. This meant I had to readjust the whole concept for the liftarm construction I had in my mind to get proper angles on normal and tank mode for the wheels. I got as close as I could I think. They are straight in normal mode and a few degrees off in battle mode, but any adjustment I try to make to this means it goes off elsewhere. The angle of steering is smaller than I would have liked, but this is the best I could do without interfering with the wheels or front of the model (which I am already invading a little), I'd say it's about 35 degrees.

Anyway about the image above, you basically see an adjusted version of the Barman's Claas concept. This setup will be on the other side of the model as well. I need the concept twice for zero degree turning. The centre with the 3x5 liftarm will move with a servo (9L axle at the rear is about where it will be). I am looking for feedback on the actual steering though. The part that steers will slide one stud to each side of the vehicle after transformation, so the mechanism has the slide along with the rest. As it stands I have 3 options:

- Use the frictionless 8T gear in combination with one servo to steer both sides of the vehicle.

pro's: one servo used. I am already using 2 for the mode switching on each side at the rear, so this would be #3

cons: gears in a system that already has slack. Besides using some of Lipko's double bracing ideas from his cool Telehandler, this can't be totally avoided, but gears would make it alot worse than it has to be.

- Use a wormgear (these slide just as well as frictionless 8T gears) with 24T gear + M/L motor

pro's: less gears used than the first option

cons: I'd miss snappy turning of the wheels that a servo would provide

- Use 2 servo's

pro's: accurate and snappy turning, minimal slack

cons: 2 freaking servo's. I got them, but that's not the point. I kinda find it the lazy way out, but I can't come up with another option that might be better.

If anybody has a 4th or 5th option I am all ears. Leaning to #3 atm.


4th option: use a liftarm that can slide and is also attached to a gearrack (fixed) which will turn a bevel gear at the base.


After recieving some feedback today from some dutch Technic heads (Ludo Visser and Jovel) I decided to go for the double servo. They pointed out one servo might struggle with the weight of this model and gears aren't a favorite for a model this size. Thanks guys. Currently building the whole sliding carriage with this mechanism on it and 2 servo's.

Edited by Appie

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Nope, learned a lot from this failure though, which was a good lesson for how I approached later MOCs. 

I might revisit this MOC in the future if I feel confident enough I can get it to work. 


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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

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 :wink: More pics will probably happen sooner than that.

Edited by Appie

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As one who spent many hours playing the game, I find this build both fascinating and immensely appealing! Please keep at it and keep us updated.

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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 :laugh:

Thanks for reading. Another update might be some time down the road though.

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No superlative can describe what you have created!
I actually think it's quite good that it doesn't drive. As TLG's motors would be way too weak to move the Batmobile adequately!:wink:

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Thanks guys!

It does drive, just not very well when steering :grin:(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 :sweet:

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