Help with finding solutions for getting an AT-AT walk cycle like in the movies.

[bruh]

Just found this topic. Very interesting!

If you cut up part of a rubber balloon, and stretch it over the bottom of the foot, that will help with grip so the foot doesn't slip when walking.

[Nelson]

I'm still ironing out some issues with the mechanics, but thought I'd share this building technique using bars and round plates. It doesn't look as nice (or as screen-accurate) as the inverted tile pieces I had cladding the legs previously, but it's seriously tough. If you use this technique, get it right the first time because it's quite difficult to deconstruct!

 

 

[Toastie]

23 minutes ago, Nelson said:

but it's seriously tough

Wow! I am not into AT-AT's at all (but follow this thread with close attention), however, this is a very cool technique making strong connections! Have to remember that - well, it is copied into my "this is how you do it right" folder!

Thank you very much for sharing!

Best
Thorsten 

[2GodBDGlory]

That is cool!

And again, I love the perseverance displayed in this thread

[Nelson]

Here's the latest. It's been torturously frustrating trying out several time-consuming concepts only to discover the model runs worse than before. Each iteration takes most of a day to redesign, tear down, rebuild, and test. I'd say this version is about as good as the last video I posted. It's really tricky getting the legs to not interfere with each other as they flex from their own weight. I'm going to take a few weeks off and see if diffuse thinking offers any revelations.

Abridged-Terrain Awkward-Transport

 

Edited Friday at 02:44 PM by Nelson

[Nelson]

So much for taking time off. I woke up with a few ideas to try out. I was perusing BrickLink yesterday and ran across part #28974. (https://www.bricklink.com/v2/catalog/catalogitem.page?P=28974#T=C)

A quick test with a minifig backpack confirmed this is a great part to shim various areas where you need just the tiniest bit of spacing. For my model, it will help get a touch more lift height in the legs. Obviously, I won't use the brown minifig backpack shown in the photo once I get the more appropriate parts, but you get the idea. There was just a touch of un-utilized gap at the peak of the leg lift cycle, but it was too small to add even a thin bushing. Now the crank can get that little extra lift it was missing before. That tiny shim gains me about 2/3 stud in height once the distance is amplified at the end of the liftarm raising the leg.

 

[Toastie]

1 hour ago, Nelson said:

great part to shim various areas where you need just the tiniest bit of spacing

Great!

When I ran into similar issues (on much, much simpler builds!) I used the #42446 bracket - simply because I have a couple of those.

I have to admit though that I usually use very thin 5 mm id metal washers and stack them up till it fits. Yeah, I am on the dark side, I know ... you can also make such washers by drilling 5 mm holes into other thin LEGO parts such as panels and so on ...

Actually, I also know this "need to take a few weeks break" feeling very well! And regularly it just turns out to shrink to one night. Not so much of a surprise as time is relative. A night of good sleep (at warp speed) seems to be the equivalent of a few weeks of trying harder (at snail speed). It also seems that seriously threatening the deep areas of the brain with "taking a few weeks off" gets things rolling much faster ;)

Keep up the good and creative work! Cross my fingers!

Best
Thorsten   

[Nelson]

I'm trying my best to keep the model pure, using only genuine Lego parts that are "currently" available. I'd like to eventually sell the instructions on various platforms and that usually means not using non-Lego or out of production parts.

[Toastie]

1 hour ago, Nelson said:

I'd like to eventually sell the instructions on various platforms and that usually means not using non-Lego or out of production parts.

Absolutely! And I bet there will be quite a number of people who will be interested/purchasing! That would include me ;)

How about a little cheating only during the (very complex) construction process, consisting, as you said, of many teardowns and new starts, modifications (be it only a fraction of a plate height), and so on? Maybe you could get more swiftly to a "test rig" instead of browsing BL and other LEGO resources? I'd even go to using screws, if things need to be held in place, but so far there was no way of doing it in pure LEGO world. And then, when the result is satisfactory or considered a step forward, refining it to get it "pure"?

I do that in research a lot. One example: Ultra-high vacuum (= ultra clean) environments we are monitoring on weird industrial sites do never tolerate any kind of glue, plastics, grease, etc. However in the lab, when we are “constructing” ("figuring out by trial and error" is a much better phrase) these metrology machines, 3D printed plastic parts are all over the place, superglue here and there ... Once the thing seems to do what it is supposed to do, we go to our machine shop and have it made of stainless steel, millable ceramics, and so on.

Well, just my odd and most probably totally stupid ideas.

Best
Thorsten

  

[Nelson]

I did do a bit of "cheating" early on in development, using non-lego springs, rubber bands, etc. But at this point, I'm down to two general model concepts (currently working with concept #2), so I typically start with a test mechanism that's all Lego. It's just one leg or quadrant stuck on a 19x11-stud technique panel (https://www.bricklink.com/v2/catalog/catalogitem.page?P=39369#T=C). It's kind of a pegboard where I can try out different geometries and timing. Unfortunately at this point, there's no replacement for actually putting it all together and firing it up. The concept is fairly proven, but it's really touchy in the overall build. IE: Last night I found out that kicking the timing of the rear legs forward one gear tooth caused total failure of the entire system! I admit that I still don't fully understand what makes one model work while another almost identical one fails even though I've been at this over four years now! Heck, NASA sent men to the moon only eight years after Kennedy's speech!

Edited Friday at 10:22 PM by Nelson

[Toastie]

23 minutes ago, Nelson said:

Heck, NASA sent men to the moon only eight years after Kennedy's speech!

True.

But: "Moving as in the movies" AT-ATs don't exist in 2026. I may be wrong. But for sure not in LEGO universe. NASA had uncountable men and women working on the Apollo mission; according to Googles AI 400.000. As far as I am aware, you guys are down to two individuals, at least in this EB thread. So it may require some ... years. I truly believe it is worth the effort - as long as you have some sort of fun - or energy supply. 

Personally, I love this project.

All the best
Thorsten  

[BrickBear]

Looks like you’re getting on a treat Nelson! I’m away from my Lego at the moment (working on a graphic novel) but I whipped up this brainwave I had in Stud.Io. I traced a line of how the at-at’s leg moved from some footage and figured out this shape of cam is about right for the forward and lifting motion. My initial problem was I was looking at the current unbending, single lift arm legs of my AT-AT and thinking the point of the knee was equivalent to the point of the foot

This is the path the pin hole where the knee would be takes with the current setup, mind it was a little confusing as I took photos of my computer at different angles so it might be better, might be worse in reality, I’ll see if I can redo it with snipping tool instead.

Here is the path an at-at walk takes at the knee and foot: the red line above is the current path of my actual physical walker. I would say I’m much closer with the brick link version. 

 

30 minutes ago, Toastie said:

True.

But: "Moving as in the movies" AT-ATs don't exist in 2026. I may be wrong. But for sure not in LEGO universe. NASA had uncountable men and women working on the Apollo mission; according to Googles AI 400.000. As far as I am aware, you guys are down to two individuals, at least in this EB thread. So it may require some ... years. I truly believe it is worth the effort - as long as you have some sort of fun - or energy supply. 

Personally, I love this project.

All the best
Thorsten  

I can’t speak for Nelson but I can say I am nothing if not tenacious. And just think we’ll be making history, nobody has done this before, unless you count JK brickwork’s gingerbread AT-AT that has the right cycle but is stuck in place (the mechanism is in the ground). If successful I’m going to make a journal from the perspective of a kuat drive yards engineer with all sorts of drawings and such with instructions too if life finds me time for it. 

[Toastie]

12 minutes ago, BrickBear said:

And just think we’ll be making history

Yes, you will. 

I love this. Making instructions, selling them (why not), writing a book, whatever serves as documentation. After all, this effort is materializing a - thing - from a galaxy far, far away - in this world, hey, even more focused, in LEGO world. The more you spatially focus, the less well-defined is time or energy ... OK, that is just nerd talk. But it is true :D So far.

I am watching the progress here in awe.

All the best for both of you, make it - in one way or the other - just happen.
Thorsten    

[Nelson]

@BrickBear I'm not quite following your post, but it seems like you feel your current leg motion isn't as close to the ideal line as you'd like. I'll look forward to seeing updates when you get back on the project! I love how differently we think about the same challenge and how we utilize different tools to assist us in our quest. I imagine Lord Vader and General Veers hanging out in a conference room hashing out the AT-AT's design. Vader is pushing the intimidation features of the vehicle while Veers is concerned about its fuel economy.

I'm "satisfied" with the gate of the version in the video below. This concept design will always have a bit of shuffle from the feet on the ground. It's just the way the geometry works. I've minified it as much as possible. I could go back to concept #1 (and may someday), but I think #2 is more stable, robust, predictable, and will be more conducive to creating instructions for laypeople to build.

I've got clearance between the toes now! (Barely!) No hang ups. That may change as weight is added. I've attached the aesthetic "shoulder" pieces and love how the look is coming together. (I'll worry about articulating the upper legs later.) I'm going to try to get the side cladding on this weekend and see how it handles that weight.

@BrickBear One issue I've noticed in this thread is that we don't have adequate language to describe our model's mechanical features. I created this image and will use the terms shown in it moving forward.

And here's the latest video: