Subject:
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Re: has anyone made an at-at out of lego?
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Newsgroups:
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lugnet.starwars
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Date:
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Fri, 9 Jul 1999 18:57:49 GMT
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Viewed:
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1000 times
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In lugnet.starwars, Shaun Sullivan writes:
>
> 3) The legs are two bumps across, as viewed from the front. I haven't
> finalized the height yet, as I'll want the entire model finished to
> adjust for scaling. I've thought about what it would take to gear the
> legs and make it walk. First of all, there would have to be some
> technic-type beam supports in the legs themselves. THe feet are large
> and heavy enough that they will fall off otherwise: not too hard to
> implement. As for the actual drive system, I was envisioning a single
> compound mechanism that would swing the leg forward at the hip joint
> while bending the knee, and then straighten the knee, then swing the hip
> back. That way, the leg would move forward, plant the foot, and pull
> the body ahead slightly. I pictured the ankle and toe flaps as being
> free, so that they always swing down due to gravity as the leg moves.
> By doing this with all four legs (maybe in a 1-3-2-4 pattern, with front
> legs being 1 & 2, rear being 3 & 4, numbered clockwise), I think it
> could be made to walk ... slowly :) Now, for the gearing, I figured
> that with some scotch-yoke machanisms for the forward/backward swinging,
> and some cam system for the timing of the knee bend, and of course tons
> of gear reduction and wormgearing to get the torque up ... well, I think
> it's possible, though intimidating. One major design flaw I can
> envision is the transmission between the hip region, which is fairly
> straightforward, and the knee, which is well removed by a long thin
> leg. Unless there are LEGO timing belt I'm not familiar with, I'm
> guessing a belt would slip - maybe the timing chain from the likes of
> 8880? If not, then a ridiculously long gear trin might suffice, but I'd
> be worried about the combined tooth stresses deforming the pieces, or
> just ripping the assembly apart: that a long moment arm with a
> relatively large weight at the end. Plus, the sum slack in all those
> gears could make for a pretty loose system ... In any case, it would
> definitely be more easily done if the minifig amenities were done away
> with, and it was primarily a Mindstroms model only.
Have you considered trying the flex system for the knee joints? I kinda have
an idea, lemme try to explain it. It would involve either a cam or a wheel to
pull the leg back when it begins a step and straighten it out as it finishes.
Do you think that might work?
Jeff
- "This is definitely *not* an ordinary spell!"
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Message is in Reply To:
 | | Re: has anyone made an at-at out of lego?
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| Hi Luis, Thanks for the ego-boost :) I'm glad you like the AT-ST ... to answer your other questions: 1) I'm planning on taking some pictures this weekend of the components I'm pleased with so far ... that is, the feet, the legs, the head, the (...) (25 years ago, 8-Jul-99, to lugnet.starwars)
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