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Subject: 
Re: How much weight can a LEGO chassis carry around?
Newsgroups: 
lugnet.robotics
Date: 
Fri, 9 Dec 2005 05:03:48 GMT
Original-From: 
steve <sjbaker1@airmail.netSPAMLESS>
Viewed: 
1537 times
  
John Barnes wrote:

The Achilles heal is the bearing ability of a cross axle in a hole. Above a
certain load, you will make a constant supply of ABS dust, which means you will
have to replace a few key pieces from time to time.

Yeah - but you can add more axles and more wheels so that the load is
shared across more axles.  That keeps the distance between the
axles small which helps out with chassis stiffness issues too - and
since you'll probably want more than two motors to drive the behemoth,
it won't hurt to have more driven wheels either.

If you think of just a bunch of wheels in a long line though, you'll
find that steering gets a bit problematic because with that many wheels,
you are more or less forced into skid-steering - which gets
progressively harder the more wheels you have.  Also, you can't easily
widen the platform without it starting to sag in the middle - you could
add a center row of wheels - but that would just make skid-steering
even harder.

The answer would be to build a Synchro platform.  You can just keep
bolting on more wheel modules and more motors to make something as
big as you like - if you double the number of wheels, motors, and
axles, you double the carrying capacity.  I don't see any particular
limit to the size you could make that.

Imagine taking (say) four of these (16 wheel units!) and bolting
them together:

      http://www.visi.com/~dc/synchro/index.htm

So - who's up for building the first ever human-rideable Lego robot?

That would be *so* cool!



Message has 1 Reply:
  Re: How much weight can a LEGO chassis carry around?
 
(...) Right, at least with differential steering. I've been thinking that perhaps I would be better off with Ackerman steering (like a car). And while I'm at it, I wonder whether I might have the back wheels turn as well as the front wheels -- (...) (19 years ago, 9-Dec-05, to lugnet.robotics, FTX)

Message is in Reply To:
  Re: How much weight can a LEGO chassis carry around?
 
(...) The Achilles heal is the bearing ability of a cross axle in a hole. Above a certain load, you will make a constant supply of ABS dust, which means you will have to replace a few key pieces from time to time. Beyond the actual bearing surface (...) (19 years ago, 9-Dec-05, to lugnet.robotics)

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