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Subject: 
Re: How much weight can a LEGO chassis carry around?
Newsgroups: 
lugnet.robotics
Date: 
Sun, 11 Dec 2005 08:38:17 GMT
Viewed: 
1660 times
  
In lugnet.robotics, Joe Strout wrote:
   I’ve recently gotten my hands on a Pololu motor controller which I can control from my Macintosh (see my tutorial if
you’re curious). This has me dreaming of mounting my laptop on a mobile
base; with a web cam, speech synthesis, big graphical display, speech
recognition (in quiet environments), etc., I get a lot of robot goodness
• very quickly that way.

So now I’m wondering whether it’d be at all feasible to build the chassis
out of LEGO. The laptop weighs 5 or 6 pounds.
I don’t need it to move around in a particularly speedy manner, but faster
than a turtle would be nice. I can use
multiple motor controllers to drive more than 2 motors on a side, if that
helps.

Does this sound doable, or am I wasting my time? If borderline, do you have
any building tips to make it more likely to work?

Thanks,
– Joe

Hi
I’ve read the other messages in this thread, got ideas, wondered if I should
reply to one of them, then decided to start a new branch instead.
Ok, now some food 4 thought:

(I never tried any of these, they’re the result of some mind-based simulations.)

Idea 1
Build the platform, starting with baseplates,

...with the 8x16 plates centered on the sides of the 16x32 plate, leaving 8x8
spaces for the wheels. A frame can then be built on the baseplates.
The sides of the frame can be built out if the load will be longer/wider then 10”
The motors, tranmission, etc can be laid at this point and tested.
The whole thing can be covered with plates, giving a flat surface to work on
This combination of baseplates, a frame, and plates on top will have a high
strength-to-weight ratio, like a hollow-core door.
Wheels can be attached to Turntables:
http://www.bricklink.com/catalogItemPic.asp?P=2856c01
which would be built into the corners, upside down. The bottom (now the top)
portion of the turtables would be solidly attatched to the platform. The top
portion (now the bottom), which would be free to rotate, would have its
ouside gear teeth geared directly to the steering system. The center is left
open to allow the driveshaft for the wheel to pass thru.
If you could get the turntables to turn in such a way, the whole bot
could turn in place, rotating about its center axis.
One thing I found out about turntables: They’ll start to bind under 8 ounces
of load, and may not move at all under more then 4 pounds. You could put
something (ball bearings?) in between the turntable top and bottom and keep
the 2 about .002” or more apart. Otherwise, as long as you keep its total
weight under 16lbs, it’ll prolly be OK. Just make shure your steering
mechanism has enuff power/strength to turn those turntables.

Idea 2
Same as above, except use a piece of plywood instead of the baseplates, and
cut an 8x8 square hole in each corner. The turntables would be built into
LEGO “boxes” that fit into the holes in the plywood. The boxes would have a
1-stud-wide ledge, having the apearance of an 8x8 box on a 10x10 platform.
These would be inserted thru the plywood from below, allowing the plywood to
rest on the 1-stud-wide ledges.

Play Well

scott “I just gave an idea that goes aroud and comes around” Frischmann



Message has 1 Reply:
  Re: How much weight can a LEGO chassis carry around?
 
The answer to the question "How much weight can a LEGO chassis carry around?" has got to be "Infinite" (assuming that you have infinite amounts of Lego as some people here appear to have!). How's this for a thought experiment: Build a perfectly (...) (19 years ago, 11-Dec-05, to lugnet.robotics)

Message is in Reply To:
  How much weight can a LEGO chassis carry around?
 
I've recently gotten my hands on a Pololu motor controller which I can control from my Macintosh (see my (URL) tutorial> if you're curious). This has me dreaming of mounting my laptop on a mobile base; with a web cam, speech synthesis, big graphical (...) (19 years ago, 8-Dec-05, to lugnet.robotics, FTX)

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