There are a few good ways to get rugged robot bases with minimum
costs. I prefer pre-made equipment you can get cheap.

For 12v motor/gearboxes, check your local auto wrecker for
windscreen wiper motors, these have a very high torque motor and very
rugged worm gearing about 50 to 1. Perfect to just fit a wheel on
the shaft. Ask the wrecker guy which ones he never sells, they
will be cheaper and you know that brand motor are reliable! :o)

For coupling wheels to make "tracks" or differential drive,
buy bicycle chain (and maybe sprockets) from the local pushbike
shop. These are very cheap and very strong. You can cut your
own sprockets from alloy 1/8" plate with a drill and file.
I have made a heap this way.

I would forget the timing belts as they will keep coming off the
runners, its hard to do it the way you are trying. They need the
lumps on the inside to locate them on the runners. When the belt
is inside out as soon as you do a turn on the spot it will rip
itself off the runners. What I would suggest is four wheels,
lawnmower wheels from any hardware store, and driven as two
pairs with bicycle chains. This will give full differential
wheels and is from memory the same system the original radio
controlled K9 was built. That's why K9 has the skirt. :o)

Hope this helps. The widscreen wiper motors will take your arm
off, espcially if you get the series wound (not perm magent)
stator types.
-Roman











Dan Michaels wrote:
>
> Peter Wintulich wrote:
> >Hi,
> >There is a good option for building catipilar track base.
> >Use timing belt inside out so the teeth are the tred. Some belts
> >have a rubber backing that helps with power transfer from the drive.
> >If the environment for the base to run on is clean then the belts could
> >be driven from the touthed side.
> >
> >This is what I am planning for a K9 (DrWho) type robot dog.
> >
>
> Hi Peter,
>
> Why not just put a K9 shell over top of an RC model car | truck
> of some sort? What amazes me, from looking around many robo-sites,
> is everybody has their own expensive platform with wheels. Most
> are very top heavy and shaky, or just little warts with wheels.
> All are incredibly expensive for what you get, and none of them
> looks worth spit for mechanical worthiness.
>
> OTOH, there are dozens of model cars with mobile frames already
> built, and waiting for a good hacker to come along. Seems a good
> choice would be a frame with powerful low-gearing and big wheels.
>
> This one is pretty interesting, but lotsamoola $$$$$$$$:
>
> http://www.irobot.com/ir/index.htm
>
> Also, Robo-Dogs, Robo-Vacs, and Robo-Mowers are hitting the
> markets - got a few links up on these:
>
> http://www.users.uswest.net/~oricom/emerge5.htm
>
> Somebody musta done an R/C-Car-Robo-Hack. Seems so obvious.
>
> - Dan Michaels
> Oricom Technologies
> ===================

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