I built a 3 wheel arduino based bot: http://www.flickr.com/photos/25755276@N02/3429864416/
The third wheel and frame were made from lego.
Any ideas for cheap, non-lego alternatives?
Old toys, look in second hand stores for old used toys(toy cars and trucks). Many of them have wheels, shafts, gears, transmissions, motors, etc.
Hardware stores have all kinds of do-widgets that will fire up the imagination. Electrical switches, wiring, small mechanical parts.
Surplus stores__(Mac's)__ have a lot things that hardware stores have, plus a whole lotta other mechanical and electrical stuff, such as small motors for a buck or so, some of them are the stepping type.
Pretty cool.
I would suggest cheap RC toys - they are much cheaper than anything assembled from individual components (much less durable as well, I guess, but that may not be a problem).
Just one example: you can pick up a radio controlled car from Target for $14 that you can raid for a chassis and drivetrain.
Yeah, toys are a good source but don't overlook free stuff like discarded VCRs, printers, etc. Whatever contains a motor usually contains potential wheels. VCR capstan roller with its existing mount for your front wheel?
Andy,
Is this built from only one lego kit, or you just used parts you had around? Did you use some inspiration or is it totally original?
I find the lego solution one of the coolest: parts are ubiquitous and cheap, they stack up and can be easily assembled amongst them, no screws to play with, no need for tools, only advantages. And it looks good as well.
The wheel and frame are from a $250 Lego Mindstorm NXT. I wanted to give away a few as kits, so I didn't want to break up my NXT and I wanted it to be cheap.
The design is completely original but the inspiration is completely derivative. It is similar to many first bot projects.
Parts from old VCR or K7 recorders
For frames, you can use extruded aluminum, found in many hardware stores. For a small bot like that, it may be a little pricey, but for bigger stuff it seems pretty cheap. It's easy to cut and assemble. Any sheet metal taken from the case of a dead appliance or equipment can be cut into shape. I've even had to pound out bends and folds from the original metal work to get a flat sheet the size I want. Same for plastic chassis parts.
If you can't find salvaged/scavenged wheels, hardware stores sell replacement caster wheels and such that can be used. I've seen them under the two-dollar range. But old broken toy cars ad RC cars are the best source. Many can be found at yard sales and the flea market.