Mobile Robot, With Printable Gearbox
by NickAmes, published
This is a small two-wheeled robot designed for pattywac's bearing contest. It is similar to other robots available on thingiverse, but it is unique in that it does not use gearmotors or continuous rotation servos, but plain dc motors and a makerbot-printed geartrain.
Although the printed geartrain is incredibly noisy and not terribly efficient, it is much cheaper than any gearbox that one could buy. Also, it's printed on the makerbot, which is pretty neat.
-Makerbot Printable Geartrain (8:1 reduction)
-Printable without heated build platform
-3mm holes in chassis and cover for easy modification/expansion
-Can accommodate motors up to 25mm in diameter (comes set for 22mm in diameter) and up to 30mm long.
This is the abbreviated version; see the README file for more detailed instructions.
The robot is made of two identical halves, that each contain a wheel and the geartrain for that wheel. The wheel is clamped on the bearing with a M3 bolt that goes through the wheel and the output gear; the wheel and output gear shafts mesh inside the bearing bore to transmit torque. There are two middle gears between the output gear and the motor pinion.
After the chassis has been assembled, a cover is attached. There are several options available. Cover_Grid.stl is a cover with 1cm spaced 3mm holes. The two arduino covers allow an arduino to be mounted on the top of the robot. Cover_Solid.stl is a cover with just screw holes and a hole for the motor wires. Cover_Blank.stl is a cover without the top and bottom faces filled in, to make making your own covers easier.
The assembly instructions can be found at: http://www.flickr.com/photos/nickames/sets/72157624952160443/