Marginally Clever commissioned a robot arm prototype from UBC mechanical engineering students Liam Hodgson, Lucas Porto, and Oliver Wolfond for ENPH 459 in the winter of 2014/2015. Their design is modular - three repeating sections that can be put together to make a 6DOF arm with 50cm reach, 1kg mass at the wrist, and 1mm repeatability. This design meets all those requirements.
In total this project cost a little over $500 CAD and the final complete arm would have been somewhere around $1000. The custom parts are 3D printable, the rest is available for purchase from sources like McMaster-Carr.
The controller is a BeagleBone Black with sparkfun level converters. All three stages are identical. The picture shows the wrist and elbow stage. The shoulder stage would need Dynamixel servos of the same size that are three times the price. get the BBB source code
Due to the limitations of the servos, the range of motion in each joint is approximately 30 degrees. Marginally Clever feels this is not usable for practical applications as is. Rather than let it go to waste, Marginally Clever is releasing the plans on the internet for anyone to remix. Perhaps you can learn something from our prototype. Maybe you can improve on the Solidworks files (zipped) and make a better machine. If you can widen the range of motion while keeping the position feedback AND the price under $1000, call us: We have opportunities waiting for you.
Marginally Clever is committed to building a low cost arm and making it available to everyone. Follow us online, say 'Hi!' at a Maker Faire, and tell your friends. Together we will do amazing things.
Please see UBC-arm-how-to.pdf for all the assembly instructions.