This picture shows my first metal arm (three years old?, center left), two of my wood robot arms (from a year ago), and the prototype UBC student engineers just delivered. It runs a beaglebone black and has two identical sections. The idea is that three sections put together would make a 6DOF arm.

The bad

The third section would have required very expensive Dynamixel motors that were out of budget for this prototype.

The servos are normally 270 degrees, then geared down for power, leaving a range on each joint round about 30 degrees. Not enough to satisfy!

If I were to mass produce this 3D printing would be a total no-no. Cable routing is a mess.

The good

I really like the modular design because I'm always thinking about how to make 1000s more. The math says this arm would be long enough and lift enough weight for my specs. It is surprisingly stiff! I wouldn't have expected the 3D printing to take those kinds of forces. Speaking of which, the 3D printing is gorgeous at 60% infill.

Next

I've been working in parallel on a plan B, so we'll see how that goes and compare the two on the far side.

Also posted on http://www.reddit.com/r/robotics/comments/325bsh/i_asked_ubc_students_to_build_a_robot_arm_for_me/