http://instagram.com/p/o6fQlBofL3/

Just in time for the Vancouver Mini Maker Faire I've assembled all the linkages between the base and the wrist. Everything moves smoothly and the three motors on the top should be able to drive the wrist and elbow. I have the electronics already to drive the rest. I don't have time before the show to add the motors and gearing to make it all go.

I've only had to change the forearm once, to add mounts for the limit switches at the wrist. They serve double duty - making sure the wrist can't turn to far in either direction AND making sure the wrist doesn't hit the shoulder. It's a little hard to see the switch on the back of the shoulder in this photo. when the arm is powered off it rests on the ribs across the shoulder and the elbow motor touches the switch.

Waving this thing around I can see already that the bicep is going to need some ribs to reduce torsion. Also the whole thing is very top heavy. The base will be ~20cm tall. Inside I'll hide the electronics and the power supply, so you'll only have to plug in and go.

I'd love to see someone design an automatic tool changer. Right now my only option is to bolt a tool onto the four screws at the wrist.

A rough measurement says base center to wrist face at full extension is ~53cm. might even go as far as 55. Getting enough power at the shoulder to lift the arm - let alone the 1kg target mass - is going to require some serious gearing. I feel confident that I've got bearing prototypes down now, so that shoulder bearing into a gearbox with something like 200:1 reduction is called for. Hypocycloids, to the rescue! If I can build it parametrically I might use them in the shoulder and base, too.

In the coming weeks I have a bunch of new products to list on my online robot store and manufacturing is taking up a lot of my time. Whenever I get a break I like to relax by playing my game. Maybe you've heard of it? It's called "robot arm". I like a game that doesn't have cheat codes or walkthroughs.

If you're enjoying this project, please pimp it to your friends. Let's see if we can get this thing featured, OK?