[R1ffSurf3r]

I'm on sketchy Internet in Germany right now so I can't post any pics, but the arm is relatively simple. Our best example would definitely be 2011, which in my opinion is the best robot 233 has ever produced.

We use three different sizes of box tube, with fancy bearing blocks holding it all together. The telescoping action is powered by a motor at the bottom and chain.

The most complicated pieces are probably the bearing blocks. I believe they are cut with a wire edm and milled, and everything moves smoothly with rollers. Its hard to explain without pics, but there are blocks on the inside of the tops of the tubes, and the outsides of the bottom of the tubes. If you find a good pic this will make a lot more sense. We keep about 6 inches of overlap when fully extended. In 2010 we tried out using waterjetted delrin in place of these rollers and blocks, and honestly it just sucked so don't bother.

Some other cool features of the arm include dual constant force springs that entirely counterbalance the telescoping portion, and a less slick system of surgical tube to balance the rotation. There are also delrin springs that act as shock absorbers when the arm retracts and slams closed. For rotation the whole arm sits in split bearings. But honestly the coolest addition to the 2011 iteration is how the rotation was powered. Instead of using chain like usual, there was one giant wire edm cut gear that fit directly to the arm.

Now all of these features aren't entirely necessary for an effective arm, but are the result of continuous improvement over the years. Effective programming and intuitive driver control should be considered the highest priorities in my opinion.