Consider using square 1"x1" aluminum profiles with a thickness of 1/16" inch for robot parts as they provide more strength and stiffness than thinner angle profiles while having the same weight. Welds on thin materials are easy to break under force so reinforce welds and use areas with concentrated forces. Rotational joints are easier to design than sliding joints which require a width to length ratio of 2 or more for stability. Follow guidelines for arms by making them slow moving, rigid, and lighter at points farther from the pivot. Use electric motors if precise stopping is needed or pneumatics for extreme positions only. Add potentiometers to all pivots for remote adjustment and full range of motion feedback.

1. Robot Building Best Practices FIRST Kickoff Novi, MI 5 January, 2002

2. Consider alternate aluminum profiles Angle: 1”x1” 1/8” thick Square: 1”x1” 1/16” thick Same weight, much more strength and stiffness The possibilities are limitless:

3. Weld easy to break (force causes tension) Stronger weld (force causes shearing) Be careful with welds Reinforcement

4. Be careful with concentrated forces A thin wall is easy to tear. Reinforcement makes the wall harder to tear.

5. It is easier to make a good rotational joint than a sliding joint

6. Sliding joint ratio WIDTH LENGTH LENGTH WIDTH 2