Track doesn't track

Monday, January 17th, 2022

Initial test on last Friday shows that the arm can be raised and lowered, and moved to different positions. However, the performance is not stable due to two reasons:

1. When the outer tube turns to rotate the arm, the pusher & rack in the track actually turns with it. This is likely due to the friction between the pusher and the inner walls of the outer tube.

2. When the outer tube turns, it wobbles too much and makes the holes between the outer tube and the track misaligned.

To address these two issues, the team came up with the following solutions:

1. Add notches at the back of the pusher with corresponding grooves in the track. This assures the pusher is constrained to only move vertically.

2. Add a shoulder at the top of the track to cover a part of the lower end of the outer tube. This further assures that the outer tube is constrained to only rotate.

Moral of the story: always constrain the movement of moving parts!