Lidar - full redesign

After the first prototype print, I found several mechanical issues which could have been avoided had I taken the time to rethink the placement solution. I redesigned the quadrature encoder wheel to be something closer to what a shaft encoder (in principle) would do. 

I have also considered using an absolute encoder and gear ratios. I know that I have less to worry about in regards to 'belt slip' with the use of a timing pulley. However, I am always concerned about the wear and tear causing slip than anything else. The most common mistake when building a timing pulley system is tightening the belt too tight. This will eventually deteriorate the belt and slip will be introduced before belt breakage occurs.

Obviously the best redesign of the entire solution (if I were not already committed to using off-the-shelf components) would be to redesign the slip-ring itself... I have considered this task, several times already. 

The main issue I have against redesigning the slip-ring is that: 

1. I would not be using off-the-shelf components which would be easily source-able for anyone else to build one of these. And... 
2. I have been down this road before on another robot. Designing a slip-ring can become hard to manufacture... but I might take another stab at it eventually (with all my lessons learned up front).

I oriented the optical interrupters to be above each other. Overall I think the height increased by 5mm or so in Z... it's not a bad trade off since the horizontal is about 9mm shorter in X now. I also drastically increased the wire feed hole through the lidar case mount - through the top). Unfortunately it is not visible from the above view.

I also added zero-ing text so it is easier to explain the quadrature encoding to others. I had so many people ask me where zero was, I decided to just make it visible for all to see, rather than searching the entire part for the misaligned holes.

So, now I feel the quadrature encoding is much more clear for others from the above picture.