Lower Optical Assembly

Initial prototype

I made the first version of the Lower Optical Assembly while doing the Fab Academy 2018. I was more concentrated on the base and Rocker Box but made a first design of it to get a good idea of how the base will look like.

Initial desing of the Lower Base Assembly
Figure 1: Initial design of the Lower Base Assembly

As we can see, the bearings are defined but there's no pocket holes and the mirror box is only a box with the sides overlapping one over another.

I will start the lower optical assembly by designing the bearing, then a rough design of the mirror box. Next, I will design the globoid gear for the azimuth system attached to the bearing guide located between the bearing and the mirror box. I will finish by doing minor corrections to the mirror box.

The challenge will be the design of the gear. In the first design, I designed the guides with a ¼" plywood. This is problably too thin and will have to increase the thickness to ½" and correct the box dimensions accordingly. The gear system, because of it's dimensions, will have to be printed in sections and I don't know how this will come out and if it will affect the whole system. I will take it as an experiment and will definitively need highly precise printouts.

The bearing systems

I went back to my initial sketch. I tried the slot option to create the pocket but realized that this option was not the way to go. I had to manually put the pocket holes manually for a more pleasing appearance.

The altitude bearings and guide with pocket holes.
Figure 2: The altitude bearings and guide with pocket holes.

I've designed those pockets around the locating bolt holes with a 4° fore and aft of those hole. I used ⅜" radius for the inside of the pocket holes. To my eyes, I got a pleasing result and think that those bearings will be rock solid and light.