Next came laying out the Cherry spoke pattern.... I, to this day 15+ years later, still love the look of the 20" scope, so similar to it, I created massive bearings to scale....
I needed to let things cure so that when the bearing was split into two pieces both would be identical tip to tip. In use the bearings have more spokes towards the end that would not have the box to bolt it to, and therefore would assist in compression when the scope is horizontal (form follows function).... Again calculations show this will not flex of the unsupported section more than 0.0002" in compression. So now it was time to split the bearing ring....
I prefer the FRP (Fiberglass Reinforced Plastic玻璃纤维增强塑料) and Teflon聚四氟乙烯 combination. I've used other scopes with different materials but I think this configuration is better. And folks that have used my scopes agree, it's like butter; no sticking....
I actually was quite pleased with how the bearings turned out.. There are a couple of marks and a little blood on them, but I think they are quite beautiful....
Here is a closeup of the lift bearings. Two 2.375 bearings are side by side on a steel shaft with an off-centered hole through the cylinder. With a slight twist the bearings will rise and make contact, lifting the Alt Bearing a small amount and relieving some pressure off of the Teflon and a jam nut to hold it there....
Three bolts which surround the center pin on which the scope pivots, will press their Teflon pads against an FRP plate on the Ground Board. This removes pressure off of the three 6" diameter Teflon pads to make the scope turn more freely in azimuth. The brass spring-loaded electrical connectors will ride on siver-greased copper rings as the scope turns thereby eliminating any cords. In the Observatory, underground power comes up underneath the scope....
Once the FRP was laminated onto the bottom of the Rocker Box I used whatever I had to press and make good contact. Once again you can see joints are stained. Everything was glued and screwed with excess glue wiped off using a dampened cloth. Stain was applied while the glue was wet since it will permeate the joint when wet but if allowed to dry the glue will seal the wood and no stain will penetrate...
Here the Rocker Box is stained. Only needs Urethaning and parts....
Closeup of the bearing lift system. Also, the two spring loaded pins that ride on the rings are seen in the electrical box and feed three lighter outlets each with a 20A breaker....
On the inside edge of each wall is a Teflon arc which has a recessed spring to keep the Mirror Box centered within the Rocker Box, so the two don't slide perpendicular to the altitude motion....
The Ground Board has the two silver-greased rings and within that is the FRP pad for the three pin-lift bolt/Teflon pads, as well as, the 6" diameter Teflon main pads and a foam capped with Teflon tape dust seal....
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