|ABBEY ROAD OBSERVATORY
Telescope Pier Installation Blog
I purchased my Orion Atlas mount used, and I have no idea how many miles were put on it before I got it. The mount was apparently recently hyper-tuned, and for the most part it has been very reliable. I do treat the mount pretty rough; leaving it outside all year, transporting it to the cottage or other observation sites without a case, etc. It was not really until I put my 40lb 10" VRC scope on the mount that I started to see issues with its performance. A number of areas in the mount showed a lot of slop that affects my tracking. Clearly it is due for a major servicing.
With my pier pretty much ready to go (and the weather being terrible), I figured it was a good opportunity to overhaul my mount before installing it in its permanent new home. In the spring I purchased a belt drive conversion kit from TPI Astro when I was at AstroCATS. My plan is to give the mount a general servicing while I install the conversion. The first step was accomplished on Sunday in about 1.5 hrs: disassemble the mount.
One area that I found curiously sloppy is the joint between the mount base and the RA housing. The previous owner, when they had the mount hyper tuned, had three tensioning hand nuts installed through the plastic "Atlas" cap. These three nuts are supposedly for pushing on a steel washing that is on the RA housing and lock it in place. Well, it doesn't work very well. Over time my mount's latitude setting droops under the weight of the mount and scope. Not only that, there is about 0.5 to 1mm of play in the joint side-to-side that allows the whole thing to rock. I pulled it all apart to look at what could be done to lock this joint better once the latitude adjustment is set. Low and behold there is a bolt hiding under the plastic caps that already passes through the joint with a thread on one side of the mount base. I simply added a shim to take up the 0.5mm slop (there was one shim already on one side, I added another), then tightened this existing bolt. With very little torque on the bolt the joint locks up solid...awesome! My plan is to drill a hole in the plastic cap so this bolt is accessible all the time. Why it isn't already readily accessible is beyond me!