PopeScope Gets Buck's Gears Upgrade

 
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It began with an aborted second attempt at a photographic Messier Marathon. Loaded with a 90mm StellarVue triplet, two cameras and extra balance weights, the PopeScope began tracking very badly in exposures of more than 45 seconds. Four out of five images were either exotically trailed or contained "double stars" - the result of the scope sticking, then releasing during tracking. As it turns out, a layer of clouds that rolled in around 2 AM would have brought the effort to a stop, anyway.

The next morning, with some help from friends, the PopeScope was taken down off of its AstroPier and stretched out on a temporary workbench inside the observatory. Disassembly of the mount base revealed a fair amount of contamination (a strange, plastic "sawdust"), exhausted grease, a scraping battery cover and nylon gearing. Although it was hard to directly blame any one of these conditions for the previous night's problems, they certainly weren't helping.











I immediately ordered a "Buck's Gears" kit from Peterson Engineering and it arrived just a couple days later. This was the second Peterson upgrade purchased for the PopeScope; I had previously installed the clutch kit. I have nothing but positive things to say about the Peterson kits - they are exceptionally well documented and if you have a question, Pete himself often answers his email within a few hours, even on weekends.

It should be noted that the Buck's Gears kit is not for the faint of heart.  It requires an extensive disassembly of the drive system and the LX200 mount base doesn't have a lot of working space. That said, the instructions are excellent and easy to follow.

It took a several hours to disassemble the drive, replace the gears, make the adjustments and get everything back together.  In my case, I discovered that I needed to remove some metal on the face of drive motor block to improve the gear mesh; that took extra time. When I finished the RA, I decided to short-cut the Dec work and I just installed the improved spring and stand-off pin. Since the Dec drive can be worked on while the scope is on the pier, I will come back and do that one later.

PopeScope on the workbench in observatory; one observer noted that it looked like a "beached whale"

The inside of the LX200R's mount base when disassembled

Close-up of nylon motor and worm gears, as well as crud on worm and other drive parts

Outcome?  Well, the scope sounds different - markedly less of the coffee grinder noise that is common with LX200s. Slews appear to be more accurate and native PE before correction is smaller - now about 15" peak to peak. I still have more backlash in Dec than I like, but I hope to reduce it when I upgrade that drive in a few weeks. Overall, I think the Peterson Buck's Gears kit was a good investment in time and money.

Dr. Megna performs surgery on the PopeScope