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David,

Kudos for you doing this engineering experiment.

A friend is bringing over his Celestron AVX next week because it became unmovable in our last cold spell here in Northern Illinois.

I'm expecting to find frozen grease along with overtightened bearings and gears - he bought it used and I'm betting the prior owner overdid the backlash adjustment. That or the factory did in response to persistent complaints about backlash by customers who don't know how to work with less than perfect stuff. I've seen multiple mounts which had the RA and DEC bearing thrust pre-load nuts way too tight. I suspect the assemblers read the automotive spec for the bearings and used that pre-load.

The problem is rampant: Unsuitable grease installed by Sun Bathers in America and China. Same mentality that puts electronic parts only spec'ed to 0 deg C in telescope mounts, as Meade has done in the past.

A decade or so ago a friend of mine had to install heaters on the bearing housings of an early production Paramount because of grease and bearings seizing in the cold. It was installed (as it should be) in an unheated dome in western Michigan. I once installed a small 12V heater pad on a 120V synchronous motor such as we used in the old days pre-servo and stepper.

Things like this bring to mind the Eastern Front in the winter of 1941. Maybe the companies should hire a few engineers from Novosibirsk?

To me I'd worry about excessive wear on the first few gears, even if the mount functions as others have said.

But perhaps there is nothing to be done about it aside from keeping an eye on it.

Again, Kudos.

Mark Christensen