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Bearing Woes
Hi,
Just a quick hint on getting smoother azimuth motion.
On my 12" Dob ,my centre pin assembly is made out of crappy stainless rolled tube, which isnt even round.
The bolt is also very sloppy and rides on the "thread part".
What I have done is got 1 off Stainless bolt (10mm), with a straight shank of 35mm. I then machined up a brass bush that fits perfectly over the new bolt and sits inside the original hole in the wood. Some good quality grease also in the bush for good measure.
I also machined up a teflon centre bush, exactly 3mm diameter (same height as the outer 3 stock sliders.) And lastly, I made up thicker and wider stainless steel washers to replace the crappy cheap ones on the 2 outer surfaces.
This new bearing assembly worked way better than I expected. My 12" scope can now be pushed around with my pinky finger, even at the zenith. This is not an exaggeration.
On my scope anyway, I am certain that the centre assembly caused the bulk of the "drag" in stock form. Maybe people should also look at this part of the assembly at getting better motion as it is not often discussed here?????
btw, lastly I put car polish on all the sliding surfaces of the dob.
(I will post pics of my modsas soon as I borrow works camera)
Mark
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