Iterative improvement

A person who sees something in their mind that isn’t real and believes it actually exists is generally regarded as insane. A person who sees something in their mind that isn’t real and makes it actually exist is regarded as a visionary. Not claiming to be either of those. But I do on occasion see things I know could be made better, and make that improvement real. Which makes me an ORSA.

A number of years back I managed to snag a motorized focuser for the NexStar. The tiny fine-focus shaft on the Feathertouch already installed was about a half millimeter smaller in diameter than the Feathertouch on the CPC11 I sourced the focuser from. So being the resourceful individual I am, I made the smaller shaft larger via use of a bit of heat-shrink tubing. Which works great for stars, since fine focus is less critical than for planetary work.

Fast forward to yesterday, and the little bit of slop in the focus shaft (due to the filler being old, and rubber) made fine focus for getting surface detail nearly impossible. The rubber ‘bushing’ was allowing slippage, and when I tightened the set screw to get better purchase, it compressed the bushing opposite the screw, and caused the gear to now be non-concentric. No bueno. Enter the tin snips and an empty coke can…

Shim bushing raw material

Here you can see the original bushing: old, compressed, and looking a bit the worse for wear –

Ancient bushing, no longer cutting the mustard.

And the new one installed –

Size reference: Hex key for the set screw? 0.050”

Aftermath –

Managed to cut open a Coke can and make a bushing, and all I got for my trouble were these two cuts…

Gear now spins concentric on shaft, with zero slop. Also, the person who specified a 7/64” hex key for the focus motor collar screw is an evil bastard. Hopefully this sorts the focused out so I can screw up Monday’s Saturn / Jupiter conjunction some other way…

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