This is my first post. I have been a member for a while and I'd thought I'd share a recent project I complete for my NexStar 4SE.
I had been searching for a solution to a common issue on the 4SE related to the scope shaking when attempting to fine focus objects. It could be done but it required a lot a patience and a steady hand. I had attempted several of the suggestions found on the forums but was not happy with the results. So, I decided to try to create a better solution.
What I came up with is a gearbox that can be mounted on the scope the reduces the focus by about 0.17. This allows for very fine focus and as a bonus also reduced the amount of shake in the scope. Keep in mind this was created mostly from spare parts I had sitting on the shelf and 3d printed parts. I will include a complete list below if anyone is interested.
Everything here can be adjusted except the two main shafts and timing gears The GT2 60 Tooth and the GT2 16 Tooth. Changing those will change the required length of the belt (GT2-200). All the rest of the gears can be adjusted to fit your needs.
In the pictures I did not have a spare 5mm collar for the top shaft, so I just used a spare timing gear in its place. Keeps the shaft from sliding out.
Some sanding and fitting may need to be done to the supports to get them to fit snug. The pin bearings are just press fit into the sides of the gearbox. And the shaft lengths could be reduced. 100mm is just what I had. Anything longer than 60mm should work.
A couple of things to note and things I may change if I revise the design. Near Zenith the gearbox will fit the WiFi module if you are using one. All the printer parts were printed with 1mm wall thickness and 50% infill. I wanted to be sure they were stiff enough. Probably overkill.
SLT Files will be in a second post
Parts List (From Amazon)
Hex Socket Head Cap Bolts Screws Nuts - M2x8 (16) / M3x (12) with nut
Hex Bolt Std ¼” x 1 ½” (1) with Butter fly nut. (Home Depot from the loose bolts bins)