Telescope Focuser

UPDATE 2/15/2025
• Cleaned up Files and Text
• Added HELICAL-Gears for Smoother turning and less Backlash
• Replaced the CAP with Revised Design (Larger Counter-bore for Nuts/Washer. Can now put Screw in from Top, Washer/Nuts on Bottom.
• Deleted Non-Helical parts/gears
• Added MountingBase to hold Foot more securely
• Added Cover with Hole for Screw (use Screw instead of Dowel-Pin if desired)

Elephant's foot: In most printing's the Bottom layer will be enlarged (called 'Elephant' foot) - that may be a problem, particularly on the Gears.

Some Print Software, such as ORCA, has an Elephant-Foot compensation feature... you decide how to deal with this. The 'goal' is for relatively free-turning Planet-Gear without too much binding or slop.
If it's a minor binding, don't worry about it as it will loosen up with usage.

The Hole (for Dowel Pin's) on Planet-Gears is sized to accommodate some Shrinkage but the Elephant foot may need some attention (with a Jeweler's Round-File or other). To help reduce a 'tight-fit' on the Dowel-Pin, The Planet-Gear's have an enlarged Hole (Planet-Gear3-24, meaning, Hole=3.24mm).

UPDATE 2/7/2025: Added a 2-Stage design/parts.
A 1-Stage is basically as Originally-Posted and I will leave the previously posted Photos. The Gear-Ratio (as seen by the stock Focuser's Knob) is 1:3.7

A 2-Stage adds a Geared-Carrier (having the Sun-Gear on underside to mate with Planet-Gears). The 2-Stage Gear-Ratio is just under 12:1 (as seen by the stock Focuser's Knob).

DO NOT Use Stock Knob for focusing as it presents 1:12 loading on the Gear-Train.

IMPORTANT: Gear-Backlash (Gear-Slop) will happen for basically two reasons:

1. Material Shrinkage
2. I designed the Parts to be somewhat 'Sloppy' to accommodate the variability of User's printers and filament's used without the need for Scaling. Some User's may prefer to minimize Backlash by Scaling Parts.

I recommend printing AS-IS and assessing if Scaling is needed/desired.

Scaling-Example: If wanting to Scale something by 1/2 % (0.5%) you would set the Print-Scale value to 100.50

Both .STL and .STEP files are posted. STEP files are easily tweaked in CAD software and so are the .STL files but, depending on software, User may need to Clone and/or do a BOOLEAN, Fusion, Compounding operation.

NOTE about the Screw & Nuts: To avoid the Nut from Self-Tightening/Loosening, use Nail-Polish, Thread-Locker, Crazy-Glue...etc.
First tighten to appropriate amount then Drop the Glue/Polish onto it.

(Note: Can build a 1-Stage unit with the same parts... Without Planet-Carrier)

The Only items that are specific to the StarBlast are the CAP (the part that gets pressed onto the Scopes Knob) and the RING-Gear's Foot that sits on the Scope's Tube to keep Ring-Gear from rotating.

With user modification's to these two items, it may be adequate for other Telescopes.

The Dowel Pins to use are 3x10mm and can be purchased at Amazon and elsewhere for a few dollars...
The Screw, Nut and Washers are M3 or 4-40. Use some Thread-Locker or Crazy-Glue to keep from un-screwing. The Sun-Gear should spin freely without un-screwing Nut&Screw.

Generally, if you have specific Geometry, I'll make modifications for your Scope. Post your Request.

There are two Knobs to choose from... If desired, there's a Set-Screw hole (you can Self-Tap the thread using a Screw)