Lucas Sifoni

A lightweight and easy to build 1.25" crayford focuser


Taking inspiration from how the 2” focuser built for K2 (see : Heavy modifications to the 200mm f/3.52 dob’s upper cage. ), I have drawn a 1.25” crayford focuser for an upcoming ultralight dob build.

It is very simple in terms of BOM and assembly. Three parts need to be printed :

The needed vitamins / hardware are :

M3 screw Length 20mm 4
623zz bearing4
Knitting needle dia 3.5mm, smooth 1
M4 screw length > 20mm 1
Copper strip used for eyepiece compression 1
M5 screw nylon tipped, knobbed 1
Aluminum strip 58x10x2mm 3

The files are downloadable here :

It handled precisely moving my Hyperion zoom eyepiece (300g), even upside-down (which doesn’t occur in practice), while only weighing 100g with my printer settings (3 perimeters, 0.2mm layer height, 30% gyroid infill).

Here’s a bad picture of the yellow PETG prototype, awaiting to be re-printed and mounted on a scope :

Feel free to reuse the files as I declare them licensed under CC-0. Happy new year.

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