The focuser on my homemade scope was attached with screws at a 30 deg. angle from the optical axis, which means they're not perpendicular to the surface of the tube. The hole in the tube was ragged, the screws were holding on by a shred, and the focuser was a little wobbly.

This backer and filler provide a large surface area that conforms to the tube and a flat surface for the nuts. The focuser is solid now.

Dimensions:

Tube outside radius: 104.4mm

Tube inside radius: 100.6mm

Radial separation of screws on the surface of the tube: 45mm

Axial separation of the screws: 31mm

Focuser tube OD: 42mm

Since it's unlikely that your scope tube and focuser will exactly match mine, this is more for inspiration than for practical use.

As a bonus, I've included a file for the rim I printed for the edges of the tube. Print 4X for front and back.

UPDATE 07/10/2018:

Added parts for a Meade 8" reflector. Dimensions:

Tube outside radius: 121.44 mm

Tube inside radius: 114.84 mm

Radial separation of screws on the surface of the tube: 69 mm

Axial separation of the screws: 40 mm

Focuser tube OD: 42mm

Print Settings

Printer Brand:

Anet

Printer: 

A8

Rafts:

No

Supports: 

No

Resolution:

0.1 or 0.2 mm

Infill: 

100%

Notes:

I printed the backer without supports and the recesses came out nicely. Print temp for PLA was 205C and print speed was 50 mm/S.

Category: Physics & Astronomy