Aperture Mask / Primary Mirror Mask for Newton Skywatcher 200mm (8"), d=196 mm

It is recommended to add an aperture mask to cover the rubber holders. These protrude into the mirror surface area what you can see in the diffraction spikes on bright stars.

Printing:

~ 25 grams, Nozzle 0.4 mm or 0.6 mm (usually faster), material doesn't really matter, PLA or PETG, layer height 0.2 mm or 0.3 mm, 2 wall loops, 3 bottom layers, 4 top layers, infill 10%, no brim.

Painting

It is recommended to paint the mirror mask with black anti-reflective paint or to cover the top and bottom with an adhesive foil made of black velour velvet fabric.
I covered one side with foil and one side with paint. Painting the inside diameter is important!

Assembly

Gently tight the mirror holders. Do not tight too much, this induces stress on the mirror and can lead to visual impairments.

Some people recommend taking a sheet of paper, placing it between the mirror and the rubber buffer and pulling it tight until the paper is a little harder to pull out.

Sizes

Customize the FreeCAD model to your needs.
You can find a mirror mask for Skywatcher Newton 150 mm here.

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