StubScope - 70mm Telescope with 2" Crayford Focuser

This is a complete set of prints for a 70mm aperture wide-field astronomical telescope.

It is an advanced build as you will need to do some basic engineering - notably tapping!

You will need to add some additional parts.

A 70mm (nominal) diameter lens. The 'high quality achromatic doublet' one from Astro Media is ideal http://www.astromediashop.co.uk/Components.html

This has a focal length of 280.1mm but you can use any ~72mm diameter lens and adapt the tube length to suit.

A length of 76mm o/d by 3mm wall thickness aluminium tube, about 100 mm shorter than the focal length of your lens. Expect to experiment to find the ideal length for your lens. (I have edited this to recommend a shorter tube in case you want to use thw scope with a star diagonal - I recommend starting with an over-length tube and shortening it until you get the focuser range you need.).

Four 3mm bore by 8mm diameter ball races https://www.arceurotrade.co.uk/Catalogue/Bearings/Ball-Bearings-Metric/3mm-Bore

Two 4mm by 8mm diameter ball races

Lengths of 10 x 2mm and 15 x 2mm aluminium extrusion (try B&Q).

A length of 4mm stainless steel rod.

Matt black stove paint.

Adhesion primer and suitable paint to finish the tube.

M3 screws in various lengths (5mm countersunk, 10mm cap head, 25mm cap head).

M6 x 25mm nylon screw.

Two M4 x 15mm nylon screws of knurled thumbscrews.

An 18mm square of teflon or similar slippy plastic.

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