StubScope - 70mm Telescope with 2" Crayford Focuser

thingiverse

This is a comprehensive set of prints for a 70mm aperture wide-field astronomical telescope. It's an advanced build, requiring some basic engineering skills - specifically tapping! You'll need to add several extra parts. A 70mm (nominal) diameter lens is necessary. The high-quality achromatic doublet from Astro Media is ideal at http://www.astromediashop.co.uk/Components.html. This lens has a focal length of 280.1mm, but you can use any ~72mm diameter lens and adjust the tube length accordingly. A length of 76mm o/d by 3mm wall thickness aluminum tube, about 100 mm shorter than the focal length of your lens, is required. You'll need to experiment to find the ideal length for your lens. I've edited this to recommend a shorter tube in case you want to use the scope with a star diagonal - start with an over-length tube and shorten it until you get the focuser range you need. Four 3mm bore by 8mm diameter ball races are needed from https://www.arceurotrade.co.uk/Catalogue/Bearings/Ball-Bearings-Metric/3mm-Bore. Two 4mm by 8mm diameter ball races are also necessary. You'll need lengths of 10 x 2mm and 15 x 2mm aluminum extrusion (try B&Q). A length of 4mm stainless steel rod is required. Matt black stove paint, adhesion primer, and suitable paint to finish the tube will be needed. M3 screws in various lengths (5mm countersunk, 10mm cap head, 25mm cap head) are necessary. An M6 x 25mm nylon screw is also required. Two M4 x 15mm nylon screws of knurled thumbscrews are necessary. An 18mm square of teflon or similar slippy plastic is required.