Printing for the 8\" telescope has begun
I’m not the first person to build a Hadley 3D printed telescope and then want something bigger. There are two 3D printed 8" telescope designs: the “Bradley” is only available by DMing someone on a discord server, and it’s designed for a printer big enough to fit an 8" circle. I don’t have a printer that big! Thankfully, there’s also the “Leavitt”, a design which splits 8" circles into three pieces so they can fit on a normal Ender-sized printer.
I’ve begun printing all the pieces! It’s a lot of printing; at least 100 print hours. I bought one roll of blue and one roll of black filament. In a telescope, you want to make inside surfaces black so they don’t reflect stray light and brighten the view. The tube parts are so tall and thick, and there’s so many near the path of light, that I used up all my black filament halfway through all the tube sections. I’ll need to print the rest in blue but spray paint them black.
Interestingly, there’s also a remix called the Leavitt Lite which edits the Leavitt to use metric screws/bolts and makes many parts thinner and lighter. One interesting change the Lite made is using a bigger secondary mirror than the original for better illumination; I’ve downloaded the file from the Leavitt Lite and edited it to use #10 nuts so I can use that change too. Now I need to find or buy a 62.5mm secondary mirror.
One other thing to think about: metal rods. I have three 36in thin-walled rods in my wobbly first mount. I could reuse those for my Leavitt for free. My donated mirror’s focal length is 43in right now, meaning I’d need to place the eyepiece 43in away from the mirror, and that won’t fit on those 36in rods.
One option is I could grind the mirror and reduce the focal length to 36in, giving me an 8" f/4.5 mirror, and then use my existing rods. Same focal length means same magnification… but I like the idea of having a longer focal length and therefore more magnification than my previous telescope. Another option: I could either leave the focal length alone (or increase it), but then I’d need to buy 3 new longer 1/2" tubes for an extra $40 or so.
Paint, rods, and secondary mirrors. Many things to think about.