Skywatcher 250P Tri Bahtinov Mask

thingiverse

This is a tri-bahtinov mask for the Skywatcher 250p. The tri-bahtinov is similar to a traditional bahtinov mask, but it gives you an indication of your collimation at the same time as focus. I generated a 2d SVG from this page: https://satakagi.github.io/tribahtinovWebApps/Tri-Bahtinov_symmetric.html From the SVG, I extruded and worked on it a bit in Blender. The parameters I chose for the generator were specific to my scope, resulting in an aperture of 254mm, focal length 1200mm, and central obstruction 50mm. The STL provided is basically the thinnest you can get away with, but if you want it to be more sturdy, just scale the whole thing in the z-axis. I scaled it so that the main plate was 6mm thick, and the lip around 10mm. Completely over the top, but I like it! The wafer thin version works just fine, but could be a little fragile. The outer diameter is 285mm, which is too large for many printers. I printed it on my Ender 3 Max. It works like an absolute dream, and it's quite beautiful when focusing in on a bright star. More information available here: https://satakagi.github.io/tribahtinovWebApps/Tri-Bahtinov_symmetric.html