Making a 27 inch Cassegrain telescope mirror. In this video, I am rough grinding a twenty-seven inch Cassegrain telescope mirror. I discuss several issues relating to the project as I begin what will ultimately be a very long project.
The mirror was ground to a very fast f/3.5. I am bringing the curve back to an f/4. I anticipate that this will take between twenty and fifty hours of work before fine grinding can begin. Fine grinding should go relatively quickly, about twenty hours. Polishing will take around fifty hours and figuring should take between one hundred fifty and two hundred hours, depending on problems that might arise.
As the blank is very heavy, the project cannot be transported. It is in the Flander's Pavilion at Stellafane. It is inaccessible in the winter so this will be a three season project. I work during the week, so I can only work this on Saturdays.
Over the winter, I will concentrate my energy in making the Cassegrain secondary mirror for this telescope. It is a convex hyperboloid with a conic constant of -2.25. A real challenge!
This is sure to be a fascinating project. Please check back for periodic updates.
Tags: Making a 27 inch Cassegrain telescope mirror, amateur telescope making, telescope, cassegrain, Francis J. O'Reilly, Francis O'Reilly, science, astronomy, hobby, Stellafane, Cassegrain Reflector, Making, Space, Mirror (Product Category), Springfield, Vermont, Moon, optics, do it yourself, observatory, optical fabrication, Flanders Pavilion, Russel Porter, David Tabor, Jack Von Hind Lick, Beagle