Grinding At 12 Micron, Again
Mirror grinding with the newly refurbished tool is going extremely well! After two hours I ran out of 30 micron aluminum oxide grit and moved on to 12 micron. (You can move on when you’ve eliminated pits from the previous bigger grit size, but since previously I was at 5 micron, I didn’t have any pits and could move on whenever I wanted, but I also wanted to grind the tool as smooth as possible).
It took only an hour and a half for the 12 micron grit to eliminate all the pits from 30 micron. Last time it took over 3 hours! Wow.
Now I’m back to 5 micron, the last grit size of fine grinding. Last time I was here, I got scratches. Here’s hoping a few more hours of work with my refurbished tool will let me finally finish fine grinding. The picture shows how much of the tool is texture-free now and making good contact.
Oh and all these hours of grinding have moved my focal length from 37 inches to 39.5 inches, making this mirror a 12" f/3.3. Anything below f/3 is incredibly hard to parabolize, so this will make it easier for myself. This telescope is going to have such bright views.