Grinding is wrapping up for my telescope mirror project. I only have 3 more abrasives left to grind through, and the on to polishing. The project is going very well, and the abrasive is like a powder. It has been rainy the past few days, so that ruled out most of the observing, but before I get into the project, I had a spectacular night with binoculars.
I have a decent pair of Barska 10×50 binoculars, and there were clearings from the clouds and the rain late at night. Cassiopeia is getting pretty high up in the sky now, so that means prime observing time for the Double Cluster, NGC 869. Through the binos, it is large, bright, and resolves approximately 40 stars with an unresolved background of stars. This large bright grouping could even be sen with my unaided eye, as 2 faint small patches of light.
My next target was another Cassiopeia cluster- NGC 7789. It was faint, but there as an irregular glow of unresolved stars. It was nice to see a non-Messier object with binoculars.
Next was M31, Andromeda galaxy. It is easily seen in the binoculars, but not naked eye. The core was bright and obvious and was very large. I could not detect M32 nor M110.
My last target was M33, Triangulum. If you observe in skies similar to mine, you know how difficult of an object this is. I started scanning the area several times, and I detected a faint oval patch of light. I had finally found M33! It was not an impressive view, but It was certainly visible.
It turned out to be a great night, and was good enough for me. Sometimes, small optical devices are all you need to enjoy the night sky. The clouds came and went as the night wore on, but I was satisfied to have my look at the heavens.
In the last post I set up a grinding schedule to accomplish one grade of abrasive every week. It looks like that plan is going to work. I set up my equipment and got to work. I always find it interesting to feel and study the surface of the glass closely and then grind the next finer abrasive for 30 minutes or so and then look and feel the difference. This was apparent after transitioning from Silicon Carbide #80 to #120. These are very coarse grains, but there is a big difference.
It seems impossible that there are still 3 more grades left, because the surface is so smooth to the touch. I opened up the 5 micron container and sampled its size. I detected no difference in texture from the 5 micron to the 15 micron. As I was cleaning up shop for the day, I thought about just putting a layer of plastic wrap over the top of the workstand, then removing it when it is time to change abrasive sizes. That way, I don’t have to clean it outside and re-level the stand each time which would save a huge amount of time.