From the ATM List:
Ed Witkowski .... subject: ATM Delmarva Mirror madness
This past weekend I attended the Delmarva Stargazers 2nd Annual Mirror Making Seminar or was it "Grinding Mania!!" or should it have been "The Mirror Marathon".
Whichever term applies, it was great. We started on Friday afternoon with a quick introduction followed by the fine grinding of our generated blanks, a 10-inch f6 in my case. The grit sequence was Silicon Carbide, SiC, 220 grit, Aluminum Oxide, AlO, 25, 12, 5 micron and then Cerium Oxide, CeO, polishing agent.
Rough and fine grinding is somewhat "mechanical":
1. Put some grit on the tool and mirror
2. Do the 1/3 center over center "Boogie"; I mean stroke, turning the mirror and "going around the barrel".
3. Go around twice,
4. Dunk mirror and tool, clean off sludge.
5. Do step 1.
6. Do steps 1 through 5, 8 times (this is called a wet), clean your tool and mirror very thoroughly and go on to the next grit.
We did approx 16 wets between the 220 and 25 micron. By the time Friday night rolled around, I had completed the fine grinding and was ready to start polishing in the morning.
"Ah, pitch in the morning, smells like, (sniff, sniff) victory". Pitch, messy stuff, but fun. Was it hard or was it soft? All I know is it worked.
The Cerium Oxide was polishing the glass well and I was ready to start figuring by late afternoon.
Figuring is when the "final" touches are applied to the mirror. The transformation of a smooth sphere to a parabola can be a long process or it can be a short one.
Occasionally a message pops up on the Internet, in newsgroups, etc which goes something like "How Hard is it to make your own mirror?"
Having completed 2 mirrors I can honestly say, "it's not very hard" BUT, there are a few "if, and or buts" included.
Here are a few:
1. Take your time. If you rush, you may end with lots of errors.
2. Keep your area clean.
3. Enjoy the process.
Back to figuring, using CeO you really don't creep up on the final figure. In my case, I had a "very nice" sphere, so the transition was quite short when compared to when I used rouge on my first mirror.
There were some people that appeared to be rushing through things and they spent 3 times as much time finishing.
So how did my mirror end up? It has an "excellent, smooth parabola" but, L I have a turned down edge that is about a 1/8 in from the edge.
As I mentioned, it was a great weekend.
The Delmarva Stargazers are a great group of people, Thank You Don and Company.
The food was excellent.
Steve and Bruce Swayze were outstanding teachers, tutors and testers! A big Thank You goes to them too.
Enjoy the Sky
Ed "Grinder of Mirrors" Witkowski
More from Ed Witkowski
From the ATM List:
John Hutto .... subject: Re: ATM Delmarva Mirror madness
I would also like to thank Don Surles, Steve and Bruce Swayze and all of the other attendees who helped newbies like me make a mirror.
I could have never learned all that I learned that weekned if I had just "struck out on my own".
It was well worth the drive and time to attend, and the food was great!
These guys are a first class bunch for sure!
I am looking forward to having my 8" f/6 coated and assembled into a scope.
I think that I have the necessary knowledge to go it alone for the next project.
Aart Olsen on 03/09/2002 04:59:49 PM To: Don R Surles/AE/DuPont@DuPont cc: Subject: Mid-Atlantic Mirror Making Seminar Don, I'm writing to thank you for the warm hospitality you and the Delmarva Star Gazers offered to the attendees of last weekend's mirror making workshop. I had a great time and thanks to you and the other experts there I even ended up with a good eight inch mirror at the end. It's amazing to me how the company of a few good people can so quickly clear up years of reading about the black magic that optical work always seemed to be. You're right when you say that doing this is quite a bit different from reading about it, and for me it was a very enjoyable time indeed. Please extend my heartfelt appreciation to everyone who worked so hard to put it all together. You didn't solicit specific feedback from us after the workshop and I won't offer any here, but if you'd like to hear the opinions of the attendees let us know. Perhaps it'll make the next one even better. I hope to see you guys up the next time I'm in the neighborhood. All the best to you, Aart -- Aart M. Olsen mailto:firstname.lastname@example.org 217-244-4688 Library Systems Office Univ of Illinois Urbana-Champaign
To: Don R Surles/AE/DuPont@DuPont
Subject: RE: Solar Prominence Scopes
My solar prominence scope saw first light on Sunday and it worked like a champ! I ordered and received some rings and a dovetail plate from Ken Dauzat of Ken's Rings and Telescope Accessories ( I highly recommend his products - he does first class work!) and set the scope up on Sunday despite very hazy skies. I wanted to test the setup and thought that I might get lucky and catch a piece of clear sky. Well get lucky, I did. After about an hour, the sky clear substantially and I was able to view several nice prominences. Over a 20 minute period, I watched one prominence start out like a vase of flowers, then grow into a high-arching hook. Only a prior commitment kept me from spending the day enjoying my scope.
My thanks again to Dave for all his excellent work as well as you and the many others that contributed to making that weekend great fun!
p.s. - I'm debating whether or not to paint the scope. There's something charming about looking at it in it's raw state. And I think it might be fun to watch people's surprise when they look through the scope at the quality view after seeing a "Grits" container on the end of it with a "Richfood Grits" label on the outside. ;)