Well, in spite of being under the weather, I took a little time this afternoon to make a new tool for the donated 8" mirror. I have a few photos I think Tom T. will appreciate. But, let me get a little more into what I did (beyond what the photos show.) First, we decided to grind this mirror ( now an f/8) to a faster mirror. We are targeting f/5 but I hope we can get a little feedback from Javier as to what f/ratio he would like this to be. I want to just say this now. I am hoping that this will be Javier's scope one day. There I said it. We can discuss this all later. For now, let me tell you what we have. We have a almost polished 8" mirror, a tool covered with pitch and lots of ugly rouge that covered everything. Today, I went down to the lab with the idea in mind of preparing the tiles to cover the new tool.
Now, this is interesting- we usually grind the edge of the mirror-to-be with a sharpening stone. I takes forever to do this, but it turns out really nice. We want to achieve a 2-3mm bevel. (I removed pitch last night from the tool). Today, I decided to try an experiment using a diamond disc in the lab to grind this bevel. I used our tool to see how it would work. It worked magnificently! Actually, I'd like to try this technique in the future on Pyrex. Next, I have a lttle kit in the lab to acid etch crowns and veneers. I thought , " what the heck, let's give it a try." So, before I applied the etching liquid, I sandblasted the surface ot the tool and all the ugly stuff around the edges. You will see this in the photos I hope. I trimmed up the piece of ceramic tile I set aside for this tool. You have to score it with a disc and then use nippers to trim it to size. Then using another fine stone in the hand piece, I trimmed to my liking the outer edges.
Getting home, I had all the stuff ready to go. I used a two part epoxy to attach the tile. The idea was to get the epoxy mixed up and coat the tool then stick the tile to the surface. But before I did this, I was "clever C..." and leveled the work table. This is so the tile and epoxy wouldn't all fall to the low side. Tom W. who is one of my mentors in all things scopes and mirrors, told me to set the mirror on top of the tile to marry the couple together as close to the "dish" as possible. I used wax paper (all I had) to place between the new tool and mirror so they wouldn't accidentally bond themselves together. All things went well actually and I even took some masking tape and applied it to the edges of the two discs so they wouldn't slip. I do believe though I got too much epoxy in some places and not as much in other places. So I took the equivalent of a toothpick and moved it around to my liking. You can see some of the residual epoxy on the surface of the tiles.
Hope you all enjoyed this. It was really intended to inform those that wan to use this either to understand the process, comment on the actual process, or even to use it in the upcoming July event.
One last comment. I am actually thinking of using this mirror and tool in the upcoming Tinkerer's Fest. It will make those hours of mating the surfaces together much shorter (how about that Jerry?).
T
P.S. The photos are not labeled, so if you have questions on which is which, just ask me. [more photos posted at
https://secure.flickr.com/photos/27241501@N03/sets/72157634222053744/ ]
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