I have an 8 inch f/10 mirror that is captive in its cell with silicon. The mirror has what appears to be astigmatism but only sometimes like, when its warm but not when its cold. Do you think the silicon adhesive would cause this ? The mirror is stuck onto the entire surface of the cell and has no gap to support cutting it off. So there are two questions here. Could the silicon grip the mirror to tightly "deform ing its figure" and how can I remove it without damaging the mirror ? BTW, I did not do this to the mirror, I bought it this way from another party.
Siliconed Mirror
Started by imgary, 07/22/2003 06:10PM
Posted 07/22/2003 06:10PM
Opening Post
Posted 07/22/2003 06:12PM
#1
Possibly the mirror is so confined that it can not expand equally and could cause it to deform. But maybe it is just the mirror or the glass it is made from to blame.
[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue
Amateur Imager
Posted 07/22/2003 06:26PM
#2
The cell is cooling before the mirror does. As a result it's 'tugging' on your mirror until the mirror and cell are both the same temperature.
Posted 07/22/2003 06:50PM
#3
add to my prior post.
As long as the mirror is kept cold it works fine. If it warms it becomes really bad. Its kept outside covered in the shade so its almost always at the outside tempature. So, in the winter it works great. In the summer it does not. I must have gotten a winter only mirror! Strange, I feel it must be the adhesive, now to remove it, it will be difficult
As long as the mirror is kept cold it works fine. If it warms it becomes really bad. Its kept outside covered in the shade so its almost always at the outside tempature. So, in the winter it works great. In the summer it does not. I must have gotten a winter only mirror! Strange, I feel it must be the adhesive, now to remove it, it will be difficult
Posted 07/22/2003 06:50PM
#4
Yes. Cut/saw through it with a thin wire. If you must use silicone to secure a mirror, use 3 "dollops" and use separators so that the dollops have height and flexibility side-to-side when they are cured. If the mirror cell has clips to hold the mirror in, don't glue it down at all. If it is clipless, then you'll have to figure out the best way to go based on its design and the requirements of the mount. For example, in my clipless mirror cell in Dob-mounted Newt, I just have a short velcro strap screwed into the top post (just made this mod last week from a different approach). It mates with velcro on the mirror side to prevent the mirror from flipping out of the cell if the scope goes horizontal, and I don't turn my Dob-mounted scopes upside down.
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Mike
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Mike
Posted 07/22/2003 09:06PM
#5
Gary, I had almost exactly the same thing happen once. The mirror cell I had made from wood (1/2" ply) was too thin so I remade with 3/4". Once I remounted the mirror everything was fine.
I used a hacksaw blade to saw the mirror from the silicone globs. I understand your situation is a little different. I believe the wire approach, or even strong monofilament fishing line, will be the best approach in your case.
Walt
I used a hacksaw blade to saw the mirror from the silicone globs. I understand your situation is a little different. I believe the wire approach, or even strong monofilament fishing line, will be the best approach in your case.
Walt
Funding Member
