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5u4
member
Reged: 04/27/06
Posts: 92
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Bought a used 5" DGM OA reflector & need to re-mount the primary mirror (among other things due to minor shipping damage) to its plastic (PVC?) cell. The mirror was mounted with 3 strips of double face foam tape. Has anyone else used double face tape to mount a small mirror before?
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Art Bianconi
Post Laureate
Reged: 03/06/06
Posts: 4659
Loc: Delaware River Valley, New Jer...
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I once was stunned to see a Coulter large aperture mirror held to 3 pieces of wood with double stick tape. The small pieces of wood were glued to a piece of particle board!
Other, more experienced ATM's, saw the look of astonishment on my face and were quick to quip:
"Art. . . . don't laugh. it works!"
It may have worked but most CN'ers who address this question use 3 daubs of silicone, placed about 120 degrees apart, at 70% of the mirrors diameter.
If you place some popsical sticks in between the silicon daubs, they will keep the mirror elevated above the backboard just a whee bit.
After the silicone has cured, slip out the sticks and the mirror will stay elevated.
Silicone is tenacious when cured. Three daubs, the size of a nickle, will hold a 5" mirror, no sweat. Just be certain that both surfaces are clean before application.
Art
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“Everything is on its way to somewhere. . . . . everything!"
____________________ George Malley (John Travolta)
________________________ "Phenomenon"
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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As you know your DGM 5" uses an off axis parabolic mirror. You need to be able to make rotational adjustments to the mirror to get the optical axis pointing correctly. I would be careful using any method that makes it difficult to quickly make rotation adjustments to.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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5u4
member
Reged: 04/27/06
Posts: 92
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Thanks, going to go with the 3 silicone globs. Used this in the past with a 4.25" Schief mirror & it worked fine. Also allows slight movement of the mirror before the silicone drys, to make sure it's centered, etc.
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