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12" Dob, How light before instability?
Assuming you used the very best materials and design
available, how light could you make a field-assembleable 12" Dob before it simply would not stable enough in operation or have the ability to hold collimation? I've used/owned pretty much every commercial scope going, but I've not used Newtonians very much. -Rich |
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12" Dob, How light before instability?
Gary Wolanski built a 15" F5 dob that, including the mirror, weighs a
total of 40 pounds! I've looked through it and it is superb! Wayne Howell Photon Phlats Observatory Port Townsend, WA Rich wrote: Assuming you used the very best materials and design available, how light could you make a field-assembleable 12" Dob before it simply would not stable enough in operation or have the ability to hold collimation? I've used/owned pretty much every commercial scope going, but I've not used Newtonians very much. -Rich |
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12" Dob, How light before instability?
Wayne Howell wrote:
Gary Wolanski built a 15" F5 dob that, including the mirror, weighs a total of 40 pounds! I've looked through it and it is superb! My brother-in-law was telling me today about a 12.5 lb road bicycle he saw. Lots of carbon fiber and Ti. I figure if a bike can be made this light, the structure of a scope could easily, albeit expensively (the bike was $8k) be made this light and probably a lot lighter. If you got the big bucks talk to these guys: www.hextek.com for a mirror, or http://www.rfroyce.com/conical/ 14 lbs for a 12.5" conical mirror that won't be as expensive as honeycomb. Add 16 lbs of structure and you have a 30 lb scope. Here's an applicable site: http://www.tms-usa.com/grayarea/janes16/jane16.htm Shawn |
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12" Dob, How light before instability?
Stability is a function of design and good engineering and has little
to do with mass. Wide stance, low center of gravity, rigid structure are the objectives of good design, and light weight! Steve Oregon On Wed, 21 Dec 2005 19:22:41 -0500, Rich wrote: Assuming you used the very best materials and design available, how light could you make a field-assembleable 12" Dob before it simply would not stable enough in operation or have the ability to hold collimation? I've used/owned pretty much every commercial scope going, but I've not used Newtonians very much. -Rich |
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12" Dob, How light before instability?
Rich writes:
Assuming you used the very best materials and design available, how light could you make a field-assembleable 12" Dob before it simply would not stable enough in operation or have the ability to hold collimation? I rebuilt my 10" Dobsonian to cut weight and got down to 9kg (including finder scope and a full tichness primary mirror at about 5kg). That is without mount, as the whole point was to put it on my Vixen GP-DX equatorial mount for CCD imaging. I used wood and steel (but sparingly) so there is room for further weight reduction with more exotic material. However, although it does work for the intended purpose, is a borderline construction and I usually prefer my more compact 6" MAK. pej -- Per Erik Jorde |
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