Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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I have been pondering this project for almost a year now, and I think I have all the bugs worked out. My goal is to build a gem mounted 12" reflector that will image at F5 or F3 via a focal reducer.
Weight will be key to my project, as the mirror and cell will be around 17 lbs. My goal is a 12" that is in the range of 25 to 27 lbs. All materials will be aluminum with aluminum straight truss poles.
Here are 3 of my drawings that I have been working on. The first one is the back plate that the mirror will mount too. All three pieces will be made out of T6061 1\2" aluminum plate.
At the bottom of the picture is a 4" wide flat spot that will be mated to a 4" wide aluminum dove tail. It will fit the Losmandy style DT's and most likely be in the 24" long range.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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The next drawing shows the middle frame support. It will be mounted on the other end of the 24" DT. I figured that 95% of the total weight of the scope will be carried on the dove tail. The middle support will be "lightened" as much as possible in order to keep the weight down.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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The third photo shows the end opposite the mirror. This is where the camera will be mounted. A typical 12" secondary obstruction is about 2-7\8ths", but I will be able to reduce this to 2-3\4". Not alot of difference, but it's within the strength parameters to go smaller and that will help to get more light to the camera.
In this design the vanes will be machined in and will be perfectly aligned. The vane width will be 1\8" thick.
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Equipment Overload!
Kerry.
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jayscheuerle
Carpal Tunnel
Reged: 01/16/06
Posts: 2989
Loc: S. Philadelphia, PA
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Drawings on paper... 
I like it. - j
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12" Green Goblin (trusser w/Protstar secondary and OWL refigured primary)• 6" f/5 Eero2 ball-scope • 6" f/5 Frankenscope • Garrett Optical 10x50 binos • Edmund 8" yoke-mounted red-tube reflector • Edmund 6" GEQ red-tube reflector (on loan to Dad)
Gone, but with lessons learned:
Skyquest XT8 • NexSTar 8i • Eeroscope 6" f/5 ball(sacrifice was not in vain) • Vixen ED80sf • Edmund red-tube 4.25" f/10 • Edmund Astroscan
Facts are stubborn things.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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The overall outside diameter will be in the 16" range, with the I.D. being 14" for all three rings. The holes around the rings will be machined out to 3\4" diameter.
I should have a sample of the front camera mount ring machined out of 1\2" black plastic so I can "cheaply" check my design before I start cutting up alot of aluminum. I'll post some pictures of it when I'm done in the next day or two.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Quote:
Drawings on paper...
I like it. - j
Thanks Jay.
I usually don't do drawings, but the MultiCam milling machine seems to want precise dimensions to be programed into it. Plus it helps to visualize the size of the project and to make needed adjustments.
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Equipment Overload!
Kerry.
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6006
Loc: Bremerton Washington
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Interesting idea Kerry.... 
I wish I could make telescopes..... 
Need any help?
Rob
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www.goldmtobservingcenter.com
Providing a great place for amateur astronomers, and ATM's to come and enjoy their hobby.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Quote:
I wish I could make telescopes.....
Give it time Rob, it'll come to you.
Quote:
Need any help?
Rob
I'll probably be over to use your lathe.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Well I was able to get the sample cut today and it looks pretty good so far. It's the same thickness as what the end result would be and same dimensions. This piece is where the camera will mount too.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Here is a close up of the front ring on the scope.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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I propped up this shot, to show how the camera will mount on the front of the scope. There won't be any other obstructions like a secondary mirror, just the light from the mirror reflecting straight onto the camera's CCD chip.
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Equipment Overload!
Kerry.
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BWAZ
sage
Reged: 11/21/05
Posts: 412
Loc: Sunnyvale, CA
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Sounds like a fun project. 
Just curious, what GEM mount are you going to use?
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10" f5 ATM Dob
NP101,
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6006
Loc: Bremerton Washington
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OK...now that is cool. I hovel at your feet.. 
I had one of those in planning stages as well. till I got freeky about mirrors.
Rob(now if I could just get good at it)
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www.goldmtobservingcenter.com
Providing a great place for amateur astronomers, and ATM's to come and enjoy their hobby.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Here is a shot of the MultiCam high speed router\milling machine. Horizontal and vertical milling only. Just under the table surface is a large vacuum chamber with the surface being slightly porus. Just lay a piece of material on top and the vacuum will suck it to the table and thats what holds it while the milling is taking place. The rest of the table top gets a sheet of thin plastic to increase the vacuum to the part being milled.
It will cut plastic, wood and aluminum only. I can't remember for sure, but I believe it's speed is around 75,000 RPM.
Estimated time for routing the aluminum is around one hour per piece. One quarter the time for any plastic or wood parts.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Quote:
Just curious, what GEM mount are you going to use?
I'll use the Atlas. Thats why I'm keeping the weight down.
90% of the weight should be directly over the Atlas head, similar to a 12" SCT, (only the weight will be 22 lbs.) but with only a few extra pounds hanging off the front.
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Equipment Overload!
Kerry.
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6006
Loc: Bremerton Washington
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Quote:
Here is a shot of the MultiCam high speed router\milling machine. Horizontal and vertical milling only. Just under the table surface is a large vacuum chamber with the surface being slightly porus. Just lay a piece of material on top and the vacuum will suck it to the table and thats what holds it while the milling is taking place. The rest of the table top gets a sheet of thin plastic to increase the vacuum to the part being milled.
It will cut plastic, wood and aluminum only. I can't remember for sure, but I believe it's speed is around 75,000 RPM.
Estimated time for routing the aluminum is around one hour per piece. One quarter the time for any plastic or wood parts.
You sure know more people then I do....Oh wait....You drive places.. 
I haven't left my place in years...
I am very impressed with your new scope.
Good luck, and fun.
Rob
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www.goldmtobservingcenter.com
Providing a great place for amateur astronomers, and ATM's to come and enjoy their hobby.
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ZielkeNightsky
sage
Reged: 10/01/06
Posts: 230
Loc: Denmark
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Nice project, i've just started a similar project with a 10" F/4 for my MallinCam.
How to you plan to bring the camera into focus? I haven't come up with a good idea yet.
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Lars
10", 8", 4" Newton
80mm Scopos
4" Achro
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Quote:
Nice project, i've just started a similar project with a 10" F/4 for my MallinCam.
How to you plan to bring the camera into focus? I haven't come up with a good idea yet.
Lars,
I have a 40:1 focuser that I'll be using. It has T-threads on one end and a 2" adapter on the other end. Total focus travel is around a 1\2".
The photo shows it on the left, I also have a T to C adapter to couple the camera to it or a T to 1.25" adapter that will use a standard 1.25" nose piece to couple the two together.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Here is another shot and closer, of the milling head. It's getting ready to mill out one of the rings for the scope.
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Equipment Overload!
Kerry.
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5745
Loc: Seattle Washington
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Last night I was able to get a rough cut\shape for the Losmandy style dove tail I will be using.
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Equipment Overload!
Kerry.
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