Beri
sage
Reged: 06/29/05
Posts: 275
Loc: Croatia
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A funny little 110mm / F5.2
300 mm F4.8 dob
150 mm F10.8 EQ newt
Lots of small dobsonians for an educational project
Binocular tripod
Binocular paralelogram
200 mm F6 Dob
80 mm F5 refractor
Another one for a young astronomer
114 mm F10
150 mm F8 for a local school
My first one, still in everynight use,
114 mm F8 made out of Surplushed mirrors
Two red-black dobsonians made for a good friend
a 250 mm F5 and 170 mm F5.2
There is probably more but cant find any pictures right now 
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15x70 Binoculars
no scope right now
http://www.scopemaking.net
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6190
Loc: Bremerton Washington
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Quote:
In my experience, the two strut is very stable.
The poles are quite stout - 2" diameter and .065 wall thickness, that helps a great deal. The nature of the clamps helps some too.
I get a small movement of the laser collimator's dot as I move through range of altitude motion - maybe an eighth of an inch, nothing of concern and nothing that causes any noticeable image issues.
As to ease of construction, it does simplify things a great deal. Simple focuser board instead of a cage and simple clamping mechanism are the main advantages.
Thanks for the interest
I like the design, and you executed it very well... 
The simplistic approach makes this design a real winner in my book. Plus the short FL gives added rigidity to the whole system.
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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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6190
Loc: Bremerton Washington
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Holy leapin Hornied toads Lois Lane......
You have been a busy scope builder.. 
I fully admire those who fine tune their skill in the art of reflector making.
Nice designs, nice clean lines, nice,nice,nice. 
I'm impressed..
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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theoUK
sage
Reged: 04/22/04
Posts: 234
Loc: N. Yorks, UK
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Hi,
its just friction against the shaft. The focusser tube (which is plastic plumbing pipe - I hope to replace with metal when I find some) rests against four bearings opposite the shaft. Compression is adjsuted with the long screw you can see on one pic that pushes the shaft and its bearings against the tube. The sahft support is not 'hinged' but the machine screw fixings have some give to achieve the pressure. Its a similar design to this: http://www.deep-sky.co.uk/tm8.htm but the compression screw is on the other side. BTW the whole thing is fixed to the back plate (the PVC tube I used had a base to it) with three adjustable bolts so it can be collimated.
Theo
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Vixen SP
TAL-150P
Surplus shed f5 travel scope
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RRavneberg
professor emeritus
Reged: 12/02/05
Posts: 634
Loc: Columbus, OH
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The two-truss design is very stable if built right. The "trick" is to pull the tubes into channels. With such an arrangement, they simply cannot move. Then, by using a large enough diameter tube you can reduce flexture to the point where it's insignificant. The principle is apparent in the attached image. The process works well, whether the track is on the outside of the mirror box (as in this example) or the inside.
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Ron Ravneberg
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RRavneberg
professor emeritus
Reged: 12/02/05
Posts: 634
Loc: Columbus, OH
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I have fairly detailed write-ups for the two telescopes shown here, and would be pleased to send PDF copies to anyone. Just contact me off list.
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Ron Ravneberg
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6190
Loc: Bremerton Washington
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Quote:
The two-truss design is very stable if built right. The "trick" is to pull the tubes into channels. With such an arrangement, they simply cannot move. Then, by using a large enough diameter tube you can reduce flexture to the point where it's insignificant. The principle is apparent in the attached image. The process works well, whether the track is on the outside of the mirror box (as in this example) or the inside.
Great application of a great design.
I like how you ran the dew heater wires through the tube.
Cool.. I assume.... 
Beautiful scopes.
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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rnabholz
scholastic sledgehammer
Reged: 07/25/04
Posts: 765
Loc: Iowa
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Here is another approach to the clamps using aluminum c-channel - Ron is right, they simply cannot move.
Ron, - Good to see you here - I read and reread your pages on Alice when looking to build my scope. I appreciate your work, and, even more, you sharing it with everyone.
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Rod Nabholz
Home Built Astronomy Projects
Wild Bird Photography
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Anonymous
Unregistered
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Art:
Bill Cheng's is looks like a little piece of art. I could only dream that mine will look a fraction as good.
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6190
Loc: Bremerton Washington
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Quote:
Here is another approach to the clamps using aluminum c-channel - Ron is right, they simply cannot move.
Ron, - Good to see you here - I read and reread your pages on Alice when looking to build my scope. I appreciate your work, and, even more, you sharing it with everyone.
Very nifty way to secure the truss.. 
Impressive, very impressive...
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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Anonymous
Unregistered
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Theo:
That scope turned out real nice, wish mine looked as good. I'm jealous of your focuser, mucho* good work.
*a little Spanish lingo there.
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Brian Reed
Vendor (Round Table Platforms)
Reged: 10/29/04
Posts: 378
Loc: North East Illinois
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Rod,
I'm thinking of remaking my 10 inch into something similar to yours. (trying to make it more travel friendly) Does the focuser board double as a mirror box cover?
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Brian
10-F5.6
8-F7
http://www.roundtableplatforms.com
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6190
Loc: Bremerton Washington
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I have hesitated in posting a picture of my scope/s that I built, or had a hand in building.
My scope is the large 6"f/15, and the 6"f/6.5.
The GEM was also homemade, as well as the hydraulic pier, and base. Even the hydraulic pump was homemade.
Many have seen my rig, and so I don't wish to drive it down your throats.
But for topics sake here it is again.
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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David N
member
Reged: 11/11/03
Posts: 85
Loc: Portland, OR
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8" F6 String Dob
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10" Orion Dob
8" LX200-C
8" String "Suitcase" Dob
20" String Dob
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RRavneberg
professor emeritus
Reged: 12/02/05
Posts: 634
Loc: Columbus, OH
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Quote:
Rod,
I'm thinking of remaking my 10 inch into something similar to yours. (trying to make it more travel friendly) Does the focuser board double as a mirror box cover?
Brian,
Rod? There are two Rons and one Rob posting to this thread. Not sure about a Rod. But I'll respond re. my scopes. The mirror box covers for both scopes are separate. Both focuser boards store inside their respective mirror boxes. Both mirror box covers are held in place with magnets. The 10" cover is set aside while observing; the 8" cover stores on the back of the scope and acts as a counterweight to help balance the scope (see attached image).
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Ron Ravneberg
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MMICKELS
Aluminum Knight
Reged: 01/20/04
Posts: 25451
Loc: The Land of Shake and Bake
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I love seeing all these well executed designs. This thread demonstates the individuality of ATM'ers!
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Mark
"Never eat more than you can lift"
Miss Piggy
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Art Bianconi
Post Laureate
Reged: 03/06/06
Posts: 4659
Loc: Delaware River Valley, New Jer...
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Dennis wrote: "I'm jealous of your focuser, mucho* good work."
Dennis, I just created a new String devoted exclusively to focusers others have made. Maybe we'll see the same excitement over there that we are seeing here with OTA's.
Art
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“Everything is on its way to somewhere. . . . . everything!"
____________________ George Malley (John Travolta)
________________________ "Phenomenon"
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Art Bianconi
Post Laureate
Reged: 03/06/06
Posts: 4659
Loc: Delaware River Valley, New Jer...
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Beri, that photo you posted of that 200 mm F6 Dob is lovely!
Might we see more detailed photos please? Could you also tell us what type of materials you used and perhaps some discussion on the building techniques?
Thanks!
Art
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“Everything is on its way to somewhere. . . . . everything!"
____________________ George Malley (John Travolta)
________________________ "Phenomenon"
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Chuck Fellows
sage
Reged: 08/21/05
Posts: 450
Loc: Cave Creek, Arizona
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Quote:
8" f/4.3
Ron Ravneberg, I loved your scope named Alice. Below is my rendition of Alice, if perhaps a bit more modest. I see all of your scopes have a great deal of attention to detail. Very nice work on all of them.
Chuck Fellows
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16" Truss DOB Swayze Mirror
7.1" Custom Mak Newt
Tools, Lots and Lots of Tools!
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Chuck Fellows
sage
Reged: 08/21/05
Posts: 450
Loc: Cave Creek, Arizona
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Here are a few of my scopes...
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16" Truss DOB Swayze Mirror
7.1" Custom Mak Newt
Tools, Lots and Lots of Tools!
Edited by Chuck Fellows (08/09/06 10:23 PM)
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