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  #1  
Old 25-02-2010, 11:22 AM
mbaddah (Mo)
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Anyone build ultra-compact dobs Tectron style?

Anyone know of any other manufacturer who builds dobs this compact?

http://www.tomclarkbooks.com/tomclar...Dobsonian.html

The 8" would make such a fantastic grab-n-go scope And it has Zambuto optics! Unfortunately Tom isn't manufacturing these dobs anymore and neither does he ship to Australia
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  #2  
Old 25-02-2010, 12:11 PM
Wavytone
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I recall seeing a 14" made like that in the late 1980's, from memory Wayne Stuart built it.

The top end fitted in the bottom and with both in the rocker box it was an easy fit in the boot of a car as small as a Honda Civic, with ample room left over for the truss poles.
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Old 25-02-2010, 08:28 PM
mbaddah (Mo)
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The starmaster upper truss fits snuggly in the rockerbox

http://www.starmastertelescopes.com/...scopespecs.htm

anyone know if the obsession/sdm are the same as well?
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  #4  
Old 25-02-2010, 10:30 PM
ausastronomer (John Bambury)
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Hi,

The Starmaster and Tectron both use a similar design whereby the UCA nests into the mirror box. The Starmaster also uses a whiffletree mirror cell where the mirror and cell come out of the telescope for transportion.

The SDM scopes are based on the Obsession design (Kriege) and the UCA cannot nest into the rocker box. The mirror should also be transported "in the telescope". The mirror cell is designed for this.

There are arguments in favour of both designs.

The major difference is the Obsession uses outboard mounting of the truss poles, where the Starmaster uses inboard mounting of the truss poles. While this design enables you to nest the UCA inside the mirror box, it unfortunately necessitates the mirror box and the rocker box be designed physically a lot larger for a given aperture of telescope. They may look small in the pictures but they are larger and heavier for an equivalent aperture than the Obsession design, by about 10% to 15%. ie a 15" Obsession is smaller and lighter than a 14" Starmaster. Another negative, for me anyway, of the Starmaster design is I dont like fiddling with truss poles and pole clamp hardware inside the mirror box right above the mirror in the dark.

I have used both designs and prefer the Obsession design, notwithstanding the UCA does not nest into the mirror box..

Cheers,
John B
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  #5  
Old 25-02-2010, 11:19 PM
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astroron (Ron)
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Here are some pics of how my 16"Scope is designed, mostly on the Kriegie style
Cheers
Attached Thumbnails
Click for full-size image (Truss connections.JPG)
79.7 KB38 views
Click for full-size image (UTA in Rocker Box.JPG)
125.2 KB39 views
Click for full-size image (Upper tube connections.JPG)
74.1 KB39 views
Click for full-size image (16 inch in car.JPG)
198.0 KB40 views
Click for full-size image (Trusses.JPG)
91.6 KB37 views
Click for full-size image (Folded Trusses.JPG)
90.2 KB35 views
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  #6  
Old 26-02-2010, 06:49 AM
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GrahamL
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Somone here was making something similar a while back , not in any numbers or really advertiseing the fact , the scopes looked great , hopefully someone will chime in regarding who it was .. I can't remember .
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  #7  
Old 26-02-2010, 03:20 PM
mbaddah (Mo)
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Quote:
Originally Posted by ausastronomer View Post
Hi,

The Starmaster and Tectron both use a similar design whereby the UCA nests into the mirror box. The Starmaster also uses a whiffletree mirror cell where the mirror and cell come out of the telescope for transportion.

The SDM scopes are based on the Obsession design (Kriege) and the UCA cannot nest into the rocker box. The mirror should also be transported "in the telescope". The mirror cell is designed for this.

There are arguments in favour of both designs.

The major difference is the Obsession uses outboard mounting of the truss poles, where the Starmaster uses inboard mounting of the truss poles. While this design enables you to nest the UCA inside the mirror box, it unfortunately necessitates the mirror box and the rocker box be designed physically a lot larger for a given aperture of telescope. They may look small in the pictures but they are larger and heavier for an equivalent aperture than the Obsession design, by about 10% to 15%. ie a 15" Obsession is smaller and lighter than a 14" Starmaster. Another negative, for me anyway, of the Starmaster design is I dont like fiddling with truss poles and pole clamp hardware inside the mirror box right above the mirror in the dark.

I have used both designs and prefer the Obsession design, notwithstanding the UCA does not nest into the mirror box..

Cheers,
John B
Thanks for that John very informative indeed. Doesn't sound like the best thing to try and install/remove the trusses near the mirrors!

btw your SDM#33 is beautiful My next scope may be something similar to that
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  #8  
Old 28-02-2010, 12:44 AM
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Waxing_Gibbous (Peter)
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Ugggnnh!
More plywood! Might as well build a television out of marsh grass!

There is a Canadian company called Genstar, that does a 10" , with various optics, that's amde out of Alumin(i)um. Its even MORE compact and a WHOLE lot lighter, for about $2500 AU.
The catch is, they won't be making any more until July or August while they relocate.
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  #9  
Old 28-02-2010, 01:15 AM
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astroron (Ron)
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[QUOTE=mbaddah;563839]Thanks for that John very informative indeed. Doesn't sound like the best thing to try and install/remove the trusses near the mirrors!

Do As I Do, and leave the Cover on until you have installed the Trusses
See photo in post #5 in this thread
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  #10  
Old 03-03-2010, 09:39 PM
mbaddah (Mo)
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Some guy here built a 10" dob that fold into a suitcase, amazing!

http://www.cloudynights.com/ubbthrea...l/fpart/1/vc/1

And here...

http://www.cloudynights.com/ubbthrea.../o/all/fpart/1
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