Following the success of my good mate Mental4Astro and his Odyssey II (now Odessius)rebuild. I have taken apart my 13.1" Odyssey and have started to build my own version of a truss scope. The first step was to strip the Odyssey of all its parts. The council pick up is on Tuesday.
Having assisted Mental4Astro's with his rebuild and picking his brains on many many occasions. I made some drawings and constructed a timber cutting list. My local timber yard supplied the 15mm plywood and cut my components for the princely sum $55. BARGAIN.
Gradually I'm building the mirror box. Mental4Astro helped me position the mirror on the base of the mirror box. Next I cut and glued my clamps. Fixed the holding nuts in the clamps. Cut some hex handles from the scrap ply to hold the bolt heads and glued them on. (Waiting for the glue to dry now).
Today I fixed the clamps inside my mirror box. Meanwhile I've been building my secondary mirror holder. Photos are attached.
Progress not as fast as I'd like but still coming along.
Completed the mirror box, transport poles and worked on spider.
Trimmed the hexagon on the spider so that the central obstruction is now totally due to the secondary mirror and spider vanes.
Mental4Astro again has given some excellent advice re size of secondary cage. Fixed the clamps to the secondary cage this afternoon and placed it on top of the transport poles. The image in the secondary mirror is the centre of the bottom of the mirror box which I deliberately didn't paint black. It was very reassuring to see this image. The spider is only tentatively placed on top of the secondary.
To offset or not to offset the secondary that is the question.
Have been working away steadily each day afterwork on the rebuild.
Laquered the secondary cage, completed the spider and attached it. Painted the black surfaces and started construction of the finder holder. Going to use a Celestron First Scope as a finder with a red dot finder attached as well.
Built the focuser board. Had lots of advice from Mental4Astro.
Last night Mental4Astro and I went to a park in Dover Heights to determine the pole length using his ingeniuos method.
Tonight after work I cut the poles with his pipe cutter. Many thanks mate! Then I had to have a try.
WOW! It works! Spent a few minutes collimating with laser and I'm stoked!
Still have altitude bearings, rocker box and ground board to go.
Think I'll call it Tantulus. The name "Tantalus" is the origin of the English verb "to tantalize". There are some other sinister references though to this name but I'll stick to tantalize.
Hope to have it ready for July new moon at the Katoomba airfield.
Have been working away steadily on the rebuild. Having a heavy cold and World Cup soccer on SBS hasn't help my motivation over the last two weeks but have meade significant progress in the last two days.
to my good mate mental4astro for all his advice and particularly his router which we used to cut my rocker box altitude bearings and seats.
The rocker box is now almost complete. Needs more lacquer and teflon attached.
Altitude bearings need to have laminate affixed. Having trouble sourcing suitable laminate. Don't really want to spend $120 for a sheet when I need two pieces 1m x 0.3m. Looks like I'll have to keep looking . If anybody has suggestions they'd be most welcome.
Was hoping to be ready this weekend and head out to Katoomba airfield but it looks like I'll not be ready.
Graham,
No I didn't think of iron on lamintes.
I've been looking for weeks. Yellow pages and net kept giving me kitchen showrooms when I needed a factory.
I visited a kitchen manufacturing place this afternoon and they had some offcuts. The receptionist took me to the cutting room and pointed me to a shelf 10 seconds was all it took to find what I needed. When I said that all I needed was a couple of 30mm wide strip a little over a metre long, she asked the tradesman to cut it for me. He obliged as the boss walked buy. I offered to pay for my strip and they said take it.
I fixed them to the bearings later this afternoon and am waiting for the adhesive to do its thing. I decided long ago to use a lazy susan bearing for the azimuth. It moves really smoothly at the moment. I can only hope it'll do the trick when the scope is finished.
Scope will be ready for first light by the middle of next week with any luck.
Quote:
Originally Posted by nightstalker
Have you checked out the iron on laminates Peter ?
Are these for the face view of your alt bearings or the running surface on the teflon pads ?
Thats great Peter , kitchen makers do usually have few bits and pieces
laying around I have a roll of iron on stuff but thought you were chaseing big pieces 1000x 300.
Seriously, I love that timber Peter! Well done. Better than I could ever, ever build. Seriously the secondary mirror holder is almost identical to my 6-inch Newt build 25 years ago - A good ol' piece of 1-inch dowel did the trick back then!
In Greek mythology, ambrosia was the sustenance of the gods. Some say that it was made of honey, water, fruit, cheese, olive oil and barley. In The Odyssey ambrosia has other uses, as in the present instance. Hermes' magic sandals, which enable him to fly, are referred to as "ambrosial".
Tantalus, who was condemned to eternal punishment for stealing ambrosia from the gods. (He was tantalized by lucious fruit always just out of reach.)
Looking through scopes is tantalising and everything we look at is out of reach.
It was wonderful to see Tantalus fully assembled, AND working, in my backyard this arvo. A very handsome scope too. The light coloured timber with its grain, the symetry of the poles, the geometry of the secondary cage with its novel spider- love it.
Its movements are silky smooth too. I'm surprised at how smooth the Lazy Susan azimuth bearing is too, without being too light or too heavy.
Tantalus had its first light tonight. Its 3" finder was equiped with the optic fider reticle eyepiece we made for it- works a treat. Its exposed secondary cage showed its need for a light baffel, easily solved too.
Tantalus is a kick-ass light bucket. So much easier to operate than its previous solid tube form. Oh, and now able to be completely collimated- no more comet tailed stars across the FOV, .
Sorry for re-opening this topic, but I've got a question about the trusses you've got. What is the diameter of it? I've would really want to build suck a telescope myself and I'm looking forward if you've got anything you came around this year what you want to change about it, to improve it.
Greetings from a Dutch guy, that's right, from the Netherlands
Luuk,
Hello Luuk,
My poles were 70mm diameter aluminium. I am very happy with them.
There are a couple of things I'd change if I was doing it again.
Setting Circles
1. I make allowance on the ground board for some azimuth setting circles this would help me locate objects somewhat.
2. I'd design a mechanism to allow installation of altitude setting circle.
3. To get the balance right with my planned bearings I had to add additional weight to the base of the mirror box. By careful design I could have a deeper mirror box and deeper rocker box this would add more timber to the construction making for a bigger package which would allow for the bearings to be smaller but higher up. Its a trade off.
The Kreige an Berry book "The Dobsonian Telescope" A practcical manual for building large aperture telescopes. Is highly recommended reading if you are embarking on building your own scope.
4. I am still amazed at my secondary mirror holder and how easy and cheap it was to make. (approx $15 not including the mirror). To by spider vanes alone for my secondary cage would have cost $100. If I had metal working skills then I'd have constructed it from metal. But it works fine.
I'm still looking further to a right design for my truss dobson. I want to use my mirror from my Skywatcher 8 inch and it's a F/6. So that isn't really ideal.
mate Mental4Astro and his Odyssey II (now Odessius)rebuild. I have taken apart my 13.1" Odyssey and have started to build my own version of a truss scope. The first step was to strip the Odyssey of all its parts. The council pick up is on Tuesday.
his brains on many many occasions. I made some drawings and constructed a timber cutting list. My local timber yard supplied the 15mm plywood and cut my components for the princely sum $55. BARGAIN.
the mirror box. Mental4Astro helped me position the mirror on the base of the mirror box. Next I cut and glued my clamps. Fixed the holding nuts in the clamps. Cut some hex handles from the scrap ply to hold the bolt heads and glued them on. (Waiting for the glue to dry now). 
the secondary cage, completed the spider and attached it. Painted the black surfaces and started construction of the finder holder. Going to use a Celestron First Scope
as a finder with a red dot finder attached as well.
from Mental4Astro.
method.
WOW!
soccer on SBS hasn't help my motivation over the last two weeks but have meade significant progress in the last two days.
to my good mate mental4astro for all his advice and particularly his router which we used to cut my rocker box altitude bearings and seats.
of iron on lamintes. 
looking for weeks. Yellow pages 
(Sorry
Thank you! 
