Hello Pierre, thank you, I do pass in Bourgogne sometimes (mostly when I'm driving towards the Provence), so maybe one day we can arrange a meeting. It would...
Hello, If it is possible, turn the mirror upside down. Be careful not to scratch it. Lay the box on top of it. Then, turn the mirror over. Another method would...
I have a "big" Dob. A Hardin 10 inch. I got the whim to go into amature astronomy last year on my 66th b/d, this month. I haven't had this scope out yet. It is...
Hope you won't consider this too off-topic. I have a new 24" and am looking for a used Sky Commander XP4 & encoders if you are looking to change your setup. ...
Dear all, I'm building a 706 mm f/3.1 newtonian. I prepared a facebook's page to describe it. It is in Italian, but the photographs are multilanguage ;-) Here...
Very nice ! Did you make the upper cage rings by rolling straight aluminum extrusion? If so, did you fill the extrusion with something like sand before...
Hi to the Group, I am from Hungary so I am sorry for my bad English. We build a 24" Dobsonian with a friend. We already have a home built 16" and 20" and want...
what stickness have you 1 inch 2 inch or 2 cm or 4 cm for mine I go to my dental place and asking him to make a grove unther whit it instrument like...
Sandor, I have glued my 500 gramm secondary to aluminum with only three dots of silicone. That will be enough for yours as well. The dots I use are about 1 cm...
Sandor, I also glued my 130 mm secondary (20 mm thick) with the silicon transparent type (for aquarium if I remember weel). To avoid any differential...
It's been a long journey, but finally the 1100 mm telescope with Lockwood optics has seen its first star light. An update with pictures is given on our web...
Robert, Congratulations on FINALLY getting your scope finished. I have felt bad for you for the last five years while you were waiting… Anyway, now it is...
Hi, relatively new, lurker here. So, a few months ago, I acquired this Obsession with a 3" thick, 30" f/5 Sitall primary (yes, it weighs a ton). While it...
The substrate is stable as temps change. It's that so-called "boundary layer" that would be problematic. So blowing that away would be ideal at least until...
Hello Jeff, I have always had temp issues living in New England. Temp moves all over the place. I have an 18" Obsession, so it isn't a direct comparison,...
Roger, When you say that it 'works quite well' what do you mean? I'm really not trying to put you on the spot or anything. I'd just like to know if there is...
Dick, Mirror temp drops to ambient quicker, IMO. Eliminates the possibility of a boundary layer during cool down. That is more feeling than measurable. No...
Understood. Then its more of a 'feeling' than anything quantifiable. I've never gotten to ambient with my 20". It is always a catch up sort of thing. I'm half...
I did write a bit about this earlier this year,,,,the cooling fans are terrific at removing the heat from the surface and creating a differential temperature,...
That is why I replaced my 18" 2" thick with a 1.6" thick. That in combo with fans, I can keep it about a degree above ambient. Which is very good compared to 5...
Cool,,, I keep hoping to find the right person to work with to get the design down to 1/2 inch thick, there should be some heat flow software somewhere that...
Thanks Walter, This has been my understanding for a number of years: that the center of the mass of the mirror has got to transfer its heat before ambient is...
My thoughts are to create a hexagon substructure. same thickness runners as the mirror. at the attachment point to the mirror surface glass the mold will...
I've worked with both thin and crated, or structured mirrors. They can work just fine if properly designed and supported. However, be careful regarding the...
I use the stock 18 point support system that comes with the Obsession Classic scopes. And I have upgraded to the Howie Glatter cable sling system. The mirror...
Roger, I let this msg. slip by me. Yeah, I bought one of his slings just after he made an announcement about them. I'm actually rather surprised that after all...
I realize there are costly devices based on actual wet-bulb T and sky T. As an engineer I know it is clearly less expensive to detect actual occurrence of dew...
