That does happen with plate glass mirrors. It can take several hours for the mirror temperature to stabilize after a figuring session. It happend on my 400...
Guido, greetings from California. What is the focal length of your 25 cm mirror? What kind of glass are you using? Did you check the annealing of your glass...
hi richard greetings from belgium the 25 cm have a focal length of F6 it is duran 50 glass the thikness is 6cm about 2.5 inch. im waiting 4 hours to testing.im...
I think that four hours is enough time for duran to reach thermal equilibrium. In fact, I work with plate glass, and I only wait one hour. If there is a...
... Pyrex shape it is about 1/3 times as dependent on temperature as plate glass. Also: A 3/4" thick piece of float glass will take only 8 minutes (!) to get...
Hurray Yesterday was a golden day for the project. Taking advantage of a break in clouds we,self and Arun Dolke, pointed the telescope to Jupiter which was...
Thanks Ken I could not have reached this stage without the support from you, Jim Burrows, Jerry, Guy and all the members of the list on whom I could depend...
After all this time, did you ever think that you'd be the guru on something like this? BTW, when you have finished a mirror, you can tell the machinists that...
In TM magazine #2, Robert Sigler Published an article describing the optical design for an all-spherical relay Cassegrain telescope. As I find myself...
I wish to thank those who responded off list to my request for help in locating information on the article in TM#2. I have obtained a copy of the article, and...
Greetings All, After reading all the discussions on the Millies-Lacroix criteria, I thought I would include this method into FigureXP. Hopefully this will...
... James: I'm not entirely sure why you want both an M-L and a transverse aberration analysis in Figure since they tell you essentially the same thing. But if...
I like the idea assembling OTA from parts. I think to start such a business in Israel, but I cannot find suppliers here. I'm not enthusiastic of accepting...
You can't find woodworkers around there? I would expect that there would be a lot of them about. Also foundry work helps for those designs that need to have...
Bob, on your web site you refer to willbell.com, are they supply complete ATM kits or ready optics/mechanics parts, too? I not want to spend much time into...
Greetings All, I've been experimenting with my Elgin-style grinding machine and have polished a nice sphere and edge a few times to date. I've been ...
William Bell supplies mirror making supplies in addition to all of the books (best astronomically orientated book store around) that they sell. Go look at a...
John If your machine only moves in 2 axis it may be difficult to figure with a sub aperture tool because the tool edge always hits the same zone. You may be...
anybody out there know of a circuit and drive system that would swing a solar array to follow the sun throughout the day? I like to use used C band sattelite...
John: We do all of our figuring by machine. I may be able to give you some pointers. What kind of offsets can you make with your pin. I assume you can offset...
Thanks Ron and James for replying, Ron I don't think I could attempt MOT work because the glass is alittle less than an inch thin plate glass. I have been cold...
I've seen most of these kinds of problems before so I created some additional degrees of freedom by mounting the overarm on an eccentric. Now I can even do the...
Probably the easiest is the dual photodiode setup where you balance the outputs of two photodiodes against each other and drive the telescope so that they...
... You should let the lap reach room temperature before beginning work. Depending on how warm you get the lap it may still be pretty soft after just 5...
... on it's ... James,Thanks for the figuring procedure, I was anxious to try put correction to the outer portion of my mirror so I followed your advice...
... Glad to hear that this is working for you. I performed ... It sounds like you've reached the point where the 8" tool is stalling out in terms of center...
... or other ... the lap ... channels/facets for ... James, I've posted a new photo under "John A's" photos in this group,it is of the 8" lap I've been using....
