The Cruxis Mirror Edge Support Calculator shows that two-point mirror edge support performs nearly as well as a 180 degree cable sling, with similar degrees of...
It is much easier and better to make supports that support the mirror exactly at the COG plane then making the 'line supports' you suggest, because for such...
Jan is spot on. With a cylinder support, how can you guarantee that the support is perfectly distributed over the thickness of the mirror? Take into account...
Hey everyone. I have acquired some PTFE strips 1/8" thick x 1" wide x 9 ft long. I can cut these into any length you desire. And if you need 3/4" wide, I...
As for edge supports, having tried many systems, including cable slings, I now use 2 ball bearings, the axis of which is horizontal. In this case, the contact...
Another solution is to place the supports on the part of the mirror cell that moves with the mirror when collimating. They will always stay in place that way....
... Yes, I built a 13.1" mirror cell that does exactly that also. Here is the key motivation for this question: sandwich mirrors. Hubble Optics or Normand...
I just unboxed the newly arrived Hubble Optics 18" mirror and find that the bottom mirror disk is smaller than the top disk. It the top is 18", then the...
If a support at the COG is impossible, you can directly support the edge of the front and back plate if you make sure that the load is correctly distributed...
Carey, ... cylindrical supports, would seem to support mirrors quite accurately for the tests to be useful. There have been many very good replies already....
I just did an interferometry test on an 18 inch HO mirror and I was worried about how to support it on the test stand. Turns out the mirror had much more...
Do you know the exact focal length? That would tell us if it was the same mirror. It doesn't matter is this particular mirror is not up to snuff (I'll be...
For Hubble Optics mirrors or similar ones with 2 plates, the best is to make two vertical weefle-trees. For each weefle tree, put 2 rollers or ball bearings,...
Thanks - I think the vertical whiffle tree you refer to is the same as the pivot arm scheme I was beginning to settle on. A pivoting arm, with pivoting...
I just did a check of refiguring prices - and even if I had the mirror refigured by Steve Swayze (which in my book makes it premium) the combined cost of the...
Yep. I bought a 16" HO and had it refigured to premium (0.97 strehl) and took care of the turned down edges etc. HO price plus refiguring was about 1/2 (HO...
3683 mm give or take 10mm. I forgot to get the exact ROC during Foucault testing. I would have gone back except the astig and surface roughness were the...
Tony at Owl Optics. Apparently the Hubble sandwich mirrors are harder than normal to refigure for various reasons attributed to the sandwich structure. So...
The label on the box says 71.39", which would correspond to 3627mm, so I would say not. One can discount their "S-Ratio" but I think their F.L. is likely...
That would seem worth it, however, how good is the substrate on these HO mirrors I wonder? I have no idea, but just curious whether it really is worth doing...
I have a 14" that I'm happy with. My 16 that was refigured tested excellent, but I haven't installed it yet. I have high expectations though... Tim in...
I will post an account of what I find, and what happens to this mirror regardless of how it turns out to do my part to avoid sampling bias (perhaps bad mirrors...
Hi I'm thinking about getting a 25+ inch dob but one topic that I can't find much info on is the process of installing the heavy mirror into the mirror box. ...
Hi Denis, You didn't mention the thickness you plan to have, but if it is 2", then a 25" mirror will be heavy (F/5 Pyrex is 73 lbs.). I have a 20" F/5 mirror,...
Hi there When I clean my 25" mirror , yes it is a 2 person job , there is room but mirror should be on a small angle . And I have one rule , it doesn't matter...
I have the 25 Obsession. The last time its mirror was lowered into the box, it was fairly easy for two of us, clearance was no problem. You can make a net of...
I don't lower my mirrors into any mirror box. My mirrors are installed in the mirror cell while it is outside of the mirror box. Once installed in the cell,...
