RASC-TC Thin Meniscus Mirrors

[@justinscarrow7223]

This was an awesome talk by Tom. I too was drawn to these mirrors because of Mel's 13" Zip Dob, but he unfortunately doesn't make any video content. Being able to hear this described from a different perspective (with a Q&A) really helps to put all the pieces together. Many thanks to Mr. Otvos, the RASC, and Mr. Bartels.

[@TomOtvos]

Apologies to all the commenters...I had no idea RASC peeled this talk out to a separate video.

[@TomOtvos]

@@TimK-1971 Thank you. Be sure to watch the companion video recorded about two months ago.

[@mystamo]

Hi Tom. I was following this project when you first started it on the form. I was discouraged when I showed off my glass and folks told me it was too thin. Any way to connect. I still have my glass and I would love to recreate the project.

[@TomOtvos]

@@mystamo How thin is thin? And I am not sure I understand part of your comment: are you asking how to connect with me?

[@mystamo]

@@TomOtvos Hi Tom! Yes I would love to know how to connect! I'm in the GTA and have my own kiln with ramp functions. The glass is a port hole 17" by 3/4" Appox.

[@TomOtvos]

@@mystamo That is thick for thin mirrors! You can reach me at first.last on Gmail.

[@danbuffington75]

37:10 "What about coma?"

[@travismiller5548]

lid elements in the kiln for extra points

[@myflyer813]

not just a question of saving money, it's also the experience building your own mirror on a different way... does the thickness of mirror allows just using mirror on top and wich kind of design is used in the mirror cell?

[@TomOtvos]

The mirror cell is a very simple 9-point affair, with two support posts 90-degrees apart.

[@travismiller5548]

11:53 Holy crap, all my homemade kiln controllers look exactly the same. same fuji pxr controllers, same exact plastic enclosure 🤣

[@keerthi-kiran]

How do you support these mirrors while grinding and polishing?

[@TomOtvos]

You make a plaster or hydro stone cast of the back of the mirror, to prevent flexing. Frankly, for a lot of my work, I just used one of those styrofoam rings that you can get at Michaels to do decorative wreaths, with reversed Gorilla tape to keep it from slipping. For polishing (and figuring) the mirror is on top.

[@stuwilliams3035]

Sorry if I missed it, but what considerations are there for the mirror cell of a meniscus vs regular mirror?

[@stargazer2042]

Stu Williams Mel says not many points are needed, but other experts say you should base it on the total thickness.

[@stuwilliams3035]

Star Gazer A flat bottom is intuitive to me with a classic mirror cell flotation system but a curved back with that system doesn’t seem intuitive to me, obviously I would trust Mel Without hesitation it’s just frustrating to resolve in my small brain

[@TomOtvos]

The mirror cell is a simple 9-point affair (to repeat a comment above). Three triangles with three support points each, that tip to accommodate the curvature of the back. The mirror is also supported from the bottom by two posts separated by 90 degrees.

[@burlbark]

Is altazinitiative dead? There has been no update on the website in some time now.

[@stargazer2042]

People are building thin meniscus mirrors still. They cool faster.

[@kdanagger6894]

Yahoo groups is going the way of the dodo bird. Many groups like that one are or will migrate to groups.io

[@TomOtvos]

No, AltAz Initiative is not dead. The people involved in it just talk to each other in a different way (primarily groups.io).

[@stargazer2042]

perlite. garden section. thanks.

[@marklimbrick]

As soon as the guy starts talking about the meniscus being stiffer because it is like a cone, I know he is not an engineer. Maybe in real life it is his job, but obsessions don't invite critical thinking. Mirrors are thick because they get the job done. Thick and honeycomb or solid.

[@Strutingeagle]

P = proportional ya big goof.