Thank you very much! I am glad to hear that!

Thanks, that means a lot!

Thanks! That's awesome, good luck on that!

Thank you so much!

Thanks!

Thank you!

Awesome, thank you!

Thanks so much!

Hi, Thanks! At the moment I don't have anything ready to put up on following up on this, as this mirror was finished way too quickly for anything useful to come out of it. Hopefully some time in the future i plan on finishing this up. I usually send my mirrors away to someone from my astronomy club who has facilities for coating. Cheers!

Thanks Douglas. Have been waiting to receive a new mirror blank for part 4, as this mirror having such a long focal ratio didn't tell you much about how to figure the mirror! Cheers

Thanks! At the end of polishing the mirror will be roughly spherical, and after figuring it will be a parabola. Cheers!

Me also bro. This series is really helpful

Hi, the mirror size is 8". The tool is smaller but i would probably reccommend using the same size tool for starting out. A smaller tool can give you more control over the mirror surface when figuring. Cheers!

Thanks for the suggestion! Will try and avoid problems like that in the future in the first place hopefully :)

In case you are still wondering: The glass has to be this thick in order to not deform under its own weight, i.e it needs to be rigid to stay very accurately curved. The easiest way to do this is by making it thick. There are ultralight mirrors but those are usually contained in very special mirror cells, are more expensive due to a different kind of glass being used, are not flat-back and are thus much more susceptible to warping due to temperature changes. This will end your observing session immediately if you have no way to cool the mirror without inducing air turbulences. heres the basic process of making the actual mirror surface. There are 2 ways to achieve this. One is Silvering and the other one is Aluminizing. You can only do Silvering at home. Aluminizing is a whole different level and cant be done at home, at least not without extensive knowledge, precision and hundreds of thousands of dollars worth in machines. What you want to do is Silvering. Basically you spray or pour 2 solutions on to the polished mirror blank in precise equal amounts and it becomes metallic silver depositing on the surface. These solutions consist of: Distilled water, Silver nitrate and Ammonia. Once this is done, you rinse the mirror with distilled water and then put on a protective coating to let the silver "dry" without clouding or spotting up, in which case you have to strip the mirror using ferric chloride and start again. The protective layer is kind of a secret sauce as im not able to find anything on it. This is an expensive and potentially dangerous process. The cheapest possible way to do this is by having background knowlege about chemicals and having a cheap high quality supplier (stay away from sigma-aldrich please...). The second cheapest would be the spray silvering kit from "angelgilding dot com" (not advertising, just the only thing i could find) They also have a short series on how this process is done here on youtube.

@@Sharpless2 Thank you very much. Appreciate it.

Hi Julius, it took me about a spoonful or less, using the squeeze bottle method it is pretty hard to run out of even one spoonful! Cheers.

Yes that is very true. Economically it doesn't make much sense because of the aluminizing process, but for bigger mirrors it can pay off. But it's also good fun!

Thanks! Definitely something to try one day!

I’m pretty sure that the mirrors’ shape is determined during grinding, and the lap takes on that shape when it is pressed into the mirror.

Both start off flat. As you grind down through the grits, the top disc naturally takes on a concave shape and the bottom becomes convex. It does this because at the ends of the grinding strokes the disc on top overhangs the disc on the bottom resulting in more pressure and therefore more grinding action in the centre of the top disc and conversely more grinding on the edge of the bottom disc.

www.telescopemirrorblanks.com/mirror_blanks.html :-) Prices are quite reasonable. Of course you can get a polished and metalized mirror from China for not much more than the cost of materials... so unless you think that you can make a better mirror (or a different one!) than the Chinese optical fabricators... but that's the tragedy of affluenza... everything is so easy, today. You just buy it from somebody for next to nothing.

Hi, the one I use is called Acculap, it's pretty much a synthetic sort of tar. Thanks

Very similar, In action yes

Hi, thanks for the interest! I think if you read stellafane.org/tm/atm/mirror-general/materials.html this may give you a direction. Cheers!

Hi, It is Acculap. Google search should show suppliers. Good luck!

Thanks for the suggestion.