Measuring sheet into semispheres

[TimothyK45363]

I’m sure there are books on the matter but I’m just curious if anyone has a quick answer for the diameter size change from a round piece of sheet dapped into a semi sphere. I’ll probably just end up doing a practice run and measuring the difference, but it would be nice to save myself some time and metal.

[GaryK]

Check out this discussion:
Forumula of disk size for dome making

[TimothyK45363]

Thank you So those are all the key words I needed to use when I was searching for the topic

[Brennan-AG]

I never would have known either. Good question

[AurumArcanum]

Forumula of disk size for dome making

Today I wanted to create a dome that would have an 8mm inside diameter and a 9mm outside diameter (.5mm sheet). I had absolutely no idea where to start to estimate the right size disk for starting - and hence I have two very sore spots on my fingers from so much sanding down! DOH! are there any formulas for this? or good rules of thumb even? I am mathematically challenged so if this is obvious I do apologize Thank you for any help! Lucy

Here’s the link to that topic for those who don’t want to search