> It's interesting to see how manual the process still is.
This reminded me of a programme I saw a couple of years ago about making a perfect sphere. From what I can remember they said that was hand finished. I've just done a quick search and it looks like it would have been Achim Leistner making the 1Kg sphere.
Narration: The sphere started life as an ingot of pure silicon 28, brought here from Germany. Silicon crystal was chosen as the material because of its uniform atomic structure. The silicon ingot is cut and ground into a rough ball shape. Then Achim starts the painstaking process of transforming it into a near perfect sphere.
Achim Leistner: And this can only be done by hand because you actually have to feel what is happening. When you’re taking off a nanometre or 5 nanometres, or 10 nanometres or 20 nanometres, some of the errors we’re trying to correct are in the vicinity of only a few nanometres.
Narration: That’s a few billionths of a metre! If this sphere was the size of the earth, that accuracy would be equivalent to changes in height of only 4 or 5 metres over the entire surface of the planet. But that’s only half the challenge. To redefine the weight standard as a universal constant, the team also have to count the number of atoms in the sphere.
This reminded me of a programme I saw a couple of years ago about making a perfect sphere. From what I can remember they said that was hand finished. I've just done a quick search and it looks like it would have been Achim Leistner making the 1Kg sphere.
From http://www.abc.net.au/catalyst/stories/s2038283.htm and more info at https://www.newscientist.com/article/dn14229-roundest-object...
Narration: The sphere started life as an ingot of pure silicon 28, brought here from Germany. Silicon crystal was chosen as the material because of its uniform atomic structure. The silicon ingot is cut and ground into a rough ball shape. Then Achim starts the painstaking process of transforming it into a near perfect sphere.
Achim Leistner: And this can only be done by hand because you actually have to feel what is happening. When you’re taking off a nanometre or 5 nanometres, or 10 nanometres or 20 nanometres, some of the errors we’re trying to correct are in the vicinity of only a few nanometres.
Narration: That’s a few billionths of a metre! If this sphere was the size of the earth, that accuracy would be equivalent to changes in height of only 4 or 5 metres over the entire surface of the planet. But that’s only half the challenge. To redefine the weight standard as a universal constant, the team also have to count the number of atoms in the sphere.