Another procedure that requires work by hand - watching this will give you a better idea of what voicing a piano is about, whether it's a Bechstein, Steinway, Yamaha or any other piano.
Here's the most intricate process of piano technology - the regulation of the action. Note the weights used to "measure" how much pressure is used to depress the key, the adjustments made to reduce or increase resistance of the key, the flame used to bend the hammer shank so the hammer hits the strings properly. This is a very good "overview" of a job that can take up to two to six days to complete!
They don't leave out any details here - while this is more promotional than informational, it's short, and interesting to note that the piano is upside down when the pedals are installed.
Keyboards are customized to fit each and every individual piano - in other words, you can't take the action out of one piano and drop it in another. Notice that it is all fitted by hand!
Notes From the Piano Bench
Questions and Answers and updated factoids concerning pianos in the 21st Century.