Steinway « O » New York 1910 (to be restored)
Pretty close.
Marking string height with a sharp pencil on a straight piece of wood.
The tape helps to record the distance between flange's center pin and keybed.
String distance from keybed, minus joint center pin distance from keybed produces drilling spot on new hammer.
Same as previous.
Hammers bored at the right spot, angle and pitch.
While the knuckles are moved away from the center pin, the jack must follow accordingly, hence a .045 balance rail punching will compress close to .035 inch just below 1 mm.
Tapering the hammers to remove weight.