On the keyboard end of the piano, the strings begin at the tuning pins. The tuning pins, also called wrest pins, are steel cylinders that are used to bring the piano strings into proper tune. The string goes through a hole in the pin, and then wraps tightly around the pin in three or four coils. The top of the tuning pin is squared off so that the piano technician can easily turn the pin with the tuning hammer. The bottom half of the pin is serrated, to ensure that the pin tightly grips the pinblock. The pinblock, also called the wrest plank, is a wooden plank that stretches the full eyboard width of the piano. The tuning pins are driven into holes in the pinblock, which must grip the pins and keep them from turning. 
The pinblock is made of several layers of wood that are laminated (or glued) together. The layers are made of hardwood, usually beech or maple, and each layer alternates the direction of the grain in order to strengthen the pinblock. The pinblock is about one and a half inches thick, and the number of laminations varies from as little as three to as many as twenty-four layers.
After the string leaves the tuning pin, it passes over the front duplex bridge, a small bridge cast into the cast-iron frame which pushes the path of
the string slightly upward. The string then goes through the agraffe, or under the capo d'astro. The treble strings pass under the capo d'astro, a metal bar cast into the frame, which pushes down on the string and defines one end of its speaking length. The tenor and bass strings pass through an agraffe, a metal guide screw that spaces the strings and also defines their speaking length. The portion of the string that stretches between the front duplex bridge and the agraffes (or capo d'astro) is not struck by the hammer, but is designed to vibrate sympathetically with the main speaking length of the string, this is called duplex scaling.
The speaking length of the string is defined on the far end of the piano by a wooden bridge that is glued to the soundboard. The string is guided across the bridge by bridge pins, and then ends beyond the bridge at the hitch pins, metal pins that are driven into the far end of the cast-iron frame. Parts of the strings that are outside of the speaking length and not intended to vibrate are damped by pieces of felt.
The pinblock is made of several layers of wood that are laminated (or glued) together. The layers are made of hardwood, usually beech or maple, and each layer alternates the direction of the grain in order to strengthen the pinblock. The pinblock is about one and a half inches thick, and the number of laminations varies from as little as three to as many as twenty-four layers.After the string leaves the tuning pin, it passes over the front duplex bridge, a small bridge cast into the cast-iron frame which pushes the path of
the string slightly upward. The string then goes through the agraffe, or under the capo d'astro. The treble strings pass under the capo d'astro, a metal bar cast into the frame, which pushes down on the string and defines one end of its speaking length. The tenor and bass strings pass through an agraffe, a metal guide screw that spaces the strings and also defines their speaking length. The portion of the string that stretches between the front duplex bridge and the agraffes (or capo d'astro) is not struck by the hammer, but is designed to vibrate sympathetically with the main speaking length of the string, this is called duplex scaling.
The speaking length of the string is defined on the far end of the piano by a wooden bridge that is glued to the soundboard. The string is guided across the bridge by bridge pins, and then ends beyond the bridge at the hitch pins, metal pins that are driven into the far end of the cast-iron frame. Parts of the strings that are outside of the speaking length and not intended to vibrate are damped by pieces of felt.
