The pin block is the part into which the steel tuning pins are inserted.
The stability and strength of the pin block is fundamentally important for the stability of the tuning. For the smaller models the pin block is made of 21 layers of beech wood glued together at extremely high pressure using phenolic glue. For the larger models the pin block is made from 7 layers of hard Maple glued with the grains opposing each other, again using phenolic glue at high pressure.
The pin block must fit perfectly into its housing, which is positioned below the front crosspiece of the iron frame. This is a very delicate operation carried out manually by expert technicians to ensure the utmost precision.