For increasing tuning stability
When pins are loose in the pinblock, it can lead to unstable tunings, especially when accompanied by unstable humidity shifts. Most of the time, a process called pin pounding can lead to more stable tunings. With the pinblock securely braced, pins are driven further into the pinblock by hitting them with a hammer. This can add several torque pounds of force needed to move the pins, helping to keep the pins tight and reducing tuning degradation.