Tuning pins, agraffes and hitch pins
(Photograph taken of a modern Wendl & Lung upright piano)


 

Wrest pins (tuning pins) in upright and grand pianos
Wrest pins (literally "holding pins") hold the string
at the correct tension and using a tuning lever they
can be tightened (clockwise) or loosened (anticlockwise).
This is called piano tuning. The skill of doing this involves
not just getting the string at the right pitch but also "setting"
the pin so that the wire doesn't change tension or the pin
move, causing the piano to quiclky go out of tune.

    

Agraffes in upright or grand pianos.
Higher quality older pianos and many modern pianos
have agraffes, especially in the bass. These are individual
bridges for the wires to pass through and need to be precisely
made so that the speaking section passes over a "clean" bridge.


   

Hitch pins in upright or grand pianos
These hold the strings at the bottom end. Normally
the same wire passes round the pin, which is convenient
as if the wire breaks, the same string can be slackened
at the tuning pin and wound round further on. This means that
a new string does not have to be fitted, obviating the need to
keep re-tuning the new string. However many makes
of piano choose to have single strings on every hitch pin, which
is less convenient as the new string may not match so well and
will ideally need to be blocked off at first as it goes out of tune quickly.