[pianotech] Damper spring

[John Delacour]

At 09:05 -0400 19/06/2011, Richard Ucci wrote:

>Last week I was working on an old Chickering upright and wanted to 
>replace a bass damper spring.
>It was pinned and after removing the pin it still was connected. 
>Seems to also have cord in there as well.
>Why both? When redoing does it need to be same again?

The most common thing found is a pin with bushing cloth or thin 
facing cloth, not cord.  The pin is there because without it the 
pressure of the coil of the springs would push out the cloth.  The 
cloth is there to prevent wear and squeaking and the pin is there for 
stability.  If you use just cord you will probably find that it pulls 
up.  The pin and cloth allow for free movement of the coils.  If you 
use something that is a tight fit in the coils, the coils will be 
unable to do their job of closing up as the spring tightens and the 
life of the spring will be greatly reduced through fatigue.

Tear of some strips of cloth as though you were going to rebush 
centres, but the cloth can be thinner since it only needs to be tight 
enough to keep the pin in place, so it is an easier task than 
rebushing centres.

JD