Hammers Bobbling 2024-08

On older pianos, we often hear and see the hammers bouncing on the strings like little bobbleheads. Here are a few causes and fix on an old Baldwin grand piano. Each piano may take different approaches of problem solving. 

The friction between hammer tail and backchecks is very low. The backcheck leather is worn and very smooth. A rough sand paper on a block is used to rough off the leather to increase friction. If the leather is completely torn, replacement will be needed.

The hammer tails has been polished by the backcheck leather through the years. The orange color has been transferred from the leather to the hammers tails. Use a rough sand paper on a block to sand off some of the leather mark,  as well as roughing off the wood to increase friction. Be careful not to take off too much wood. That will affect the regulation.

If the rep-springs are stronger than needed, the hammers may not check properly either. On this Baldwin, a screw can be turned to adjust spring tension. During tuning process, we can observe the spring tension by looking at how quickly and forcefully the hammers leave the backchecks. Mark the strong ones and the weak ones. Adjust them all after tuning. Most of the rep-springs on this piano are very strong. The hammers kick back with quite a force. They are all weakened by turning up the adjustment screws.

Clean all marks thoroughly. Check if all hammers are checking properly. Return action to the piano, play the notes up and down several times to see if any checking problems remain. Adjust accordingly.