Working as your piano tuner Wilmington DE, Kenneth Keith Piano Services, I frequently see pianos that have one or more piano hammers that strike twice when the key is played only once. The explanation can be useful for all piano owners, because this situation is often mistaken by the pianist as evidence that the piano needs tuning. In our two previous blog articles, I explained a lot of the background information about double-striking or “bobbling” piano hammers, and I explained the two most common causes, “lost motion,” and improper hammer blow distance. This post is a continuation detailing the third of the four most common causes.

One way of explaining double hitting or “bobbling” piano hammers, is that the escapement action of the piano did not complete. On a vertical piano, the piano action is designed so that the mechanism that propels the hammer toward the string escapes when the hammer is 1/8″ from the string. The hammer then continues to the piano string of its own momentum, then rebounds away from the string so that the string is struck only once, and allowing the string to vibrate freely. If the action does not complete, then the mechanism does not escape completely. When the mechanism is still in an uncompleted position, the hammer structure will strike it  a second time and rebound toward the string, causing a second strike of the string.

There are four possible causes for the piano action to fail to complete. We have discussed the two most common causes in previous posts. The next cause is insufficient travel of the keys. If the piano keys do not travel the correct distance, the there is not enough travel among the action parts for the mechanism to complete and escape properly. One of the ten major adjustments to a piano action is the key height. The keys sit on two pieces of felt that get compressed with age and with use of the piano. This compression results in a slight lowering of the height of the piano keys, so that over time they do not have the same amount of movement as they had when the piano was new.

In our next post, we will discuss two ways to correct this problem. If you have any questions about your piano, please let us know. As your expert piano tuning Wilmington DE piano technician, we are always happy to help. Besides piano tuning Delaware, we proudly provide piano maintenance and piano services in Eastern Shore MD, Philadelphia and the Southern New Jersey areas.