09/09/2026
Last weekend was all about repinning hammers. I recently attempted to regulate a client's Hamilton upright, only to find that when the action was properly regulated the hammers would bobble, which is when the hammer strikes twice when the key is pressed only once. It turned out that the hammer friction was far too low, with each hammer fl**ge only needing about 2 grams of force to move, making them too bouncy due to lack of stiffness in the pivot point.
A second client has a Steinway Model O, a fantastic grand piano that has seen much wear and tear through the decades, and it also had hammer friction issues. Same deal here: regulation alone would not fix the playability problem, this time because the friction was much too high; about 8-10 grams of force needed to be applied to move the hammer fl**ge, which is extraordinarily stiff!
I keep 10 different sizes of centerpins, which are the main pivot points in each action part. By reaming and burnishing the cloth bushing around the pins, and adjusting the sizes of pins, I can make the hammers sit at any friction level I choose. By bringing the upright hammers into the 4-6 range and the grand hammers into the 2-4 range, both actions now play smoothly and can be regulated properly! If you're curious, I set the upright hammers to a higher level on the gram gauge because it has very new and stiff springs that pull the hammers back into place. I wanted stiffer centerpins to make sure that the hammers didn't bounce because of the high tension from the springs. Grand hammers just reset with gravity, so I like having those set a bit lower.