Hi Henry: In your post this morning you mentioned the "problem" of the hammers bobbling or not checking on a very soft blow. You specifically said that it did not bobble enough to strike the string a second time. The answer which Niimi and Edwards gave you is correct. Here's an example you can try. Push a key down so slowly that the hammer does not touch the string, pash through let-off very slowly. If you have repetition spring tension at all, the hammer will not drop down to check on the backcheck. Sometimes beginners think that this is a "failure" in not checking. However, it is showing the proper function of the repetition lever and its spring. With the slightest release of the key pressure, the jack will return under the knuckle and the key is ready for a repeat blow. Now, with just a little stronger key blow, the hammer will check. What bothers most people is that when they are checking for soft blow conditions at the end of regulation, a few hammers will check and some will not. This is due to two things primarily. 1. They may be varying their test touch slightly, or 2. there may be a very slight difference in the spring tension. Of course two other things can have an effect here and that is the key aftertouch unevenness and the non-precision let-off. Well OK, there is another thing and that is the unevenness of the bushing tightness or freedom from excessive friction, ie key bushings and flange bushings variation. Jim Coleman, Sr.
This PTG archive page provided courtesy of Moy Piano Service, LLC