I would regulate the blow distance, letoff/drop to specs. Then check that the hammers are checking properly, i.e. the backcheck not to close to the hammer tail. When hammer is moved through letoff/drop the top of the backcheck should be just a little bit below the hammer tail. Since you are not going to do any big repairs such as lower backchecks, if that was the problem, I'd make the hammer blow a little closer that spec to solve the problem. You don't want the hammer touching the backcheck at rest. David Ilvedson, RPT Pacifica, CA 94044 ----- Original message ---------------------------------------- From: "Mark & Janine Davis" <pianofortetechnology at saol.com> To: pianotech at ptg.org Received: 4/19/2010 11:29:36 AM Subject: [pianotech] Hammerheads resting on Backchecks when hammer is at rest >Greetings List > >I am needing to regulate an old C. Bechstein grand which has had some work >done on it in the not so distant past. The grand is about 100 years old. >What I plan to do is 1. Lubricate, 2. Align, 3. Regulate/Adjust wherever >necessary as best as possible. > >One thing I am not sure of is the hammerheads are resting against the >backchecks when at rest, even to the point that if you push the backcheck >away from the hammer, the hammer drops back down onto the rebound cushion. >I am aware that the hammerblow needs to be set and that by doing this the >shanks will be held up and off the rebound cushion and that the capstans >will need to be adjusted in order for this to take place. > >The little experimenting that I have done is to check if the hammer still >rests against the backcheck even when the capstan is adjusted so the hammer >is being held up and off the rebound cushion by the wippen/repetition >lever/jack and not by the backcheck, but the hammer is still resting against >the backcheck. This problem is in the middle and bass sections of the >piano, the treble does not seem to have this problem. > >The piano action with the keys and keyframe were removed from the piano and >brought to me after the keys were rebushed. I do not know what the >situation will be once the hammerblow is worked out and adjusted for at the >piano. I do not think that it will be different? > >Are the hammers resting against the backchecks a problem? And if so, how do >I sort it out? >Your advise will be much appreciated!!! > >Thank you, >Best regards, >Mark Davis >
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