Pianotech

James,

I don't work on many Bechstein's, but I have some recommendations based on extensive experience regulating a variety of different makes of pianos.

Second issue first: if hammers are missing left and right strings, I would back up and check every aspect of hammer assembly regulation (after tightening the hammer flange screws, of course): travel, square, and align hammers to strings (and, again, ensure that the flange screws are good and snug!). I have rebuilt the actions on Bosendorfers with those indexing pins in the notches at the proximal end of the hammer flanges. When those pins interfer with proper regulation, I have simply removed them (having run this by a Bosendorfer expert). It is worth mentioning that when doing this, I routinely add sandpaper on top of the hammer rail, under the flanges, so as the screws inevitably get a bit loose, at least we don't have two smooth surfaces facing each other that would allow the flanges to move sooner rather than later.

I will be interested to learn what those who make soundboards and know a lot more about them than I do have to say about soundboard movement due to loss of moisture. While I have no hard evidence, I do imagine that the let-off button cloth punchings also change in dimension with changes in the relative humidity, which also contributes to closer let-off in the dryer season. So, the soundboard is losing crown, making the strings lower, and if the let-off button punchings are becoming thinner, let-off would be even closer to the strings as well.

Hope that helps (and that at least some of what I have written is true!),

Alan

Thanks for the response very useful info since I know what to call those pins "indexing pins" . This piano has a very fascinating history built in 1877 in Berlin and first owned by a LT . Eventually it came to SC and was in a furnished plantation style house with many antiques. It was in rough shape until it was rebuilt in this area . The owner was generous to donate it to a local church and it has been used for many church services and concerts. 

I plan to place a data logger in it to get 24 x 7 temp, rh and dew point readings which result in some great graphs.  The piano is massive with ice cream cone turned legs and large cross beams . I am not sure how much felt shrinks in lower humidity but I know that periods of rain and high humidity can affect hammers 

I would like to trace the journey of this piano since it survived 2 world wars, ocean transport, relocation to England and then the US . There is a signature and date on the key holddown strip stating it was tuned in February 1946

James,

I don't work on many Bechstein's, but I have some recommendations based on extensive experience regulating a variety of different makes of pianos.

Second issue first: if hammers are missing left and right strings, I would back up and check every aspect of hammer assembly regulation (after tightening the hammer flange screws, of course): travel, square, and align hammers to strings (and, again, ensure that the flange screws are good and snug!). I have rebuilt the actions on Bosendorfers with those indexing pins in the notches at the proximal end of the hammer flanges. When those pins interfer with proper regulation, I have simply removed them (having run this by a Bosendorfer expert). It is worth mentioning that when doing this, I routinely add sandpaper on top of the hammer rail, under the flanges, so as the screws inevitably get a bit loose, at least we don't have two smooth surfaces facing each other that would allow the flanges to move sooner rather than later.

I will be interested to learn what those who make soundboards and know a lot more about them than I do have to say about soundboard movement due to loss of moisture. While I have no hard evidence, I do imagine that the let-off button cloth punchings also change in dimension with changes in the relative humidity, which also contributes to closer let-off in the dryer season. So, the soundboard is losing crown, making the strings lower, and if the let-off button punchings are becoming thinner, let-off would be even closer to the strings as well.

Hope that helps (and that at least some of what I have written is true!),

Alan

A Dampp-Chaser is unlikely to have any effect on the action or bridges, since it only affects the air right below the soundboard. I think that bridge expansion and contraction is more important in tuning instability and probably string height than the soundboard, though this is based on empirical evidence, not precise scientific experiment. 

Concerning centering hammers with those pins, It is actually quite possible, due to the fact that the hole in the flange is larger than the screw, and the slot in the flange is slightly wider than the pin. Simply loosen the screw and get the flange loose from the sandpaper under by prying a bit between the flange and its neighbor. In my experience, there has always been ample ability to shift the hammer to the desired alignment. 

While this design precludes using flange-spacing tools, it doesn't preclude refined spacing. You just have to do it outside the cavity. 

Original Message:
Sent: 12/19/2025 3:06:00 PM
From: Fred Sturm
Subject: RE: C Bechstein hammer blocking

A Dampp-Chaser is unlikely to have any effect on the action or bridges, since it only affects the air right below the soundboard. I think that bridge expansion and contraction is more important in tuning instability and probably string height than the soundboard, though this is based on empirical evidence, not precise scientific experiment. 

Concerning centering hammers with those pins, It is actually quite possible, due to the fact that the hole in the flange is larger than the screw, and the slot in the flange is slightly wider than the pin. Simply loosen the screw and get the flange loose from the sandpaper under by prying a bit between the flange and its neighbor. In my experience, there has always been ample ability to shift the hammer to the desired alignment. 

While this design precludes using flange-spacing tools, it doesn't preclude refined spacing. You just have to do it outside the cavity. 

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Fred Sturm
University of New Mexico
fssturm@gmail.com
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
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