Pianotech

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

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Karl Roeder
Pompano Beach FL
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Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
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Thanks Mr Gravagne,

The string heights are around 192mm. A little higher in the mid-range and down to 190 at note 88. The stack is already a little too high from the factory (1967) as evidenced  by a few notches from drop screws at the bottom of the cornice. The action comes out easy enough if you raise the middle three glide studs. With the original teflon era action parts, (16mm knuckle)the blow distance is between 49mm in the bass and 47mm in the top treble. At 48mm in the middle a 9mm touch depth gives 1mm aftertouch with 1mm letoff. I haven't run the numbers through AGP yet, but plan to tonight. I've just been thinking if I lower the stack by about wo millimeters. That I might be able to better accommodate a standard hammer bore distance and by using modern parts (17mm knuckle) get a more standard 10 mm touch.

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Hi Wim,

The cavity opening is immaterial providing it isn't too short for drop screw clearance. What matters is the dimension from the keybed to the string plane. On a D the dimension should be 7-5/8" (194 mm) at around note 62.

RE trouble fine regulating, can you explain exactly what the problem is?

Without seeing the piano,I have many questions beginning with what is the hammer bore dimension and how was it determined? Next, what is the dimension from the keybed to the hammer flange center pin (you have to do this on the bench)? In the photo of the Baldwin 9', this dimension is 148 mm.Note that one hammer flange assembly has been removed for visual access.

And lastly, for now, what is the dimension from the bench to the wippen center pin?

With enough scrutiny, there is always an answer.

ng

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Hi Wim,

The cavity opening is immaterial providing it isn't too short for drop screw clearance. What matters is the dimension from the keybed to the string plane. On a D the dimension should be 7-5/8" (194 mm) at around note 62.

RE trouble fine regulating, can you explain exactly what the problem is?

Without seeing the piano,I have many questions beginning with what is the hammer bore dimension and how was it determined? Next, what is the dimension from the keybed to the hammer flange center pin (you have to do this on the bench)? In the photo of the Baldwin 9', this dimension is 148 mm.Note that one hammer flange assembly has been removed for visual access.

And lastly, for now, what is the dimension from the bench to the wippen center pin?

With enough scrutiny, there is always an answer.

ng

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Warning; Long winded post.

Thanks all for the replies.

It took some digging but I finally found the factory specs for stack height.

The hammer flange center is at 148mm from the key bed and the rep flange center is at 85mm. So in the middle of the scale, where the string plane is highest in this piano, String height (193mm) less stack height(148mm) at the hammer flange center  tells me I want a bore distance of 45mm. Standard Steinway bore distance here is 46mm. The string height drops to 192mm at note 63 and to 190mm at note 88. So standard bore will be 1mm too long in the middle and 3mm to long at the top. This will have the hammers under centering at the contact with the strings perhaps acceptably in the mid-range but badly in the top sections.With a rep flange center of 85mm there is about the right amount of distance (193 - 85 =108) from the strings in the middle but 3mm too little in the top.

In the bass the strings are at 199mm height which with a 148mm stack height wants a 51mm hammer bore vs the standard Steinway bore of 54mm.

So here's where my thought process and innate sense of geometry becomes suspect for me. I'm thinking that I could lower the front of the stack by 2mm and get a better average distance from the strings and the hammer flange centers. That way I can order a set of hammers bored 1mm short of Steinway spec and still have an acceptable angle at hammer contact throughout. It would also address the problem of the drop screws hitting the pinblock. By leaving the back feet of the stack unchanged I can reduce the amount I need to lower the capstans and also reduce the change in backcheck hammer tail relationship (hat tip to Mr. Dierauf). 

Mr. Blees, Model D's of the era you mention frequently had string heights far higher than spec. I've seen some with 197mm (7 3/4") heights in the mid range. That can make setting touch depth a real problem even if you can raise the stack a bit.

Still haven't figured out the wood working involved. Open to your thoughts and suggestions.

Hi Wim,

The cavity opening is immaterial providing it isn't too short for drop screw clearance. What matters is the dimension from the keybed to the string plane. On a D the dimension should be 7-5/8" (194 mm) at around note 62.

RE trouble fine regulating, can you explain exactly what the problem is?

Without seeing the piano,I have many questions beginning with what is the hammer bore dimension and how was it determined? Next, what is the dimension from the keybed to the hammer flange center pin (you have to do this on the bench)? In the photo of the Baldwin 9', this dimension is 148 mm.Note that one hammer flange assembly has been removed for visual access.

And lastly, for now, what is the dimension from the bench to the wippen center pin?

With enough scrutiny, there is always an answer.

ng

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Warning; Long winded post.

Thanks all for the replies.

It took some digging but I finally found the factory specs for stack height.

The hammer flange center is at 148mm from the key bed and the rep flange center is at 85mm. So in the middle of the scale, where the string plane is highest in this piano, String height (193mm) less stack height(148mm) at the hammer flange center  tells me I want a bore distance of 45mm. Standard Steinway bore distance here is 46mm. The string height drops to 192mm at note 63 and to 190mm at note 88. So standard bore will be 1mm too long in the middle and 3mm to long at the top. This will have the hammers under centering at the contact with the strings perhaps acceptably in the mid-range but badly in the top sections.With a rep flange center of 85mm there is about the right amount of distance (193 - 85 =108) from the strings in the middle but 3mm too little in the top.

In the bass the strings are at 199mm height which with a 148mm stack height wants a 51mm hammer bore vs the standard Steinway bore of 54mm.

So here's where my thought process and innate sense of geometry becomes suspect for me. I'm thinking that I could lower the front of the stack by 2mm and get a better average distance from the strings and the hammer flange centers. That way I can order a set of hammers bored 1mm short of Steinway spec and still have an acceptable angle at hammer contact throughout. It would also address the problem of the drop screws hitting the pinblock. By leaving the back feet of the stack unchanged I can reduce the amount I need to lower the capstans and also reduce the change in backcheck hammer tail relationship (hat tip to Mr. Dierauf). 

Mr. Blees, Model D's of the era you mention frequently had string heights far higher than spec. I've seen some with 197mm (7 3/4") heights in the mid range. That can make setting touch depth a real problem even if you can raise the stack a bit.

Still haven't figured out the wood working involved. Open to your thoughts and suggestions.

Hi Wim,

The cavity opening is immaterial providing it isn't too short for drop screw clearance. What matters is the dimension from the keybed to the string plane. On a D the dimension should be 7-5/8" (194 mm) at around note 62.

RE trouble fine regulating, can you explain exactly what the problem is?

Without seeing the piano,I have many questions beginning with what is the hammer bore dimension and how was it determined? Next, what is the dimension from the keybed to the hammer flange center pin (you have to do this on the bench)? In the photo of the Baldwin 9', this dimension is 148 mm.Note that one hammer flange assembly has been removed for visual access.

And lastly, for now, what is the dimension from the bench to the wippen center pin?

With enough scrutiny, there is always an answer.

ng

Does anyone here have strong feelings about the relationship between action stack height and string height in Steinway pianos? I seem to remember sometime ago there was a preference for the repetition center pin to be 4 1/2 inches below the strings I think this might have come from Dietz on Steinway regulation but it's been a long time and I can't be sure. i'm working on a model B action where the hammer shank center is about 3/32 inch higher than I would like and the repetition center is only 4 1/4 inches below the strings. In the current set up that would mean that I need a highly customized  bore distance for the new hammers. I'm replacing all the action parts and I'm considering lowering the action stack but I'm not exactly sure how I'm going to thin the walnut support pieces. Just thought I'd throw this out there and see if I could entice the people who are smarter than me to weigh in.

------------------------------
Karl Roeder
Pompano Beach FL
------------------------------