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hammer rail to wippen spread

  • 1.  hammer rail to wippen spread

    Member
    Posted 09-28-2018 20:47
    What is the magic number for checking if there is growing action brackets?
    113 mm center pin to center pin seems right but so does 115 mm

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    Keith Roberts
    owner
    Hathaway Pines CA
    209-728-2163
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  • 2.  RE: hammer rail to wippen spread

    Registered Piano Technician
    Posted 09-28-2018 21:16
    Keith

    The 113 MM number is in the ball park.  I was working for a store carrying Young Chang products (I am presuming this is the brand in question here) when this became a well known malady.  We even kept a stock of action brackets as we were doing at least one per month and became quite proficient at the process.  

    Anything over 114 is clearly suspect.  If you are lucky no one has tried to regulate the action in the mean time so your repair will be simplified.  

    I have a bracket from that period in the shop and will try to capture a picture this weekend for you all.  It will show a "normal bracket" against one that has expanded.  The expanded one is now warped with an arch on the feet so it no longer sits flat on the bench, cracks, expanded out more that 1/4" and even has a "goiter" where the metal has expanded near the center.  Clearly a problem.  

    Best to you one the project.

    Mike Reiter

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    Michael Reiter
    Eugene OR
    541-515-6499
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    Original Message


  • 3.  RE: hammer rail to wippen spread

    Posted 09-28-2018 22:46
    115 is off the deep end. There will be no room in the rep window for the jack to traverse aftertouch, without jamming into the jack stop felt.

    Also, and this is a biggy...at anything over 113, most likely, the angle that the jack and jack center attacks the knuckle, will be such that the initial key movement, ie the first fractions of a second of the keystroke, will exhibit a much higher DW that the entire rest of the keystroke...sometimes up to 30g higher...just for the first milliseconds. This is a pianistically uncontrollable event...like trying to run on ice. It feels awful. Much of action frame design is worked out to avoid ever hitting this dysfunctional angular relationship. 

    I teach a class on this geometric relationship, and what spread and shank/whip center height differential is supposed to accomplish in an action frame setup. I will be teaching it next year at the national convention in Phoenix.

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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    Original Message


  • 4.  RE: hammer rail to wippen spread

    Posted 09-29-2018 00:04
    I think the specs are 112.5mm pre 1991, 113.5 post '91.

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    Regards,

    Jon Page
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    Original Message


  • 5.  RE: hammer rail to wippen spread

    Registered Piano Technician
    Posted 09-29-2018 11:30
    Just to be clear, Jim, the national convention will be in Tucson, not Phoenix.

    Bob Anderson, RPT
    Tucson, AZ


    Original Message


  • 6.  RE: hammer rail to wippen spread

    Member
    Posted 09-29-2018 14:51
    Tucson for the national. 

    Thanks Jim, I will be there most likely. 
    I have been a mechanic since I was 12 and then I went to UCSB as an engineer. Only had 2 quarters of ME. Vector analysis.  Geometry was probably my best  subject. 
    How do you measure action ratio? I measure along the bottom of the key because the thickness of the key is arbitrary. I can stand a dowels of equal weight and different height on the ends and change the numbers of action ratio when measured to the top of the key,, but the action ratio measured by weight will stay the same. 




    Original Message


  • 7.  RE: hammer rail to wippen spread

    Member
    Posted 09-29-2018 15:10
    No it's not a YC. Some action brackets from different eras of pot metal had growing pains. Formulas changed based on what was available. Contaminated scrap metal would be another problem. 
    I'm looking at a rebuild that might have too much space between the drop screw pad and the hammer rail. 
    I have found wippen rails that are warped and shims that have been messed with

    It's a Steinert 1906. Someone did a quick hammer job that flattened the knuckles and added a ton of lead but didn't do the key bushings or key frame in maybe as recent as 1980



    Original Message


  • 8.  RE: hammer rail to wippen spread

    Registered Piano Technician
    Posted 09-29-2018 02:59
    Sorry misread the question my previous answer makes no sense.


  • 9.  RE: hammer rail to wippen spread

    Registered Piano Technician
    Posted 09-29-2018 10:34
    Sorry misread that this was about determining expanding action brackets.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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    Original Message


  • 10.  RE: hammer rail to wippen spread

    Posted 09-29-2018 06:30
    Jon posted the correct numbers. I just did a replacement job last week. Put a good light on the brackets and look closely - I have found that you'll almost always be able to see cracks in the brackets. Sometimes you have to look real close - it's the kind of thing that you might not see them at first at all - and then once you see one crack, you'll see dozens of them. I took a few pictures last week comparing new (greenish) to old (grey). And yeah, unfortunately, on this job, previous techs had tried to regulate to correct for the growing brackets. I also did a bracket job maybe six months ago and it was fortunate that no one had tried to correct for the blocking hammers - I put new brackets on and presto: the regulation was that of an unregulated 30 year old piano (I guess that's good.....).

    Enjoy! I like doing these jobs.

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    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
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    Original Message


  • 11.  RE: hammer rail to wippen spread

    Posted 09-29-2018 12:28

    <Analyze the product of all three levers first and then ask if a modification is required based on the overall action ratio. Only then does the meaning of "the spread" have real relevance.

    The stack action center locations are functionally and practically about jack functionality. Spread's effect on leverage is for all intent and purposes un-measurable.

     It is correct that there are 3 levers to be considered in overall action ratio. However, the parts of the whip lever that spread is involved in, must allow the jack to function adequately. This is non-negotiable...the stack must accommodate the inherent geometry imposed by manufactured whippen, ie, the geometry which allows it to create letoff. As such, in a practical discussion such as this, this lever, the portion of the whip lever that involves spread, can be considered to be a constant.   

    Said another way, the stack design must adhere to the whip's manufactured design, setting up the conditions where it is possible for the jack, geometrically, to create letoff. That is step one. Step two, after having set up the conditions where it is functionally possible for letoff to occur, one must set up key, shank and lower whip levers(heel), to achieve letoff and aftertouch in the span of a full dip. 

    To repeat, as this is a common misunderstanding, spread's effect on leverage is for all intent and purposes practically un-measurable. If there is a leverage issue to be addressed, work outside the functional parameters of the stack to effect these changes. Spread's job is simply to set up the geometry so the jack is functionally capable of achieving letoff.

    ....right...Tucson...my bad...



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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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    Original Message


  • 12.  RE: hammer rail to wippen spread

    Posted 09-29-2018 13:44
    When setting up the overall top action positioning, I use three parameters.
    Hammer Center Height equals String Height minus Hammer Bore, taking into account pitch angle for the hammer to hit perpendicularly.
    Wippen Center Height is 64 mm below Hammer Center Height.
    The spread is adjusted so that the core of the knuckle is aligned to the jack center at rest.

    This usually produces the best outcome for adequate After Touch. Sometimes the Top Action needs to be relocated for the best Strike Point.

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    Regards,

    Jon Page
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    Original Message