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Determining Upright Hammer length

  • 1.  Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-23-2017 08:36
    I am installing a new action in an upright piano and I'm wondering if there is a procedure for determining the length of the hammers.  I've kept samples of the originals which I can duplicate, but I don't always trust what's there.  I also slightly changed the action position.  I mostly restore grands so I'm a little rusty with uprights.  
    Bill

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    William McKaig
    Tampa FL
    813-831-4179
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  • 2.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-23-2017 09:02
    Bill, 

    New butts and whippens or complete (as in WNG) action?

    It seems to me that if you make a mock up with the same rake angle and all, you can check first to see if the original hammer bore comes out with 1.75" strike distance. If not, make adjustments from there. Take angle is very often in the 5° range...Steinways about 7° or so.

    I'm sure others will be able to be more scientific about it.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 3.  RE: Determining Upright Hammer length

    Posted 04-27-2017 01:46
    From my training in Germany I remember the following: Upright hammer bore length needs to be such that they "undercenter", i.e. the bore length needs to be 5 mm longer than the distance from the center pin to the string plane. The rule of thumb was that when the hammer is pushed against the string, the hammer shank is offset from vertical to the tune of approximately the thickness of a hammer shank.

    This helps to ensure that the hammer falls back nicely in a soft blow.

    I am not so sure if the hammer rake angle has much to do with this. I have seen many very high quality verticals, both old and new, whose hammers were not at 90 degrees when they strike the string. They all pointed downward. In other words, the rake angle is greater than needed to offset the shank angle. I could never quite figure that out, but this is what I have observed time and again.

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    Jurgen Goering
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  • 4.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-27-2017 07:42
    Jurgen, 

    I too have long been puzzled about the vertical setup vs the grand setup. Someone must know this stuff...

    Del? 😎



    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 5.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-27-2017 20:41
    Almost nobody is willing to go out on a limb with this issue. The action makers in China give the equivalent of a blank stare when asked. Much like the blank stare I received when dealing with a German action makers many years back while setting up the parameters of the actions in our pianos. 

    Jurgen's explanation is, I think, about as good as it gets. It explains why so many hammers are bored at a negative rake angle -- they come closer to striking the strings at a perpendicular angle. Otherwise there is no point to it. (Which is not to say that I have not seen vertical actions set up with the hammerbutt action center in the same plane as the hammer bore distance that still used -- god knows why -- a negative rake angle on hammer bore.)

    ddf

    --
    Delwin D Fandrich
    Piano Design & Manufacturing Consultant
    6939 Foothill Court SW, Olympia, Washington 98512 USA
    Email  ddfandrich@gmail.com
    Tel  360 515 0119  --  Cell  360 388 6525





  • 6.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-28-2017 01:49
    In grand piano design, is the flex of the shank taken into consideration? How much of a factor would this be on upright pianos where gravity does not contribute as much? But there must be some bending of the shank just the same as velocity at the action center would precede that of the hammer mass at the end of that lever. This might explain why the hammers would appear to be pointed downward when in contact with the string if only put there by technical observation and not actual playing, which could not be observed except by slow motion video.

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    Dave Conte
    Owner
    Fort Worth TX
    817-581-7321
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  • 7.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-28-2017 02:58
    OK. But I'm not sure just how many action makers had access to high-speed video in 1920. Or, for that, just how many action makers thought about hammershank flex at that time. 

    ddf

    --
    Delwin D Fandrich
    Piano Design & Manufacturing Consultant
    6939 Foothill Court SW, Olympia, Washington 98512 USA
    Email  ddfandrich@gmail.com
    Tel  360 515 0119  --  Cell  360 388 6525





  • 8.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-28-2017 08:06
    Jurgen,  I actually found a comment from you on an old post from Piano World where you stated the same criteria and that is what I used.

    What I find difficult about uprights is that there are no fixed points to go by....  There is no set distance for the action form the strings and the hammer rail can be moved around as well.  This leaves a lot of variables.  I normally match the original layout, but because I made a number of modifications to the action, I didn't completely trust the original numbers (I eliminated the brass rail set up and repositioned the action to accommodate the taller damper heads).  In the end I used Jurgen's suggestion along with using a bore length between 2 3/8"-2 1/2" (which is the range of standard bore available from the supply houses) and using samples to come up with the best layout.  

    The action is now installed and ready for regulation so we shall see how it comes out.
    Bill

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    William McKaig
    Tampa FL
    813-831-4179
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  • 9.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-28-2017 08:40
    Having installed one WNG complete vertical action, and been on the phone with Kawai about hammer bobbling issues, I learned that the action position (the stack if you will) is NOT etched in stone as both Jurgen and Del have essentially verified. Perhaps the height is, but the in and out position is not. Basically you move it around until it works.

    Bill, you are to be applauded for your bravery!

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 10.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-30-2017 18:50
    I'll add to Peter's comments that a small movement of the bottom of the action bracket toward or away from the string plane can make an enormous difference. I believe that once upon a time, a little more than 100 years ago, there were people who actually knew how this worked. However, they don't seem to have written any of that down. Makers today simply use templates and patterns.

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    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    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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  • 11.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 04-30-2017 21:55
    I think Fred is on the right track. The few vertical actions I have worked on to significantly optimize touch and tone have involved dealing with the center of gravity of the parts. Especially the hammer.

    If you place the bottom of the action as close to the string plane as the damper and pedal function will allow, the control is to look at how the proposed rest point of the hammer shank places the jack contact point. The jack must be able to get back under the butt and be able to be regulated with no lost motion. There is a point with an upright where the butt/jack relationship will begin to impinge the free return of the jack to rest and be able to have no lost motion between the whip and butt if the bottom of the action is too close to the string plane.

    Placing the bottom of the action as close to the string plane will create the most advantageous CG in the hammer butt assembly. Many of the actions I have inspected have been placed by the factory further away from the string plane than is possible. Combine this with the heavier hammers common now and no wonder so many verticals have bobbling hammers when played softly above the overstrung section. The CG is so bad the hammers are falling into the strings.

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    Edward McMorrow
    Edmonds WA
    425-299-3431
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  • 12.  RE: Determining Upright Hammer length

    Posted 04-30-2017 22:43

    Why do techs today think past pianomakers didn't share their knowledge??
    Way back in 1888, Hansing wrote a book. A book about every facet of piano design. Hansing  was very influential to other makers.
    Piano actions is chapter 12.  Even talks about cg in upright actions. 4mm offset etc etc.  You'd be surprised how much was figured out in 1888.
    Free Google book too.






  • 13.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 05-01-2017 08:35
    Chris,

    Sounds interesting. What is the name of the book?

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 14.  RE: Determining Upright Hammer length

    Posted 05-01-2017 08:45

    It's called "The Pianoforte it acoustic properties"






  • 15.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 05-01-2017 11:10
    Few of the 19th century piano builders understood inertia well enough to articulate specific design specs for that. They surely knew the geometric and CG issues perfectly well. And most knew that hammers must be shaped to reduce weight to get best results, but they always wanted to avoid the cost.

    Hansing's placement of a counterweight on the opposite side from the grand hammer to avoid key leads is an example of not understanding the tonal and touch consequences of hammer inertia.

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    Edward McMorrow
    Edmonds WA
    425-299-3431
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  • 16.  RE: Determining Upright Hammer length

    Registered Piano Technician
    Posted 05-08-2017 12:43
    Just wanted to give an update to the upright project.  I finished up the piano last week and the customer came an gave her seal of approval.  
    As to the hammer boring, I ended up adding about 1 1/2 mm to the original length and that seemed to work out well.  Adjustments between the hammer rail and key dip/after touch got the piano playing very well (better than I can play).  I used Abel natural hammers and Towkia parts including new stickers.  
    Bill

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    William McKaig
    Tampa FL
    813-831-4179
    ------------------------------