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Half Felt BR Punching to Increase Action Resistence

  • 1.  Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 27 days ago
    I've never had occasion to use the BR punching to as a quick way to lower action resistance (presumably BW, because it acts on the leverage). So I don't know the precision (across the keyboard) in which it lowers BW: the variance in its effect. Also, not having the experience here, I wouldn't know if the closeness to the BR pin's hole will vary the degree to which trimming it will vary its effect ( ie., from 0 untrimmed to its full amount, actually trimming into the hole.

    All of this would be useful to know because I have an action in which the resistance (either friction or BW) needs to be raised. Because we won't know by how much until the pianist tries it, it has to be both variable and undoable. Also, temporary alterations in BW (binder clips on the shanks) or FW (back-leading on the keys) also increase the inertial resistance, and I'd like to avoid putting extra variables into the experiment. Turning the front key pins (to increase friction) is variable and undoable. However, I'd rule it out as a permanent fix.

    So, trimming the BR punchings seems to be the trick IF trimming on the backside is as reliable an adjustment as trimming the front side. I also would do any trimming on felt punchings of my own, swapped in to avoid make permanent changes on the existing ones.

    Additional info: the action is a new WNG, so a thorough repinning of the shanks would be a little trickier than if they were wood (the best idea here is pin pricks at 3/9o'clock around the birdseyes).

    Ideas? 10Q.

    ------------------------------
    William Ballard RPT
    WBPS
    Saxtons River VT
    802-869-9107

    "Our lives contain a thousand springs
    and dies if one be gone
    Strange that a harp of a thousand strings
    should keep in tune so long."
    ...........Dr. Watts, "The Continental Harmony,1774
    +++++++++++++++++++++
    ------------------------------


  • 2.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago

    To change the AR I prefer to shim the balance rail with a thin (1/8" strip) of thin veneer (see attachment).  Put it behind the BR pin to lower the action ratio and put it in front of the BR pin to raise the AR.  You may have to adjust the key level or the dip. 

     

    Note that a change to the AR will change inertia (as well as BW).  Since inertia is primarily a function of the AR and the hammer mass any change to the AR will change the inertia.

     

     

     






  • 3.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago
      |   view attached
    Hi Bill,

    Hammer  Strike weight or AR changes will give you the most bang for you buck.   The pianist will feel more change in playing quality from changing BW  a few grams by changing either or those than by changing BW a few grams by changing key lead Front Weights or Friction Weight levels.   Binder Clips for increasing Stike Weight are quick, make a big change, and are reversable.   The change may be made permenant by installing lead wire bits in the hammer moldings.  Gluing the cloth BR punching agianst the bottom of the ey with a releasable glue  (like Hide glue) then cutting up to even more than half - to the edge of the BR pin - will make a significant change in Inertia and is reversable with some work.  Usually, after cutting punchings the key leavel changes are insignificant.  Importantly, this option only works if the balance rail bevel does not undercut the punching stack.   I first used the method that David Love discribes, which takes a little more work, many years ago on an action I installed NY hammers on.  The client wanted a different sound so I replaced with lighter cold pressed Ronsen hammers.  He loved the sound but now the action was too light so I inserted strips of veneer across  and against the front of the BR pins.  They are sitll there after 20 or so years and still working fine.    Technicians who first come across this method often worry that it might create chucking keys after years of use but there is no evidence of this.  see attached photo of shims like Love's but on the proximal side.

    Also as to friction.  A couple of days ago I was working on a church piano I rebuilt in the early 1990s.  I had installed friction my friction adjust hex head screws in the hammer flanges.  The concert pianist who was rehearsing on the piano was very sensitive and prone to Grousing.  While I was prepping  the action I noticed that the friction in most of the hammer flanges had dropped to leass than 1gram.   I set a sample bass, midrange, and treble notes to 5grams rotational and tipped the action on its' side against the wall so that the shank on the sample notes fell back with a controlled motion.  I set the rest of the flange frictions so that they  all fell in a controlled motion per the sample.   Took about 20 minutes.    I didn't say anything to the pianist.  Her comment was that the action was more even and easier to control when playing pianissimo.   She didn't say it felt heavier.

    Happy Hunting Bill!

    PS - For those unfamiliar changing ratio and inertia by working the BR punchings may refer to PTJournal December 2014: http://www.stanwoodpiano.com/December2014.pdf




    ------------------------------
    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
    ------------------------------



  • 4.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago
    No, trimming the back side will have 0 effect on the resistance. The key is pressed down at the front, meaning it will pivot at the front side of the punching. Changing the back side will not affect the pivot point in any way. It may, however, make the key level regulation unstable and inconsistent.




  • 5.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago

    The key at rest actually sits on the backside of the BR punching and as it is depressed it rotates onto the front side of the punching. The key ratio, therefore, is actually changing through the key stroke. So cutting the backside of the punching will slightly move the pivot point forward and raise the key ratio and the AR somewhat. Cutting the punching on the front side only affects the KR after the key contact point pivots forward during the last half of the key stroke which is why it's not as effective as the shim method.

    We will feel the most change if what we do affects the AR at the beginning of the stroke rather than at the end because inertia is more of a factor when we are initiating movement. Therefore cutting the backside of the punching to raise the AR is more effective than cutting the front of the punching to lower the AR. 



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



  • 6.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago
    BTW here's another approach, available from Jahn.  Called "optimized balance washers" these allow you to modify the pivot point with several options.  You can also purchase a test kit.  No reason they can't be pivoted 180 degrees to allow for changing the action in either direction.  Similar to the Steinway bearings these establish a single pivot point which you don't get with a flat punching.



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



  • 7.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 11 days ago
    Boy it doesn't take much in this Forum to get a very interesting conversation going. It's nice to know that the half-punching works in both directions. Thanks, everyone!

    This is just a temporary mock-up. The binder clip on the hammer affects all three forces (friction, gravitational, and inertial) and is immediately reversible. The half-punching (in this case, to increase Strike Balance Ratio) works on the latter two, but to do this with the existing BR punchings is not reversible, leaving you with a new, different SBR, which is either lighter or heavier than the original. If you carefully remove the existing BR punchings and swap in a set of half-punchings, the swap-in set had better be the same thickness as the originals, the aftertouch change, complicating the pianist's impressions. The best of all worlds is that someone has already set the keyboard with half-punchings, and all you have to do is rotate them. Even here, though there's the chance that the key level will get upset and you'll have to spend some time, adding or pulling paper punchings to restore the level.

    So, I'm going with the binder clips. Now the how-to-question: will the clips damage WNG shanks? Any DAMHIKs out there?

    ------------------------------
    William Ballard RPT
    WBPS
    Saxtons River VT
    802-869-9107

    "Our lives contain a thousand springs
    and dies if one be gone
    Strange that a harp of a thousand strings
    should keep in tune so long."
    ...........Dr. Watts, "The Continental Harmony,1774
    +++++++++++++++++++++
    ------------------------------



  • 8.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 11 days ago
    Small binder clips won't work on WNG.  You might have a chance with mini binder clips.  You can put a small  over a mini.  If weight is to much choke the position back towards the center.

    ------------------------------
    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
    ------------------------------



  • 9.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 11 days ago
    From the WNG site: "Each shank in every Flex has an outer diameter of 4.67mm and a wall thickness of .80mm"

    At a 0.184" diameter,  the mini will grab nicely. For a small, a 7/32" drill bit (0.219") has a similar grip. Sorry, I'm doing this in the house, where all I have is the fractional series; the number and letter series are over at the shop. The # series size for 0.184" would be between 14 & 13. If I really needed the extra weight of the small, I could lay a shim of ~1/16" cardboard between the flat bottom of the clip and the shank to make the small work like a mini.

    What I was more concerned with was would the walls of the shank collapse under the squeeze of a binder clip. Given how close the mini is (and the small would be, thus shimmed), I'd guess this would not be a problem. But it never hurts to ask for a DAMHIK <G>.


    ------------------------------
    William Ballard RPT
    WBPS
    Saxtons River VT
    802-869-9107

    "Our lives contain a thousand springs
    and dies if one be gone
    Strange that a harp of a thousand strings
    should keep in tune so long."
    ...........Dr. Watts, "The Continental Harmony,1774
    +++++++++++++++++++++
    ------------------------------



  • 10.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago
    Bill
    Just an FYI, Jurgen at Piano Forte, does have very nice half cut balance punchings available. If you want a very nice consistent looking cut on each punching, this is the way to go.
    Both David Stanwood and David Love's advice are spot on.

    ------------------------------
    Tom Servinsky
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  • 11.  RE: Half Felt BR Punching to Increase Action Resistence

    Registered Piano Technician
    Posted 26 days ago
    Yes, however the effect would be slight by comparison as only a small bit of the punching is cut off.

    ------------------------------
    David Stanwood
    Stanwood Piano Innovations Inc.
    West Tisbury MA
    508-693-1583
    ------------------------------