Action Ratio and Dip and Blow and Etc.

[Farrell]

Action Ratio and Dip and Blow and Etc.
  ----- Original Message ----- 

    > Is the wippen flange centers at a good height? Usually 2 1/2" below the
    > HCH.
    I'm trying to imagine what HCH could be - and am failing. What is HCH?



  Hammer Center Height.

  Wippen flange centers are 2.65 inches below the HCH.


  Other alignments to consider: Action spread, knuckle core to jack center.


  The first photo with the knuckle at 16 mm had the core lined up properly
  with the jack center.  (Are those lead weights in the felt?)

  Yes. I'm using some old junk hammers simply as a way to put some weight out on the end of the shank. Lead was added to reach my target SW.

  Is that the blow distance?

  Close. In that picture the blow would probably be more like two inches. Actual blow would have the shank a little higher.


  On the relocated knuckle the jack center is too far forwards of the knuckle core.
  Can you increase the spread? 

  Again, sounds scary. You know me - I never want to modify anything - didn't the original master put this action together? Do you really think you know more than the original masters who were 5rd generation master piano builders and had been working at the Knabe factory for 109 years?

  Okay, I feel better now.  ;-)

  Yes, the wip rail can be adjusted. I'll try that and see what happens.

  Where does the rep lever contact the upstop screw,

  Pretty much in the middle of the leather piece, I think. I see where you are going with that. If I increase the action spread, the end of the rep lever will tend to migrate out from under the upstop screw. Another thing to evaluate. I think there is some slop there, but I'll check it out.

  where does the jack contact the let off button. Is there room to move?

  LOTS of room to move. I don't have the let-off rail installed. It's one of those old funky designs that is very difficult to get a tool in there for adjustment. My thought was to modify the let-off buttons attachments and go with something more akin to a Yamaha. But I haven't looked at that in quite some time. I'll look again.


  With that height of a heel extension the magic line is out the window.

  Why? The original setup missed the magic line by a mile. This modified setup is dead-on the magic line. The capstan and wip heels move together in perfect unison - no observable horizontal movement relative to one another.


  More importantly in your experimentation, where does the jack end up?
  When all is said and done, the jack needs to be in close proximity to the
  knuckle at the end of the keystroke.

  Without let-off buttons installed, I haven't tried that. But isn't the position of the jack relative to the knuckle a function of the amount of aftertouch? Probably more to it? Yes?


  Another consideration to really confound matters: stack relocation.
  Since the hammers are not on, the stack could be located further back
  a few mm. Then the hammers might have to be installed at a shorter radius.
  I've corrected a few problems by moving the stack back on quite a few actions.
  This would cause an increase in dip and lower touchweight.


  Fun, ain't it?

  Ah, yeah, right. In fact it is. I only wish I had more time to kick back and really play with this thing - BUT I GOTTA GET IT DONE!!!!!!!!!

  Oh well.   ;-)

  Terry Farrell
-- 

  Regards,

  Jon Page
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20070704/2c7ece6e/attachment.html