Hammer assist spring ?

Stéphane Collin collin.s@skynet.be
Sat, 7 Jun 2003 16:49:46 +0200


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Hello Ric.

I got this pic from John Delacour.
I have much experimented with this action, as it was used in pre-1880 =
Bechstein pianos.
Walter Pfeiffer refers to it as a Herrburger-Schwander inverted-center =
hanging jack linked action (patent about 1850).
Indeed, there is lead at the back of the key.
Unfortunately, if the springs are very tight, they cause a very =
noticeable and objectionnable increase in extra force needed at set-off =
time, which can be ennoying at PP blows.
I consider those springs just perfect for evening out weight feel at the =
key, and rely on the springed shoe behind the jack for improving =
repetition.  This device is only effective with an unusual low hammer =
checking.  If hammers check too high, it simply won't come into action.  =
Also, in the unrestored examples of this action that I saw, hammer =
checking distance from string was about 25 mm.  And this produces a kind =
of "soft landing" touch feel (as would say Antares) that is very =
agreable.  Even that stop rail behind the hammers rest rail proved to =
improve repetition, when well regulated, by providing a shock to the =
back of the key, which then rebounds more quickly.  Funny : you can, by =
choosing appropriate felt density and regulating the heigth of that =
rail, voice the extra thump sound that it gives.  This appeared very =
useful to me, specially in the high trebble, whose sound is then much =
evened out (as the thumb in itself is very even) and improved in volume. =
 Drawback : this tends to cause a "hard landing" touch feel.
Strange : even with a 65g DW, the action feels light.
But if indeed there is not a  repetition performance comparable to that =
of a modern action (which, as Stephen Birkett noted, is seldom really =
needed in piano litterature), I can tell you that the gain in feel for =
control, especially at low levels, is tremendous.  No buffers between =
your finger and the hammer, and you really can regulate set-off at less =
than 1 mm from the strings without any problem.  I wouldn't want another =
action in my own piano.

Best regards

And thanks for converting my too huge jpeg.

St=E9phane Collin.





  ----- Original Message -----=20
  From: Richard Brekne=20
  To: Pianotech=20
  Sent: Saturday, June 07, 2003 10:59 AM
  Subject: Re: Hammer assist spring ?


  Grin... well I'll be shwagboggled by an Algorthian double winged =
dingbat ! Just goes to show its nearly impossible to have an origional =
thought in this world :)=20
  The attachment was like HUGE !!...   for those of you who want a quick =
veiw of this interesting action....=20

  =20

  Thanks St=E9phane.... why dont you give us some more background info =
on this picture.. where did you bump into this one for example... and =
what is its proper name ?=20
  This puppy is actually quite cute !... that spring has a nice =
combination
  affect of pulling the jack back into place as well. It tensions the =
jack
  and the shank in opposite directions so to some degree it would work
  together with that springed jack check to improve repetition. Tho it =
looks
  like the key would need to have enough back weight to fall back =
quickly
  enough.

  Neat action idea.




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