downbearing question

[Stéphane Collin]

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Hi Dale.

Thanks for your response.  I re-read the nice article of John Hartman =
about setting downbearing.
In this 1864 Pleyel, the rim seems to be shaped in order to favour a =
dome in the soundboard culminating at the place where the bridge =
supports the strings of the section from high tenor to low trebble.  The =
rest appears to be flat.  Ah, and the grain of the board runs parallel =
to the spine, while the ribs (12 in total, and small ones) run =
approximately perpendicular to the tangent at a point of the long bridge =
curve.  You were right, even after shimming, not much crown is left in =
the board.  I understand that this is a warning that I should be very =
careful with downbearing.

Thanks again for your good energy.

Best regards.

St=E9phane Collin.
  ----- Original Message -----=20
  From: Erwinspiano@aol.com=20
  To: pianotech@ptg.org=20
  Sent: Sunday, July 31, 2005 4:43 AM
  Subject: Re: downbearing question


      Stephane
     Well I saw no responses to the can- o - worms post ..........grin
     SO  I kind of hate to wade into this but I'll try to make it as =
simple as my mind usually works.  If I translate what your saying =
accurately, your concern is that your  total residual lowell gauge =
bearing reading of 6 marks on the gauge is too much. Is this right? 6 =
times .003 =3D.018 or 1 degree
     If so this would would be a great deal of bearing for an old flat =
soundboard. IMHO.
    I'll refer you to setting bearing to 1995 PTJ articles by John =
Hartman for (One)  concise  method of setting bearing & also general =
guidelines.
      It is not the only method but the one I subscribe to presently as =
do many others
    In a fully crowned board It would be common to detect 2 plus degrees =
of bearing in the top trebles(tweeters) 1 & 1/2" in the Alto =
region(middle of the board)  & 1/2 degree in the low tenor( the chello =
section). Trebles require more pressure stiffness to drive high =
frequency. Bass  sections virtually none to make bass. But I like some =
(1/2degree)on larger pianos without cantilevered bass bridges.
    More than any of the above . Does the piano sound good ?? This tells =
a huge story. Has the board assumed a flat compressed condition. Meaning =
the crown has been squashed down to  a flat state & not turned inside =
out or upside  down or concave.=20
    If a board of this age has been shimmed  it is a falt board  & IMO =
there will not be an appreciable crown to work with so only small =
degrees of bearing are prudent or tonal distorations & maladys of all =
kinds can develop. Amhik
    I dont' know if this helps any one but there it is.
     & It's JMHO
    Dale Erwin
   =20

    Hello list.

    This old 1864 Pleyel (again) has many features which I think are =
quite straight forward.
    The rim and the ribs are shaped so there is nearly no crown in the =
bass bridge regio, few in the tenor, lots in the alto and again less in =
the high trebble.  In the original setting, downbearing followed this =
pattern : nearly no on the bass bridge, few on the low long bridge, lots =
in the trebble and less again in the high trebble.
    My question is : in such an arrangement, can we set more downbearing =
in this alto area than if the downbearing were spread on the whole scale =
?  How much could I put there ?  For now, after soundboard shimming, =
there are as much as three graduations on the Lowell gauge, in front =
bearing and in rear bearing.  I'm used to consider this quite much.  Any =
opinions ?

    Best regards,

    St=E9phane Collin.=20


  Erwins Pianos Restorations=20
  4721 Parker Rd.
  Modesto, Ca 95357
  209-577-8397
  Rebuilt Steinway , Mason &Hamlin Sales
  www.Erwinspiano.com
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