Baldwin accu-hitch pins

[David Love]

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Dale:

My conversations and classes that I attended with David Hughes (if I =
remember correctly) led me to believe that he prestressed the board =
under the central plate strut by 3 mm and then set the bearing dime, =
nickel, quarter, in low tenor, mid-range, treble, respectively.  That =
seemed to pretty much be his method without additional measurement.  I'm =
sure he arrived at this method by much experience, but he didn't seem to =
sweat it beyond that.

David Love
  Dale:

  ----- Original Message -----=20
  From: Erwinspiano@AOL.COM=20
  To: pianotech@ptg.org=20
  Sent: January 19, 2002 5:46 PM
  Subject: Re: Baldwin accu-hitch pins


  Subj:Re: Baldwin accu-hitch pins=20
  Date:1/19/2002 3:28:10 PM Pacific Standard Time
  From:davidlovepianos@earthlink.net
  Reply-to:pianotech@ptg.org
  To:pianotech@ptg.org
  Sent from the Internet=20



         Dale:

    I believe the Baldwin instructions call for setting the bearing at =
zero degrees to begin with.   After pulling the piano to pitch you then =
start at the bottom of the tenor (no bass strings yet).  Tap down note =
21 - 35 to 1/2 degree, 36 - 53 to 1 degree and 54 - 88 to 1 1/2 =
degrees--in that order.=20


  >>>>>>>> Thanks David now this is starting to make some logical sense, =
to me at least. Wow 1/2 half degree isn't much for starters on a board =
with real crown values. An easy way to calculate 1&1/2 degrees of =
bearing is to measure the rear string length from the front bridge pin =
to the aliqot i.e. measure any tenor back scale length say of 6 inches. =
Multiply by.026 =3D .156". So 1/2 degree would only be .50. It would be =
easy to deflect the whole central portion of the  board by that much by =
just leaning on it with hand pressure. By the way 1 degree is calculated =
by .017 times the length.

  Thus, the 1 1/2 degrees that you set the upper teble range to is on a =
semi-compressed=20

    board, at least to the degree that setting the bearing on the =
previous sections will compress it.=20


  >>>>> True
    So notes 54 -88 are actually set at greater than 1 1/2 degrees if =
you were=20

    measuring from the point before the board had any downward pressure =
it.


  >>>>Yes but the net result would be less than that because of board =
compression. This would be barely enough pressure to"take the slack out =
of the board " as John Hartman says ,let alone utilize all the crown =
that was so carefully built into it. What I want is to press the board =
fimly so that it is spring loaded enough to push back against the =
string. When this happens the board are in firm resistance to each other =
and this is when I believe that optimum power/sustain are approached, =
especially in new fully crowned boards.  With respect to my method of =
setting bearing ,at the point the Baldwin boards bearing is set is the =
point at which I would probably start adding 1 1/2 degrees of bearing =
but not exeeding 1/4" on the longest string lengths.

         Moreover, if you were to go string by string, the measurable =
bearing after you got=20
    to the top would be something less than your initial target.  The =
question seems to be, when the board is already set with some bearing, =
but perhaps the wrong bearing, how do you approach the problem?


    >> I agree.  A bit of a sticky wicket  =20

  Can you simply go through and correct the bearing to read 1/2, 1, 1 =
1/2 degrees=20

    respectively?  I often wonder whether we fret over this a bit too =
much


  .=20
       >>>>>>I respectfully have to say I don't think so. If you have =
the chance to change one of these and  improve it in the process you'd =
answer your own question.

     I've heard good sounding boards with a variety of downbearing =
measurements. =20

    Though I have not heard one of David Hughes' boards, the impression =
I get from him is that we sweat over this a bit more than is necessary.  =
The factors that go into a good sounding board are obviously greater =
than just the bearing measurements.  Teasing out the variables is =
difficult, to say the least.


  >>>>Yes but is bearing where you'd have me sweat less on if it was =
your board project? There are several obvious primary factors that we =
all consider essential. Good construction,materials ,crown ,adequate =
bearing,reg. and of course voicing.
       Davie Hughes and have talked bearing at length and our methods =
are very similar if not identical. His boards sound very fine. Wonderful =
sustain and color.  I have to say he may have been understating it a =
bit.
      Bearing/plate set up setting in my shop takes a good long time as =
I consider it a VERY primary and critical component of making the whole =
system work well. I've looked at a lot of  torn a part pianos over  the =
years and 90% of those that I liked the best had significant even  =
measurable bearing and crown. The other 10% are anomallies. I.e  Board =
stiffness due to mass not crown or bearing
     I"ve also had the advantage of a few less than stellar results =
(which is aggravating) that I could lay at the feet of uneven or =
inadequate bearing/panel compression that when remedied the tonal =
results were greatly improved.
    To me a new board with inadequate bearing is like a fine new car wth =
only a gallon of gas in the tank. It won't take you very far.
    Thanks again for enlightening me to the Baldwin method. I now have a =
better grasp of there concept though I consider it misguided.
       =20
       Best---Dale Erwin



    David Love




      ----- Original Message -----=20
      From: Erwinspiano@AOL.COM=20
      To: pianotech@ptg.org=20
      Sent: January 19, 2002 2:07 PM
      Subject: Re: Baldwin accu-hitch pins


      In a message dated 1/19/2002 11:23:14 AM Pacific Standard Time, =
RNossaman@KSCABLE.com writes:



        Subj:Re: Baldwin accu-hitch pins=20
        Date:1/19/2002 11:23:14 AM Pacific Standard Time
        From:RNossaman@KSCABLE.com
        Reply-to:pianotech@ptg.org
        To:pianotech@ptg.org
        Sent from the Internet=20




        >
        >  Ron (somebody) tell me what I'm missing on the acujust in a =
way I can absorb
        > it. What's that you say? not possible. hmmmmmmm
        >       =20
        >        Dale Erwin


        Dale,
        I'm not sure what the question is here. Like you have adjusted =
plate height to
        fine tune bearing, you can do the same thing section by section, =
or note by
        note with the hitch pin adjustment. Your initial plate height is =
determined
        just like you would normally do it, only your back scale target =
isn't the top
        of an aliquot, but a vertical position on the hitch.


      Hi Ron
        Ok I get this sort of but the place where I'm hung up is that as =
you start driving the strings down on the hitch your bearing increases =
as does the amount the board is compressing as you go. Just like in =
pitch raising. So how do you know when enough is enough and when do you =
know that there is enough ,of the desired deflections so often =
discussed. Meaning a 1 to 11/2 degree angle of deflection depending =
where in the scale we are talking about.
      Dale
      If you shoot for somewher

        around 4mm up the hitch as a target, you have some room for =
final vertical
        positioning as you find necessary.=20

      Ron
         Once again how could a person possibly know what the final =
position is?


      Does that make sense? =20
           Ron

           Uhhh not yet Ron.  I must be coming at this from a really =
strange angle of comprehension. I took Stacy Yokums class in Reno and he =
couldn't answer my question either. I wasn't the only one asking it =
either.
        Let me try another way by explaining where I'm coming from.
        Ok Take a new board and new set of too tall bridge caps. Install =
plate and cut the tops so that without any load on the board you have a =
1 degree angle of deflection in the lower tenor rising to 1& 1/2 degrees =
thru the tenor right  up to note 88. Now install all the strings from =
the tenor /bass break to 1st capo section at. Tune these up to pitch. =
Before you string further take a bearing string and check the remaining =
deflection. Meaning once again that the soundboard is sinking under down =
bearing pressure as we go. If done this way I can guarantee an =
insuffiecnt amount of bearing to drive the treble in your shiny new =
board. The bearing string will probably touch bridge and aliqot at the =
same time or almost but that isn't enough bearing for trebles.
          In fact I you can't even read much deflection with the string =
at all. Unfortunately this is the very method Nick Gravagne outlined in =
the journal many years ago and it doesn't work unless you pre- stress =
the board some. He didn't correct or I should say amend it and I only =
found out he was using pre stressing and the 1 1/2 degree angle of =
deflection in one of my conversations with him a year or so ago.
           MY point oh yes is how in the acujust system does one =
approximate total and adequate deflection with any confidence that your =
not creating the problem I described above.=20
         My answer so far is that you can't. Its more of a guesstimate =
than I'm willing to make until somebody can give me some clarification.
        Does this help to see my angle of deflection!!!!!!!
                =20
                           Dale Erwin







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