1-29-1997                                                                                      TS039D 

PROCEDURE TO ESTABLISH PROPER DOWN BEARING OF STRINGS ON BRIDGES OF BALDWIN GRAND  PIANOS DESLGNED WITH HOLLOW VERTICAL (ACU-JUST) HITCH PINS 

These conditions must exist before bearing can be established:

1.All strings associated with the treble bridge must be in place,  (Bass strings to be installed later.)

2.  These strings must be tuned to A-440 pitch.

3.  All strings on the treble bridge must be set at proper height on their hitch pins to read zero (0.0) bearing at the bridge.  Follow this procedure; begin at treble end of treble bridge with note #88 and work toward bass.  Lift wire and raise tension of the strings on the first ten (10) notes,  Then raise wire and adjust tension of the next ten (10) notes and proceed on until all wire is adjusted in this manner on the treble bridge.

Procedure for string height adjustment.

1.  Become familiar with bubble gage adjustments and application as shown with the attached illustrations,
2.  With strings at normal tension, begin with strings at the bass end of the treble bridge and work toward the middle,  Set bearing values as shown in the following chart on specified notes only.  Tap the string down by placing the tool over the hitch pin, resting on the wire,  with the bubble gage held onto proper strings with the magnet built into its base, tap the setting tool with a small hammer to lower the string to achieve a proper bubble gage reading.  If the string is too low, raise the string, using a coil lifter and leather or felt to protect the plate finish.

Scale                      SA(5'2")    ST(5'8")    SC(6'3'')    SF10(7'0")    SD10(9'0'') 
Notes to be set            27-44       27-43       23-40        21-39           21-35 
Bubble Deflection          1 divis.    1 divis.    1 divis.     1 divis.         1 divis.  

3.  After strings associated with the notes which were adjusted in the preceding operation have been set, proceed on with notes listed in the following charts.

Scale                      SA(5' 2")   ST(5'8")    SC(6'3'')    SF10(7'0")     SD10(9'0") 
Notes to be set            45-53       44-53       41-53        40-53          36-53
Bubble Deflection          2 divis.    2 divis.    2 divis.     2 divis.       2 divis.

Scale                      SA(5'2")    ST(5'8")    SC(6'3")     SF10(7'0")     SD10(9'0") 
Notes to be set            54-88       54-88       54-88        54-88             54-88
Bubble Deflection          3 divis.    3 divis.    3 divis.     3 divis.            3 divis.

4,  Install bass strings and set at zero bearing,  Then adjust bearing according to the following chart.

Scale                      SA(5'2")    ST(5'8")    SC(6'3")     SF10(7'0")     SD10(9'0") 
Notes to be set            1-26        1-26        1-20         1-20               1-20
Bubble Deflection          1 divis.    1 divis.    1 divis.     1 divis.           1 divis 

5.   Retune piano to A-440 pitch.

CONCLUSION:

1. Bearing adjustments should only be made when the piano is maintained under proper climatic conditions.  (Humidity 35% - 45% with temperature 70 - 75) 

2. The procedure and bearing gage must be applied in the order established. 

3. A bearing value, previously set, cannot be rechecked because the accumulated force of all strings on the bridges will lower the soundboard and reduce the settings which were originally set.

4. Pianos equipped with the vertical (Acu-Just) hitch pins are designed to function with a minimum positive bearing at the bridges, compared with other pianos with string rests and angled hitch pins.

*Hand written note at bottom: 1 div. = .005" shim thickness with a Baldwin Rocker Gage.