Baldwin SF-10 grand with acu-just hitch pins

[pianoguru at cox.net]

---- AlliedPianoCraft <AlliedPianoCraft at hotmail.com> wrote: 
> I have just finished the pin block on a Baldwin SF-10 I am rebuilding. Does anyone know how to set the plate height on this piano. 

When I was there in the Baldwin factory, they were set up to adjust the plate height such that when the correct bearing is set, the string will be at about the center of the pins exposed height, the thinking being that you have equal room for adjustment in either direction.  Personally, I would prefer to end up with the strings as low as possible on the pin, but with sufficient margin to be confident that none would be totally down on the plate.  In other word, set the plate, as well as you can determine it to be, such that the string is a little on the low side of the halfway mark, when the bearing is what you want it to be.  Keep in mind that you are checking the unloaded bearing, while the final Baldwin specs are for the loaded bearing.  

This works out pretty well in the bass, and lower tenor ranges, but it could be a problem in the high treble.  I have seen some new Baldwin's, especially SF-10's, with excessive front bearing, and negative back bearing, in the high treble.  The Baldwin old-timers would tell you that the balance of front and back bearing is irrelevant, as long as the over-all bearing is correct.  I would take exception to this, especially when it goes to the extreme of having negative back bearing.  With the old Baldwin bubble gage, each mark on the gage is roughly about 1/2 degree in terms of angle of deflection.  I have seen 5 times the amount of front down-bearing, and 4 time the back bearing deflecting upward.  The over-all bearing measured correctly with their bubble gage, but the end result was 5 times the downward bearing in the front, and 4 times the intended downward bearing, lifting up at the back of the bridge.  That was OK in the factory, but if I found that condition in a piano I was rebuilding, I would shim up the pinblock, at least enough to get positive down bearing on the back.  That would mean that I would have to alter the hammer bore distance, but better that than negative back bearing.

Frank Emerson