[CAUT] Steinway D elevations

[Douglas Wood]

I have a question for those of you with experience in custom boring  
hammers. Our heavily-used and very nice D#542295 has an elevation  
challenge that I'm working on. The piano generally works very well,  
but has a reputation for being "tricky". I think part of this is due  
to the following problem:

The string height in the upper tenor is nearly 1/8" higher than the  
sections on either side, and note 88 is 1/8 lower than the majority  
of the piano.

So, the regulation does work, but that central section has the shanks  
a bit high off the rest felts, and the rest of the piano has shanks  
nearly on the rest felts. As I say, it works, but I'm considering a  
custom boring job to match the bore to the string heights. I will, of  
course, revisit stack height before boring, as I'd like to do the  
figures only once more.

The real question is, how far from nominal bore spec can one go  
before encountering other problems? And should I follow the string  
heights closely all the way across, or do more like Steinway does,  
and allow regulation to take up some of the variance?

Doug Wood