I suppose its a ball park figure that works reasonable well enough on enough pianos that it gets shuffled around enough til it becomes accepted as a norm. Still seems usable enough if one modifies it just a tad to bring the shank into the same plane as the string. No doubt there are times when this wont work either... but it seems like one gets just a bit closer. I haven't got this clear in my mind yet however, as I've just always taken it on faith that the horizontal shank at impact with a hammer perpendicular to the shank was more then good enough in nearly all cases. Clearly any change in bore length needs to be looked at closely with regards to what impact it will have on regulation. In this case I increased bore length from the existing by about 3 mm. This worked out both by the advice I got from my two buds down on the continent, and by more empirical based checks on the action. Hints that were obvious... turned up drop screws and let off buttons with nearly no room left between the tops of the buttons and the underside of the rail. Cheers RicB That sounds to me like a good description of fudging from start to finish. Heaven knows where this superstition concerning the horizontal shank at impact arose, but there is no scientific basis for it any more than there is any science behind the downward rake of the hammer on the old Steinway uprights. The angle of the shank at impact, whether on a grand or an upright, is determined by the geometry of the whole set-up, which was generally carefully worked out to reduce the entrance height or (on an upright) the case depth to a minimum. The majority of grands I have worked on are designed to have the shank exceed the horizontal and the hammers bored accordingly. JD
This PTG archive page provided courtesy of Moy Piano Service, LLC