Hi JD. Well this sounds kinda interesting... and I am most certainly willing to give it a try... sounds easy enough to accomplish really. That said... most of the advice I've seen coming through the woodwork goes along the lines that if the hammer is not perpendicular to the shank at contact with the string.... then thats where the energy loss kicks in. At the Yamaha concert tech academy they specify 90 degrees. I've heard argumentations in favour of a 2 degree rake, in both directions for that matter but thats always been about the shank flexing. Be that as it may... let me see if I got this right. Grands only to begin with.... just so that thats out of the way. String to key bed height minus hammer center to key bed height determines bore length as usual yes ?... then rake is determined by the offset from parallel that the string plane to the shank at string contact for the resulting bore length ? The bore length should put the hammer shank at parallel to the key bed at string contact yes ? So string offset to the shank at contact can be figured from the key bed plane then ? Cheers RicB At 22:37 +0100 15/2/08, Richard Brekne wrote: >...I have to admit I have never taken into consideration the angle >of the strings to the key bed... I pretty much stick with a >perpendicular to shank hammer... tho I am most willing to listen to >reason why I should rather choose hammer perpendicular to string. It is most important, in the extreme treble especially, to have the hammer strike the string exactly at a right angle in both planes, otherwise there will be loss of energy. On many grands the strings in the top section are at a considerable angle to the horizontal. The Bechstein C I am working on surprised me by being an exception to the rule, but the angle has to be measured and factored into the bore. >I also tend to go for a constant rake ( 90 degrees to shank)... Why? That is by no means standard. Many pianos require a 2 degree outward rake and some older models require an inward rake. With a Bechstein you can mess about with the rest rail but that doesn't mean you're not introducing errors in the geometry. On pianos with individual rest cushions things have to be just right. > ...and vary hammer bore to match string distance to keybed. Well, as I hope I've made clear, that's not good enough. You'll get away with it through most of the scale but in the treble not only is it critical to have a right angle but if you don't measure the slope of the strings you won't be able to calculate it so that you do get a right angle. It's a very common omission and it's the reason why so many people can't get the treble right, especially on Bechsteins and Blüthners. Now if you're lucky to have a piano with the strings perfectly horizontal in the extreme treble, well and good, but it has to be known. On most pianos the slope of the strings diminishes to an insignificant amount by the time you get to the top break, but by that time, you're out of trouble anyway. JD
This PTG archive page provided courtesy of Moy Piano Service, LLC