True it depends on the degree but the point of the comment was that subtracting the 1 mm from the string height - flange center pin difference will not place the hammer at right angles to the string only when the string plane is parallel to the keybed. It will accommodate some rise in the string plane toward the bridge. The amount of rise it will accommodate will depend on those factors you mention. David Love www.davidlovepianos.com From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Ed Foote Sent: Monday, February 08, 2010 11:17 AM To: pianotech at ptg.org Subject: Re: [pianotech] boring, (was Hammer strike line) Dale writes: Original hammers and shanks over centered a good bit. Our shop does not do it this way. My formula is :String height minus center pin height minus 1 mm in each section. I said, This will place the hammer at right angles to the string upon contact ONLY when the string plane is parallel to the keybed. What do you do when there is a considerable rise of the strings from the capo to the bridge? David asks: >>Why is that? Wouldn’t subtracting the 1 mm compensate for some rise in the string toward the bridge? I don't know, that would depend on the actual angle of the rise, and if it does, then it sets all the other sections out of square, no? and if the strings are parallel, the missing 1 mm will cause over-centering at the beginning of the hammers' life. I have seen quite a few pianos with a very sharp rise to the bridge. In those cases, new hammers bored short enough to create the 90 degree match to string would have been too short to regulate properly,(shanks way off the rests). It is sometimes necessary to hang the top section with an acute angle to the hammer, plus boring a short as possible. Regards, Ed Foote -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100208/2b439db1/attachment.htm>
This PTG archive page provided courtesy of Moy Piano Service, LLC