Dan, The rounded / pointy top hammer with a smaller strike point stresses the wire less - that is why keeping them filed helps reduce string breakage. I don't know that a super point would be any better than a proper point for the particular part of the scale - but it's the string grooved hammers that drive the string with a flat shape that seem to be the worst. Regulation can help or hurt - if the letoff is too close or the jacks are too far under the knuckles or the hammer blow is too large, there is more stress. Especially letoff, which is why people so often recommend lowering the letoff. How effective this is, and how much it should be lowered, would depend on the piano and how much compression of the action and letoff button punchings happens on the really hard blows. But the letoff will move as much as 2mm closer on fff blows with many pianos. But then, some pianists just have a talent for breaking strings, and those who become teachers tend to teach their students to break strings as well. Don Mannino From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of bergpiano Sent: Wednesday, February 23, 2011 5:18 AM To: pianotech at ptg.org Subject: Re: [pianotech] Breaking Kawai treble strings Don, Thanks for the great suggestions. I did shape the hammers with string installation. Could you go into a little more detail about how the regulation would contribute to string breakage. I would assume it invloves changing power and velocity. For the benifit of Paul and myself and perhaps others I think it would be good to look at this a little more precisely. Thanks Dan ----- Original Message ----- From: Don Mannino <mailto:donmannino at ca.rr.com> To: pianotech at ptg.org Sent: Tuesday, February 22, 2011 10:46 PM Subject: Re: [pianotech] Breaking Kawai treble strings Daniel, Did you also shape the hammers? The hammer shape and the regulation will affect this as well. But in some cases, people just break strings. Your assumption that they aren't playing it that hard is not supported by the fact that the strings are breaking - someone there likes the piano, and is working it very hard on a regular basis, I think. One other trick that can be telling is to raise the one balance rail glide screw at the treble break (near where these pianists tend to break the most strings) all the way up. This is not usually noticed by the pianist, will not affect the tone or touch at all in softer playing, and it takes away a little of the aggressive impact of the heavy handed pianist. Unfortunately the strings have now become fatigued again, so no matter what you do they will be breaking. It is best if the hammer shape and regulation are addressed at the same time as the new wire installation. Don Mannino From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of bergpiano Sent: Tuesday, February 22, 2011 5:11 AM To: pianotech at ptg.org Subject: [pianotech] Breaking Kawai treble strings I have a customer with a Kawai GS-70. After it arrived about three years ago treble strings started to break while playing, about once every 2 to 3 weeks. I talked to Kawai techs and decided to restring the capo section. I used Kawai's stringing chart for decimal wire and sanded the capo to shiny smooth. I also filed the hammers. After a short while strings started to break again every month or two. Now they are breaking about one every 2 to 6 weeks. The breaks have always been at the capo. What am I overlooking? I would not say the players strike overly hard. It is in a private school. Students and teacher (mostly teacher) have broken wire. Classical music. Could hammer position have a bearing here? Hammers are original. Regulation? I need some brainstorming here! Many thanks, Daniel Berg RPT -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20110223/585344e3/attachment.htm>
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