Jon, I suggest an alternate repair. Reshape the original insert and have the machinist who is working with you check the hardness at the crown. It should be around Rockwell 40. If not, explore having it hardened. It could end up costing less to harden the insert rather than machine a slot. Also, the water hardened drill rod you obtained from your local supplier is probably too hard and may cause buzzing at the duplex. Additionally, I've always felt that the capo should have as few mechanical "interruptions" as possible. Let me explain. It is known that when energy passes through different mediums, an energy reflection is created. This is experienced by the submarines sonar when the sonar wave hits an area of different water temperature. It is, in effect, a different medium and a reflection is received back. The drill rod is a different medium from that of the cast iron, as well as the microscopic gaps that are sure to exist at the union of these two parts. An energy reflection from the vibrating string is certain to reflect back into the string. This reflection is going to be out of phase, creating an impedance imbalance that contributes to an ugly sound. This "pinched" sound can also be heard with laminated bridge caps or laminated soundboards. Roger Gable ----- Original Message ----- From: "Jon Page" <jonpage at comcast.net> To: <pianotech at ptg.org> Sent: Sunday, September 19, 2010 9:53 AM Subject: Re: [pianotech] YC Capo Bars >A post last month showed the string impressions in the v-bar insert > on a 1996 Weber grand. > http://ptg.org/pipermail/pianotech.php/2010-August/027631.html > > I have a 1/8" rod to install into a machined slot. Photo attached. > The machinist will level an area and mill the slot with a 1/8" round bit. > Should the depth of the slot be .040" or more like .060"? > -- > > Regards, > > Jon Page
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