Very interesting experiment. Your "string offset angle which is often below 10 degrees" - the string offset being the angle that the string makes as it goes from the speaking length and bends around the first bridge pin? And that angle being controlled by the placement of the rear bridge pin. Am I right? Just making sure. Thanks Terry Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com ----- Original Message ----- From: "Ron Overs" <sec@overspianos.com.au> To: <pianotech@ptg.org> Sent: Tuesday, September 05, 2000 5:48 AM Subject: RE: False Beats > David, Ron, Richard and list, > > David wrote; > > >. . . . I can think of hundreds of grands, especially > >Japanese/Korean, where I could visibly see the string drop to bridge cap. > >Another tap wouldn't move it. > > So often these makers use bridge pin inclinations which are insufficient and a string offset angle which is often below 10 degrees. > > I learned a lesson the hard way a recently. Ten degrees of string offset angle and twenty degrees of pin inclination certainly works well. > > In July we completed a new piano for the Australasian Piano Technicians Convention. The piano was a modified Samick 225. We designed a new scale and made new bridges, along with many other design changes. This piano was the first to get our new grand piano action. > > However, during the design phase of this project, which was rushed to say the least, I made an error in a spreadsheet formula while working out the bridge pin locations to set the string offsets. Unfortunately, this error resulted in string offsets which were pretty close to zero in the top two sections. I discovered this problem just before the piano was to be strung, and too close to the convention to rectify. Therefore, we were compelled to string the piano, warts and all, since it was to be an exhibit at the convention. > > I was not too pleased with the tonal qualities of the treble section. While it was just acceptable, it had none of the clean tonal qualities which I had expected. Indeed the piano was so false as to be difficult to tune. After the convention we stripped the piano down and recapped the offending sections. We are now delighted with the tonal qualities of the treble. The only difference between the two bridge caps was the string offset angle - yet the tone was radically improved. For the second take, the bridge pin positions were transferred from the spreadsheet to a CAD drawing of the piano. The drawing scale was adjusted to produce an accurate 100% print out on our Epson inkjet. The print out was placed on the blank bridge caps, which allowed us to punch the marks through to the bridge cap. Using this system we were able to get the highest bridge pin location accuracy we have had to date. I have suspected for while that insufficient string offset angle to contributes to falsen! > ess. The bungled bridge cap saga prove it> > Ron O > > Overs Pianos, Sydney Australia > ------------------------------- > Email: sec@overspianos.com.au > Website: www.overspianos.com.au > ------------------------------- > > >
This PTG archive page provided courtesy of Moy Piano Service, LLC