There is nothing magical about a string deflection angle of 7.5˚ across the V-bar and it may or may not be appropriate for your particular piano. The minimum angle necessary to ensure reasonable termination of the string speaking length is function of the distance between the V-bar and the bearing bar or, in this case, the pressure bar. I call this length of string the "frontscale." If the centerline of the pressure bar is very close to the centerline of the V-bar--a frontscale length of, say, 10 to 15 mm--the deflection angle does not have to be very high; 5˚ to 7˚ is probably adequate. If the frontscale length is some greater--say 20 to 25 mm--the deflection angle should be more like 8˚ to 12˚. Assuming, of course, that you want to avoid string noises, false beating and tuning difficulties. If the frontscale length is more like 30+ mm the deflection angle should be at least 15˚, possibly more. Again, assuming you want to avoid string noises, false beating and tuning difficulties. Keep in mind that the closer you set the bearing bar to the plate the more tendency the strings will have to walk down the tuning pins as the piano is tuned. ddf Delwin D Fandrich Piano Design & Fabrication 6939 Foothill Court SW, Olympia, Washington 98512 USA Phone 360.515.0119 — Cell 360.388.6525 del at fandrichpiano.com — ddfandrich at gmail.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson Sent: Saturday, July 30, 2011 10:42 AM To: pianotech at ptg.org Subject: Re: [pianotech] tightening the pressure bar Ron, I appreciate the detailed information - also, Isaac Sadigursky took the time to call me at home to tell me that the ideal angle was 7.5 degrees - thank you Isaac. Has anyone accurately measured this angle or must it be calculated? I could probably set in on a compass, compare and guess close enough
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