Hello, all.
Reading back through various posts over the years, I notice there seems to be a number of schools of thought about how tuning pin torque should be measured.
Averaging clockwise/counterclockwise, with strings, with no strings, etc.
Averaging seems logical, but doesn't seem to pan out in reality. Say there is a lot of rendering resistance pulling up (clockwise) but very little in the downward/push direction (counter-clockwise). For example, a grand piano in a practice room here reads 85in/# in the pull but less than 15in/# in the push direction. The pin doesn't hold over even a short time, but averaging them, math says this should be fine: 80+15 = 95/2 = 47.5. Minimal but should hold. Subtracting 80-15 = 65; should definitely hold. Removing the string eliminates resistance, but can't tell you what the factors of string rendering would be, and they are considerable.
Has anyone come up with a better method of determining real torque; not just what it should theoretically be, but how to arrive at it in real life? Perhaps down torque as a percentage of pull torque or net torque. Maybe this has already been satisfied, but I can't find it anywhere, just a lot of discussion. I have historically made this determination by manual manipulation, but I want to be able to present and support my findings in a way that is quantifiable.
Dave
------------------------------
Dave Conte, RPT
Piano Technician in Residence
The University of Tennessee
College of Music
Knoxville TN
(817) 307-5656
Owner: Rocky Top Piano
------------------------------