tuning pin torque

[Terry]

If the piano is unstrung, I measure torque directly, turning either way. If
the piano is strung, I measure clockwise and then counterclockwise torque
and average the two together - I figure that should subtract the string pull
effect. And I think your figure is in the ballpark of what I have observed
the difference to be.

Terry Farrell


> In measuring and reporting tuning pin torques what is the normal
> assumption about the contribution of the string to the measurement?
> This will provide about 35in.lb helping of hindering tuning pin
> torque depending on the turning direction during the measurement.
> Typical values are often mentioned, eg. "loose pins are when torque
> is <50in.lb" "ideal tuning pin torque is around 100-150 in.lb range",
> ">200in/lb torque is tight pins" and so on, without saying if these
> are intended to be true torque (i.e. no string), or clockwise vs
> counterclockwise with a strung pin at tension. The latter will vary
> +/-35in/lb or so [for a typical full tension string]. I suspect the
> reported pin torque values probably refer to counterclockwise and
> strung pins, since it's more likely this is how they would be
> measured [although not when re-pinning a pinblock of course]. So a
> torque of say "50in.lb" woulld actually be a true torque of around
> 85in.lb with just the pin. But I'm guessing this is the intent of the
> reported numbers.
>
> Stephen
> -- 
> Dr Stephen Birkett, Associate Professor
> Department of Systems Design Engineering
> University of Waterloo, Waterloo ON Canada N2L 3G1
> Director, Waterloo Piano Systems Group
> Associate Member, Piano Technician's Guild