[pianotech] Beckets

[David Skolnik]

Danger! Danger!

If you smart boys can't avoid talking past one another, what hope is 
there for we sub-mortals?

Jude said nothing about pin angle, though that was a point raised by 
Ron in responding to the original photograph submitted by Richard Ucci

>Date: Thu, 01 Oct 2009 08:16:51 -0400
>From: Richard <richard.ucci at att.net>
>Subject: [pianotech] Pin height

>Oh, and they [the coils] likely wouldn't be "loose" if the pinblock 
>had been drilled at a more reasonable angle.
>Ron N
>Thu, 01 Oct 2009 15:08:20 -0500

Perpetuating my nitpiky pathology, the angle of the pin in the block 
is less of an issue, or rather, at least theoretically, determined by 
the inclination (angle?) created by the string between the front 
bearing and the take-off point.  You have multiple variables with 
their own ranges of tolerance.  The parameters determining the 
desirable  distance of the take-off point (coil) from the plate are 
functions of pin flex and torsion and allowing room for some further 
corrective tapping (practicality).  The control of the pin-distortion 
elements (flex & torsion) impact the range of tuning techniques at 
our disposal.  The more the system precludes such distortion - by 
maximizing stiffness - the more tuning is limited to actually turning 
the pin such as is the case with tuning pins contacting front of 
plate hole.  The draft angle, in turn, is tied to a frictional coefficient.

Once you know that take-off height, and assuming your theoretically 
ideal take-off angle would be 90 degrees, the pin angle would be 
determined as I described above.  Its seems most everything else is a 
function of generating safe tolerances - coils not contacting plate; 
take-off angle not LESS than 90 degrees,(creating stress-point where 
string begins to over-wind coil above).

In theory, as the take-off point moves closer to the plate, we would 
want to be able to revise the pin angle, to maintain a 90 degree 
take-off.  There must be some range of angle, more than 90 that would 
still not have a negative impact of the capacity to maintain tight 
coils, past which, Ron's statement:
>The angle relationship of the pin to the string, determined in part 
>by the angle of the pin in the block, *is* the part of this that 
>affects the process of getting tight coils.
is certainly correct.

But I'm not sure I understand his last question: "Why would having to 
drive the pin deeper be a problem?"  which, in turn was a response to 
Jude's statement: "More coils can allow for the string to exit the 
tuning pin perpendicular towards the front bearing thus allowing for 
a tight coil without sinking the pin deeper than less coils would allow."

Earlier in the poly-thread, driving pins deeper was suggested as a 
way to correct the condition presented in the photograph.  As I said, 
in an earlier response, if the pin-torque was already tight in the 
photo configuration, driving pins could produce unacceptably (to me) 
high torque readings. (It would, however, probably re-establish the 
correct draft angle.)  That would be my concern, even if there was no 
issue of pins protruding from the underside of the block.   It might 
be that such a change in pin depth would not generate such results in 
Ron's pianos.  I don't know.

I didn't bring up the question of whether a pin, angled back in a 
block, with a take-off angle in excess of 90 degrees, would be any 
stiffer, due to the different vector.

Boy, am I in trouble.

David Skolnik RTT
Hastings on Hudson, NY






At 08:39 AM 10/7/2009, you wrote:
>Jude Reveley (Absolute Piano) wrote:
>>Who said anything about pin angle relating to tight coils? I think 
>>you misread my post.
>
>A choice of pin length, pinblock composition, drilling fit, and 
>driving depth would still let you put the takeoff point of the coil 
>at any height you like above the plate regardless of the number of 
>turns on the coil. And the string draft angle does relate to pin 
>angle, or should. The angle relationship of the pin to the string, 
>determined in part by the angle of the pin in the block, *is* the 
>part of this that affects the process of getting tight coils.
>
>Why would having to drive the pin deeper be a problem? I covered 
>that with "choice of pin length", "pinblock composition", and "drilling fit".
>
>Ron N