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David and list
all your questions are good ones and since I started the ditch the =
bushings campaign allow me to interject one potent argument and or bias.
Any tuner that has ever tuned a good original 20's stwy or other well =
fit piano has found that they tune remarkably well and flaggpoling is =
essentially a none issue. The pins render as better or at least as =
easily as any bushing fit block and the pins are not leaning against the =
plate(even after all these years) because of a good tight plate =
flange/block fit and this is a piano system that has endured for how =
many years?
It seems to me that any piano that has a a good block to plate flange =
fit ( and 40 screws)should be able to duplicate the stable and tunable =
Steinway style system.=20
As others have said one of the advantages to bushing is a =
dust/liquid barrier. I like Willis Snyder's idea of some form of wood =
colored plastic insert for those of us who might need that for school =
church or bar applications.
I addressed the issue of directional force in my first post on the =
subject.
Dale Erwin
----- Original Message -----=20
From: David Skolnik=20
To: pianotech@ptg.org=20
Sent: Saturday, May 12, 2001 10:26 AM
Subject: Re: Ditch the tuning pin bushings
Dear All-
This thread is extraordinary for the range of issues it contains, and it =
would be a shame if it dissipates before, at least some of these issues =
crystallize (didn't want to go so far as to say resolve). There is =
undoubtedly some overlap in the following.
The Issues
How do the 'Lines of Force' differ in an openface block; bushing-less =
covered block; covered block with bushings?
Do the 'lines of force' of a bushing-less block change if, over time, =
the pins, en masse, begin to contact plate? Would such an occurrence =
necessarily be due to poor flange fit, or could either poor top fit or =
soft wood be factors?
How much pressure against what resilience factor (durometer?) would be =
required to have an impact on these "lines of force'? At what point =
does 'support' begin to alter function?
Would you assume that a new or newly rebuilt instrument without bushings =
in which tuning pins already contacting plate is starting out with an =
acceptable alteration in its design parameters? =20
What is the intended design purpose of plate bushings? Which are =
unintended side effects?
- Dust and beer repellant
- Centering of drilling for tuning pin
- Support against flagpolling / springing
- Alteration of 'lines of force'
- Contribute additional torque to rotation of pin
How would intended purpose dictate material employed (soft wood, hard =
wood, delignit, plate contact) ?
How do tuning pin bushings contribute or detract from TUNABILITY, as =
opposed to tuning STABILITY?
To what degree (if any) is the springing / flagpolling tendency a =
valuable tuning tool?
How does the density of the pinblock material used with a bushing-less =
plate affect the ability to use springing effectively?
What is physically taking place in 'springing'? What is happening to =
pin, along how much of its length? to the top of the tuning pin hole or =
the bushing?
What part do characteristics of the tuning pin play in tuning =
characteristics?
a) Tolerance to nominal size
b) Type of steel
c) Method of thread formation
d) Finish (blue, nickle, etc)
Do small and large ply blocks have different tactile tuning =
characteristics if measured at the same static torque?
Relationship of pin maneuverability to friction ratio of front string =
bearing points as a determinant of tunability. What is too little =
friction? too much?
Please remember that you will be marked "incorrect' for any questions =
unanswered. =20
David Skolnik
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