Tuning Pin Size

[larudee@pacbell.net]

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Good point.  There is a slightly greater danger of this than there would
be with ordinary pins.  The larger the size difference between the two
portions, the greater the risk.  However, if the pin is that tight, it
won't be tunable anyway.  On the other hand, I don't think I would
advise a 6.75mm. top on a size 5/0 (7.45mm.) base.  I may be
overcautious, but I wouldn't go over a half millimeter difference in
diameter (= 1/4 mm. radius).  I haven't done the math on the stress
factors.

Paul

David Love wrote:

> Paul: Because of the difference in diameter between the coil portion
> and the block portion, is there any danger of shearing the pin off if
> the pin is too tight in the block? David Love
>
>      ----- Original Message -----
>      From: larudee@pacbell.net
>      To: pianotech@ptg.org
>      Sent: January 26, 2002 11:54 AM
>      Subject: Re: Tuning Pin Size
>       David,
>
>      You are right on target.  Comments below.
>
>      Paul
>
>      David Skolnik wrote:
>
>     >  Paul -
>     > I think you are right.  There has and will be plenty to
>     > discuss.  I, at least, have already gotten the Feb issue,
>     > and also promise to read it, but some of my concerns date
>     > back to a number of months ago when, in response to a
>     > particular thread, you first started talking about your
>     > pin.  One of these concerns is that, as a way of avoiding
>     > block replacement, they are not viable if, as in many of
>     > the pianos I see, the original pins are already against
>     > the plate, whatever their size.
>
>      Yep, there's no way my pins will back the holes off away
>      from the plate.  The only good solution there is a new
>      block.
>
>     > Second, while I understand (I think) the theory regarding
>     > torque and flex, I suspect that other factors, such as
>     > lack of quality control of pins, or of the fit between pin
>     > and block (whether new or repinned), not to mention too
>     > much or too little friction between pin and sounding
>     > length of string, have much effect upon tunability than
>     > the diameter around which the string coils.
>
>      These are all extremely important, and there is no way that
>      my pins are designed to compensate for inadequacies in any
>      of these areas.  In fact, one of the cautions I include with
>      the pins is not to overtighten them, which is a problem I
>      find with some restrung pianos.  My pins do not need to be
>      as tight, because of the reduced torque.  Furthermore, the
>      difference between what I call uptorque and downtorque
>      (pulling with or against tension) is less with my pins than
>      with other oversize pins.  Another point is that the design
>      of my pins frees the diameter at the coils to be essentially
>      independent of the diameter in the rest of the pin.  Of
>      course there are limitations of strength, but otherwise very
>      narrow diameters like 6.75mm. are entirely feasible on a
>      base that is as big as you want.  That's the principle that
>      I think would be of use to Steinway.  Finally, Klinke, the
>      manufacturer of my pins and regular Diamond pins makes just
>      about the most precise ones in the business.  I needed that
>      kind of precision for my pins in order to get them perfectly
>      coaxial and cylindrical.  Mic them all you want; they come
>      out virtually identical.
>
>     >  Remember two things about pin flex...1) It can be a very
>     > useful tool in fine tuning, and 2) it is affected by
>     > tightness in the block.   A tight pin with no flex can be
>     > as difficult to fine tune as a pin with too much flex,
>     > whatever its diameter.
>
>      Yes, flex can be useful, and some manufacturers rely on it
>      more than others in their design.  I like to minimize it as
>      much as possible because it compromises the pin's function
>      as a stable anchor, and I prefer to achieve tunability by
>      other means, to the extent possible.
>
>     >
>     >
>     > Now to read your article and find out what you really
>     > said..
>     >
>     >
>     > David Skolnik
>     >
>     > At 11:37 PM 01/25/2002 -0800, you wrote:
>     >
>     > > Chances are that at this point we get into "but what
>     > > about...," in which case I get to rewrite the whole
>     > > article on line.  I would just as soon wait for the
>     > > February Journal.  There will probably still be plenty to
>     > > debate, but at least not the stuff I've already covered
>     > > in the article.
>     > >
>     > > Best regards,
>     > >
>     > > Paul
>     >

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