[CAUT] Tuning Pin Questions

[Fred Sturm]

On Jul 7, 2008, at 2:58 PM, Kendall Ross Bean wrote:
>
>
> I would love to see a discussion by parties hopefully much more  
> knowledgeable than myself, about why these silly pins are the way  
> they are today.
>

Hi Kendall,
	I don't know how knowledgeable I am on this subject, but I think the  
answer to most of your questions can be probably summarized in two  
words: aesthetics and salesmanship. A similar example is key bushing  
cloth, which we all "know" should be white inside. Maybe at some point  
there was a reason (eg, the dye didn't penetrate during the processing  
- only when the felt was of sufficient density), but now they go to  
some trouble to meet the expectation. It is starting to change:  
Steinway now has white key bushing cloth (very recent - probably EU  
green regulations or PR, as it initiated in Hamburg). I think the hype  
about "bluing" is very similar, and done to try to sell more pins to  
gullible technicians. That's my own skeptical opinion, based on what  
experience I have. But maybe someone else with more varied experience  
can tell us why one kind of bluing is better than another, and why  
bluing is better than its absence.
	I think that the real difference in tuning pins (available stock -  
all being strong enough to stand the torque of being turned while  
tuning) is manufacturing tolerances. Are they round within .001"? Are  
all the pins in a set within .001" of one another? If so, you've got a  
good set. The pinblock will make much more difference: material?  
number and direction of plies? glue? drill bit used? control of  
drilling speed? to name some of many of the factors that go into  
determining if pins hold well and turn well.
	Threads are for pin removal. They also add to the surface area, so  
they impact the friction with the block. Smooth pins work okay in  
harpsichords. I don't know if the extra torque of pianos would change  
that. But I wouldn't want to experiment, since I want the pins to be  
removable. "Reverse thread" is generally accepted as hogwash salesman  
claim. It is probably a side-effect of the method of cutting threads,  
where some filings are laid down with a direction. I don't think it  
actually wears out a block, though I can see where that opinion would  
come from. I think the amount of cutting done in a tuning pin hole  
would be limited rapidly by being clogged by wood fiber. In any case,  
I don't think pianos with such pins have a unique behavior I can  
identify, though really one would have to follow a piano through a  
period of years to come to a conclusion, and I haven't done that (not  
with conscious intent, knowing what I had to begin with and observing  
to see what happened over time).
	Tapered is, I think, a vestige of times when blocks were solid, and  
drilling tolerances not that tight. To work really well, you need  
tapered drill bits to drill holes with the same taper as the pin. The  
experience I have with tapered pins is in harpsichords. A lot of them,  
the pins aren't truly tapered, they are cylindrical to the bottom  
couple centimeters, then that lowest portion is tapered pretty  
acutely. Not a very good design in my experience. They are often hard  
to remove, and don't really get much tighter driving them in further.  
I have only very limited experience with truly tapered pins, and I  
don't know if the holes were drilled tapered. In any case, I don't the  
the possible gains outweigh the extra expense.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu




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