While the term "set the pin" has been very common for decades (well over a hundred years), the truth of the matter is that it is a false image, with little relationship to reality. The image old time tuners used was that of the pin in a somewhat oblong hole in the pin block (oblong because of the pull of the tension of the wire). When you raised pitch, you lifted the pin in that hole, turned it so that the string rose above the target pitch, then settled or set the pin back into its rest position in the hole, bringing it to pitch. I have read that story in text books at least back to the 1890s. It is hokum, never was actually true, though imagining it to be true probably helped new tuners learn how to get a somewhat stable tuning, as a starting point.
The facts are these:
The top of the pin itself will twist before the bottom of the pin moves in the pin block. How much depends on how tight the pin is in the block. In a tight block, the top of the pin will twist enough to change pitch by 25¢ and more before the pin actually breaks loose and turns in the block. With a looser fit, that change in pitch before the pin turns can be pretty small.
The pin wil flex (not bend, flex) along its length when the tuning hammer is twisting it. That will occur at a right angle to the lever arm. (This won't occur with a T hammer, or with Dan Levitan's C hammer). This will have the greatest (temporary) effect on pitch when the flex is in line with the string - hammer at 3 or 9 o'clock. The effect will be minimized when the tuning hammer is in line with the string (12 o'clock).
There is friction between the speaking length of the string and the tuning pin. This varies from piano to piano, and from string to string, depending on materials (brass, cast iron, felt), conditions (rust or lack thereof, lubricant).
Pin twist and flex are temporary. As soon as you stop applying force to the tuning pin with your tuning hammer, the pin will revert to its original shape. (If this were not so, tuning pins would change shape over time, which does not occur.) To be precise, the pin is always being twisted and pulled by the string, so its "rest position" includes some force being applied to it. But the effect of the hammer on the pin, both twisting and flexing will disappear as soon as you stop applying force to the tuning hammer.
If you'd like to verify that, there is a simple jig that can be made. A scrap of pin block material in a vise. Drill a hole, pound in a tuning pin. Drill a hole in the bottom of the tuning pin to accept a piece of wire. Epoxy a wire into that hole and bend it so that it is in line with the surface of the pin block. Glue another wire into the becket hole. Bend those wires so that they meet about a foot away from the tuning pin (put a right angle bend in the end of each and bring the ends to the two wires together so they touch.
Now turn the tuning pin. You will see that the top wire (from the becket) moves away from the bottom wire, by maybe 3/8" (depending how tight the hole is) before the bottom wire moves. You will also see that when you release the hammer, the wire ends "magically" go right back into line with one another. No lag in time. No need to "set the pin" to make it happen. Flex is smaller than twist, so harder to measure, but it behaves precisely the same.
Yes, you can bend a pin, meaning that you apply so much force that it yields and is permanently deformed. That takes a lot of force. It really isn't an issue for anyone using any delicacy at all in the process of tuning.
The problem of creating a stable tuning comes down to allowing for twist, flex, and friction, and developing the ability to make extraordinarily minute rotational adjustments to the tuning pin. This is the actual skill of tuning. Unless you develop it, all the high-falutin tests and beat rates and magical tuning styles mean absolutely nothing. Friction is the real culprit when it comes to instability: you can get the impression the string is in tune, because it stays for the time being. It can even stay following hard blows and not actually be stable. So how are you to know when a string/tuning pin is in a stable state?
That much is a teaser. Back in 2014, there was a long discussion on tuning hammer technique, in which David Love and I were the principal participants. I decided to gather it together in a blog, which you can read
here. It is long, involved, and probably confusing, but I think if you can read it and digest it, it may be helpful in answering that very basic question, which should be worded "How do I achieve a stable tuning?"
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Fred Sturm
University of New Mexico
fssturm@unm.eduhttp://fredsturm.nethttp://www.artoftuning.com"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
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Original Message:
Sent: 08-11-2017 12:06
From: Justin Hill
Subject: Setting the pin
Here's another topic of discussion, plus I'm not sure exactly who to listen to with what advice I've gotten.
How do you set the pin and make it as stable as possible til the 6 month tuning again? This is what I'm up against now, and I am dreading once I actually start the business that customers will call a couple months or weeks later saying their piano is out of tune and I'll lose money having to go back and retune again.
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Justin Hill
Jacksonville IL
217-370-2458
tuneworkspianoservice@gmail.com
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