Pianotech

A recent discussion got me curious to pull out an old experiment... I drove several tuning pins into a scrap piece of pinblock to see how much flexing/flagpoling force it would take to actually bend over of them permanently, and what "gave" first. It's not shown in the photos but I'm just putting an old tuning lever on them and pushing downward with increasing force until it bends permanently.

From what I've seen:

• The pin always yields at the becket hole
• It takes a fairly stupid amount of force to get this to happen. You have to push way harder than you ever would for tuning purposes.
• If I keep going it eventually breaks off at the becket hole
• I was unable to permanently bend the pin below the becket hole. You can see this in the pictures with the ruler. I also took one out, sawed it off at the becket hole, dressed the edges, and rolled it on a flat surface to check that it really was still straight. (You can see that in the video, even though the focus is not great for much of it).
• I thought I could get a permanent deformation away from straight in the lower part of the pin by driving one in with the pin pinch held well off vertical, but this actually didn't work. I couldn't get it to deform permanently at all. Perhaps it's because my vice setup has too much give compared to a real piano.

I've always suspected that the few bent pins I've run into were bent during the stringing process.

A recent discussion got me curious to pull out an old experiment... I drove several tuning pins into a scrap piece of pinblock to see how much flexing/flagpoling force it would take to actually bend over of them permanently, and what "gave" first. It's not shown in the photos but I'm just putting an old tuning lever on them and pushing downward with increasing force until it bends permanently.

From what I've seen:

• The pin always yields at the becket hole
• It takes a fairly stupid amount of force to get this to happen. You have to push way harder than you ever would for tuning purposes.
• If I keep going it eventually breaks off at the becket hole
• I was unable to permanently bend the pin below the becket hole. You can see this in the pictures with the ruler. I also took one out, sawed it off at the becket hole, dressed the edges, and rolled it on a flat surface to check that it really was still straight. (You can see that in the video, even though the focus is not great for much of it).
• I thought I could get a permanent deformation away from straight in the lower part of the pin by driving one in with the pin pinch held well off vertical, but this actually didn't work. I couldn't get it to deform permanently at all. Perhaps it's because my vice setup has too much give compared to a real piano.

That's what I assumed as well, probably because somebody told me.

I suppose one variable is the type of pin. This one was a spare I had lying around but I *think* it was a Klinke 2/0. Maybe they're harder to bend than some others.

I've always suspected that the few bent pins I've run into were bent during the stringing process.

A recent discussion got me curious to pull out an old experiment... I drove several tuning pins into a scrap piece of pinblock to see how much flexing/flagpoling force it would take to actually bend over of them permanently, and what "gave" first. It's not shown in the photos but I'm just putting an old tuning lever on them and pushing downward with increasing force until it bends permanently.

From what I've seen:

• The pin always yields at the becket hole
• It takes a fairly stupid amount of force to get this to happen. You have to push way harder than you ever would for tuning purposes.
• If I keep going it eventually breaks off at the becket hole
• I was unable to permanently bend the pin below the becket hole. You can see this in the pictures with the ruler. I also took one out, sawed it off at the becket hole, dressed the edges, and rolled it on a flat surface to check that it really was still straight. (You can see that in the video, even though the focus is not great for much of it).
• I thought I could get a permanent deformation away from straight in the lower part of the pin by driving one in with the pin pinch held well off vertical, but this actually didn't work. I couldn't get it to deform permanently at all. Perhaps it's because my vice setup has too much give compared to a real piano.