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#3069524 01/15/21 05:46 PM
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There was a question in another thread, so I thought I'd start here with a little background behind the levers.

They have a free motion cam - at the end of the free play, the weight on the lever impacts directly to the tuning pin with less possibility of flag polling. There are a few different designs, but all share those attributes.

Hopefully, most of you will have seen the demonstration (or can try it yourself) where a tuning pin is installed in pinblock material where the bottom of the pin extends out a bit. A hole is drilled in the pin to allow a piece of wire to act as a pointer for the position of the "foot" of the pin. When turned from above with a lever, people are often surprised to see the pointer remain still while the lever can be moved back and forth a bit. That demonstrates the twisting possible within the pin itself. That feeling should be familiar to most techs that have dealt with a tight pin block - that perception of the lever and the pitch moving without feeling the foot of the pin shift.

The impact lever avoids this because the impact is short enough to either move the entire pin, or not move it at all. With slight taps, it is possible to move the pin (and pitch) in tiny increments. Of course, there are situations that render the impact lever uncontrollable. That's one of the reasons I carry 4 different levers to deal with all sorts of potential piano tuning problems.

Another situation where I've found impact levers a big help is with excess string friction. Instead of trying to manage the non-speaking length tensions to "bleed" across the points of high friction, an impact lever often helps segments move together across friction points - releasing the friction with the quick motion.

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Where can I see a video of that demonstrated? I've tried putting a long tuning pin in a vice, and a few other ways of testing, and I have never been able to induce any twist in a pin, where the foot didn't move with the head. If you put the foot in a vice, there is zero movement. The hammer doesn't budge.

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Originally Posted by piano411
Where can I see a video of that demonstrated? I've tried putting a long tuning pin in a vice, and a few other ways of testing, and I have never been able to induce any twist in a pin, where the foot didn't move with the head. If you put the foot in a vice, there is zero movement. The hammer doesn't budge.

If seen youtube videos of a exactly this - a big pointer on the bottom that doesn't move in sync with the tuning hammer.

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Originally Posted by piano411
Where can I see a video of that demonstrated? I've tried putting a long tuning pin in a vice, and a few other ways of testing, and I have never been able to induce any twist in a pin, where the foot didn't move with the head. If you put the foot in a vice, there is zero movement. The hammer doesn't budge.
This is the one I watched when I was trying to figure out what these were: https://youtu.be/TZrqeCfj5i4


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Originally Posted by pyropaul
If seen youtube videos of a exactly this - a big pointer on the bottom that doesn't move in sync with the tuning hammer.
You've seen a video of that? Where? I've searched, I can't find anything. Neither have I seen anything like that in person. I've also never been able to recreate any situation where I could put any kind of notable twist in the pin. People makes these claims all the time, but I have NEVER seen anyone provide evidence, or a means of testing out such a hypothesis. If such a demo is available, I really want to see it with my own eyes. Because all the testing that I have ever done indicates that such a claim is impossible. Maybe there is a problem with my methodology. The scientific methods requires that other people be able to recreate a situation where the head of the pin twists(moves) and the foot doesn't. That is a bold claim that deserves some backing up. I've tried to twist a pin in so many different ways, but so far, I haven't been able to get any twist to happen.

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SonatainfSharp, thank you for the video. But, I am looking for evidence that it is possible for the tuning pin itself to twist.

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Originally Posted by piano411
Originally Posted by pyropaul
If seen youtube videos of a exactly this - a big pointer on the bottom that doesn't move in sync with the tuning hammer.
You've seen a video of that? Where? I've searched, I can't find anything. Neither have I seen anything like that in person. I've also never been able to recreate any situation where I could put any kind of notable twist in the pin. People makes these claims all the time, but I have NEVER seen anyone provide evidence, or a means of testing out such a hypothesis. If such a demo is available, I really want to see it with my own eyes. Because all the testing that I have ever done indicates that such a claim is impossible. Maybe there is a problem with my methodology. The scientific methods requires that other people be able to recreate a situation where the head of the pin twists(moves) and the foot doesn't. That is a bold claim that deserves some backing up. I've tried to twist a pin in so many different ways, but so far, I haven't been able to get any twist to happen.
piano411,Your words is right, golden words. I'm think that anything speculation "twist pin" about, it's simple words. A pin has very hard material and it's don't twist NEVER,

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Originally Posted by Maximillyan
A pin has very hard material and it's don't twist NEVER,
Right. It is simple observational science we are talking about. I think most tuners have access to a vice. Right? If you simply put the foot of a tuning pin in there, and then try to turn the head of the pin with your normal tuning hammer, that thing is not going anywhere! Literally, that material does not twist under the loads we generate. I'm sure some engineers can put some real number on what it would take for that to twist, but it doesn't really matter, the forces required are not within our range of function.

RonTuner makes it sound like this demo is at least somewhat common. And, pyropaul seems to indicate that there have been multiple videos out there. I don't know what they have seen, if they have seen anything at all, but I am sure there is an alternate explanation. Tuning pins flagpole all the time, or it could be the fit of the tuning hammer.

I don't know, but I really want to see something. People try to use this all the time for the basis of their tuning technique. Bad science leads to bad technique. If I am in any way wrong about this twist, then I really need to know now to adjust my tuning approach.

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Well, I certainly can feel the pin twist before it breaks free, and I have no idea what other explanation can be given for the change in pitch, (up and then down) when applying CW torque with the tuning lever and then releasing it especially when any flapoling force would tend to do the opposite (lever at 3 o'clock on an upright).

Found a torsion shaft calculator online and using some numbers I thought were in the ballpark came up with 1 & 1/2 degrees of twist at 100 inch pounds:

https://amesweb.info/Torsion/torsion-of-shaft-calculator.aspx

But it does seem odd that it is hard to find a video demo. Maybe because it seems so obvious. I might try to work something up.


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Originally Posted by SonatainfSharp
Originally Posted by piano411
Where can I see a video of that demonstrated? I've tried putting a long tuning pin in a vice, and a few other ways of testing, and I have never been able to induce any twist in a pin, where the foot didn't move with the head. If you put the foot in a vice, there is zero movement. The hammer doesn't budge.
This is the one I watched when I was trying to figure out what these were: https://youtu.be/TZrqeCfj5i4
Well I just watched that whole video and no evidence of twisting pins there at all.
I'd be most interested to see the video about the drilled hole and pointer.
Over my lifetime I've seen the change to chromed pins (from blue).
I am convinced that I cannot control a chromed pin (or stainless) as accurately as a blue one.
Am I imagining it or is it possible that one is more "twistable" than the other?
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Perhaps the ‘twisting’ being referred to is something that feels like twisting, but not actual twisting? Obviously one can’t actually feel the bottom of a pin not turning while turning the top through a 10”+ lever, so whatever they’re feeling would be an indirect sensation, and it could be something else. Just a thought...

Whatever the case, I had an impact lever and used it sometimes early on after I learned to tune. After I got used to it and could use it well that ended up altering my technique with a regular hammer. I can’t really describe exactly what I do, but I also hold a regular hammer right up near the head. Not sure if it’s related, but I’ve had good tuning stability smile

I haven’t used the impact lever for many years, but I was glad I bought it since it has an actual Hale head which I moved to another newer hammer I bought since it had a slightly lesser quality head.

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Originally Posted by N W
Originally Posted by SonatainfSharp
Originally Posted by piano411
Where can I see a video of that demonstrated? I've tried putting a long tuning pin in a vice, and a few other ways of testing, and I have never been able to induce any twist in a pin, where the foot didn't move with the head. If you put the foot in a vice, there is zero movement. The hammer doesn't budge.
This is the one I watched when I was trying to figure out what these were: https://youtu.be/TZrqeCfj5i4
Well I just watched that whole video and no evidence of twisting pins there at all.
I'd be most interested to see the video about the drilled hole and pointer.
Over my lifetime I've seen the change to chromed pins (from blue).
I am convinced that I cannot control a chromed pin (or stainless) as accurately as a blue one.
Am I imagining it or is it possible that one is more "twistable" than the other?
Nick
can't say anything for the chrome pin. In the USSR, galvanized pins were used. In particular, the piano "BELARUS" 71-72 years. These pianos have been a lost tuning pin after only 2-3 years of use. Some Russian tuners are of the opinion that such a coating of the tuning pins was the formation of dry zinc grease and, as a result of the complete loss of friction of the pinblock hole from with the tuning pins,

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I saw the demonstration during two different PTG conventions decades ago. Even went up and tried it myself at the end of class. The movement wasn't a lot, so that 1 to 1 1/2 degrees is probably right.

I tuned a re-pinned troublesome piano yesterday that was tightly pinned where I could definitely feel the top of the pin move without the foot moving in the block. (I could hear the pitch shift at least 10 cents without ever feeling the little 'tick' of movement down below.) I used a rigid carbon-fiber lever so got excellent feedback from the actual movement of the pin. Near impossible with any traditional lever technique, but I got through 'just ok' with the impact lever.


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Originally Posted by UnrightTooner
Well, I certainly can feel the pin twist before it breaks free, and I have no idea what other explanation can be given for the change in pitch, (up and then down) when applying CW torque with the tuning lever and then releasing it especially when any flapoling force would tend to do the opposite (lever at 3 o'clock on an upright).

Found a torsion shaft calculator online and using some numbers I thought were in the ballpark came up with 1 & 1/2 degrees of twist at 100 inch pounds:

https://amesweb.info/Torsion/torsion-of-shaft-calculator.aspx

But it does seem odd that it is hard to find a video demo. Maybe because it seems so obvious. I might try to work something up.

If I recall correctly, the video was from (banned for quite a while now member) Mark Cerisano. Steel is an elastic material and of course will twist - the question is how much it will twist before the static friction of the hole is overcome, but the twist will certainly be non-zero before that is overcome. The bigger question (and one that Mark was trying to address) was how to ensure that any residual twist from the initial torsion before overcoming the friction could be addressed. One could envision a twisted pin locking into place and having insufficient stored torsion to overcome the static friction of the new position. But to say it's impossible is to deny basic materials science and physics.

[edit] If you think of torquing a bolt to a specific torsion, that torque that you measure is stored as twist in the bolt. If there was no twist, there would be no torque. A twisted (torqued) bolt stores energy in the same way a spring does.

Paul

Last edited by pyropaul; 01/16/21 11:20 AM. Reason: Added discussion of torqued bolts
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I remember a while ago 411 raised the question of putting a pin in a vice and seeing if it would twist. I think he said it would not. (Sorry, I can't look it up as I have activated the ignore button on his posts)
How about if one painted a perfectly straight white line on a blue pin and filmed it from the side as a tuning hammer was appled. Any twis should show up fairly well?
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Originally Posted by pyropaul
...

[edit] If you think of torquing a bolt to a specific torsion, that torque that you measure is stored as twist in the bolt. If there was no twist, there would be no torque. A twisted (torqued) bolt stores energy in the same way a spring does.

Paul

Well if I think about torqueing a bolt, I think of the resulting force on the "screw" (a spiraled, incline plane, one of the simple machines) multiplying in order to force the pieces together. It actually stretches the bolt a little, more than leaving residual twist.


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I really believe in the impact technique. I bought an impact hammer a while back but discovered it's really hard on your wrist and that's my problem area. I know lots of people have issues with their shoulder and in that case the impact hammer would be great, but for me, my shoulders are fine, so I do the next best thing and use an impact (or jerking) technique with my Fujan that I've extended to 17". But again, I'm a believer in the impact technique!


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Originally Posted by UnrightTooner
Originally Posted by pyropaul
...

[edit] If you think of torquing a bolt to a specific torsion, that torque that you measure is stored as twist in the bolt. If there was no twist, there would be no torque. A twisted (torqued) bolt stores energy in the same way a spring does.

Paul

Well if I think about torqueing a bolt, I think of the resulting force on the "screw" (a spiraled, incline plane, one of the simple machines) multiplying in order to force the pieces together. It actually stretches the bolt a little, more than leaving residual twist.

It's both - if the bolt can stretch it can twist. I $64k question is whether the pin stays twisted or if it gradually untwists (if not left in an untwisted state) - I think this is what Mark Cerisano was banging on about.

Paul.

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I'll try to make a mock up and video in the next week.


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