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#2180153 - 11/10/13 03:28 PM Re: Tuning Stabilty [Re: Mark Cerisano, RPT]
Mark Cerisano, RPT Online   content
1000 Post Club Member

Registered: 01/24/10
Posts: 1204
Loc: Montreal, Quebec, Canada
A teacher who is not ready to learn, is not ready to teach.
_________________________
Mark Cerisano, RPT
www.howtotunepianos.com

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#2180172 - 11/10/13 04:16 PM Re: Tuning Stabilty [Re: Withindale]
DoelKees Offline
1000 Post Club Member

Registered: 05/01/10
Posts: 1707
Loc: Vancouver, Canada
Originally Posted By: Withindale
Originally Posted By: Mark Cerisano, RPT

2. Your model Kees, while interesting, does not consider the bending motion. This is critical if your model is to help tuners visualize a way to produce stability. For that reason, it should really imagine situations where certain hammer angles, combined with certain elastic deformation, result in a Non-Speaking Length tension centered within the Tension Band.

Mark,

I am not so sure it would be of much practical use for Kees to elaborate the model, but why not?

The main reason not is that modeling the pin bending required knowledge of more material parameters which are not directly measurable, and I don't know how to determine them.

So for now the simulation is limited to tuning with the lever parallel to the string and no flagpoleing.

If I get time to revisit this project I will see if flagpoeling can also be modeled.

Kees

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#2180482 - 11/11/13 05:38 AM Re: Tuning Stabilty [Re: James Carney]
Mark Cerisano, RPT Online   content
1000 Post Club Member

Registered: 01/24/10
Posts: 1204
Loc: Montreal, Quebec, Canada
Originally Posted By: James Carney

The C-lever is all-steel with zero flex, so all of the energy is being transferred to the pin; nothing lost like there is with a traditional wooden handle.

But it's that combined with the placement of your hand - in line with where the pin is in the block - that separates this tool from the other "no flex" tuning levers. Additionally, your torso and upper arms become part of the movement of the pin - I think proponents of Alexander technique would agree that it is ergonomically brilliant.

Once I get the pin rotated to where I want it, I can manipulate the C-lever in the tiniest of increments to remove any residual twist, and if I need to I can use controlled flagpoling to find the ultimate placement. But what's amazing is I didn't have to think about it at all after a while - the tool does most of the work for you. I think it removes the residual twist much more efficiently than traditional levers do. That's why my clean-up passes take so little time. There are far fewer strings to correct after a full tuning. (I always tune unisons as I go, whether aural or ETD.)


Hi again James,

I respect your passion for the C lever, and I don't want to appear arrogant, claiming to know stuff I have no experience with, so I imagine you don't either.

Traditional hammers are made of steel as well and have a shorter moment arm, so all else considered equal, would have less deflection.

I can also remove any residual twist. I also tune with my whole body. I also use controlled flagpoling with simple massaging parallel to the pin. I also don't think about the physics of what I am doing; it is natural now to me. Twist is applied in a rotational vector to the pin tip; the two hammers are identical in this application; except that the moment arm is longer for the C lever.

Yes I know I haven't tried it, but I doubt someone's tunings are better just because of it, all else equal. I hope that isn't what you are saying.

Best Regards,
_________________________
Mark Cerisano, RPT
www.howtotunepianos.com

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#2180501 - 11/11/13 07:29 AM Re: Tuning Stabilty [Re: Mark Cerisano, RPT]
Mark R. Offline
1000 Post Club Member

Registered: 07/31/09
Posts: 1968
Loc: Pretoria, South Africa
Originally Posted By: Mark Cerisano, RPT
Twist is applied in a rotational vector to the pin tip; the two hammers are identical in this application; except that the moment arm is longer for the C lever.


Of course, both hammers apply twist. The point is that on a traditional hammer (all the more pronounced in a 10 or 15° head), the hand exerts a force on the lever at a point or plane above the pinblock. Hence, a traditional lever also applies a lateral bending force (flagpoling) which must be compensated, e.g. by
... using the thumb as a fulcrum, or
... using a "motorcycle throttle" grip, or
... "after-tuning", allowing the flagpoled pin to spring back.

On the C-lever, the hand exerts its force on the lever in the plane of the pinblock, resulting in purely rotational force (twist, torque) on the pin. The C-lever can deliver twisting and bending movements completely independently.

No, I don't own a C-lever (never will), but when I first saw Dan Levitan's video, I actually did a few simple experiments with wire, to observe the bending forces, depending on where the force was applied. Quite an eye-opener.
_________________________
Autodidact interested in piano technology.

1922 49" Zimmermann, project piano.
1970 44" Ibach, daily music maker.

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#2180523 - 11/11/13 08:47 AM Re: Tuning Stabilty [Re: Mark R.]
jim ialeggio Offline
500 Post Club Member

Registered: 06/03/05
Posts: 621
Loc: shirley, MA
Originally Posted By: Mark R.
On the C-lever, the hand exerts its force on the lever in the plane of the pinblock, resulting in purely rotational force (twist, torque) on the pin. The C-lever can deliver twisting and bending movements completely independently.


This is correct, and as someone who uses this lever, the simplification of the rotation is quite an eye opener. I continue to be impressed with how little NSL pitch change can be induced even in tight blocks...if one chooses. Pin bending is a choice, not an inevitability.

There are a number of fine techs, David Love and Fred Strum come to mind, who have developed their own lever techniques to do what this C lever does for you. They analyze the pin torque/NSL conditions, then choose an appropriate lever angle and flex the pin in a direction that counters NSL induced pitch change...coming right up to pitch without guessing where the pitch will settle in the After Tuning.

Mark, Pianotek sells these with a 30day try-it-and-see return policy. As you are a teacher, and a teacher who has an excellent knack for breaking a complex task down into its component parts, this lever could be very useful as a teaching tool, as it can clearly demonstrates the forces you have explained previously.

With that, though, I'll hold further comments for James C's Levitan C lever thread.

Jim Ialeggio
_________________________
Jim Ialeggio
www.grandpianosolutions.com
advanced soundboard and action redesigns
978 425-9026
Shirley Center, MA

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#2180926 - 11/12/13 08:12 AM Re: Tuning Stabilty [Re: Mark R.]
Roy123 Offline
1000 Post Club Member

Registered: 09/20/04
Posts: 1708
Loc: Massachusetts
Originally Posted By: Mark R.


On the C-lever, the hand exerts its force on the lever in the plane of the pinblock, resulting in purely rotational force (twist, torque) on the pin.


That's not entirely true. A sideways force is applied to the pin that is equal to the force applied to the handle of the lever. This statement assumes that the tuner is applying a unidirectional force to the lever, and not a twist. Given the lever's usage, that's pretty much a given. The longer the lever the less this force is, because for a given amount of torque, force is the reciprocal of the lever arm. The C lever is helpful in this regard because its lever arm is longer than most conventional levers.

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#2180944 - 11/12/13 08:45 AM Re: Tuning Stabilty [Re: Mark Cerisano, RPT]
jim ialeggio Offline
500 Post Club Member

Registered: 06/03/05
Posts: 621
Loc: shirley, MA
Interesting...I suspected some force of this nature being applied.

However, practically speaking, because of the way the C lever is oriented on the pin, ie in-line with or close to in-line with the string, whatever sidewise force there is, is applied in a direction that has very minimal, unto undetectable (to me) effect on the NSL induced pitch change. It allows one to entirely eliminate, in a practical way, the bending portion of NSL pitch change...thus eliminating it from the list of NSL effects to be decoded and compensated for.

Jim Ialeggio
_________________________
Jim Ialeggio
www.grandpianosolutions.com
advanced soundboard and action redesigns
978 425-9026
Shirley Center, MA

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#2180958 - 11/12/13 09:31 AM Re: Tuning Stabilty [Re: Roy123]
Mark R. Offline
1000 Post Club Member

Registered: 07/31/09
Posts: 1968
Loc: Pretoria, South Africa
Originally Posted By: Roy123
Originally Posted By: Mark R.


On the C-lever, the hand exerts its force on the lever in the plane of the pinblock, resulting in purely rotational force (twist, torque) on the pin.


That's not entirely true. A sideways force is applied to the pin that is equal to the force applied to the handle of the lever. This statement assumes that the tuner is applying a unidirectional force to the lever, and not a twist. Given the lever's usage, that's pretty much a given. The longer the lever the less this force is, because for a given amount of torque, force is the reciprocal of the lever arm. The C lever is helpful in this regard because its lever arm is longer than most conventional levers.



I hear what you're saying. A very short lever would have to exert a very high sideways force to achieve the same torque.

But I think the point about the C-lever remains the same: it's not so much the size of this lateral force that matters, but the height (relative to the pinblock) at which it is applied.

Although the sideways force of which you speak, does exist, it is effective on the pin at the same height at which it is applied to the lever. Hence, with the C-lever, this sideways force is effectively applied to the pin within the pinblock, eliminating flagpoling. In fact, if the handle of the C-lever were even longer, so that the tuner could apply force at the level of the keys, the pin would flagpole in the opposite direction (because the sideways force is effectively applied below the pinblock). When pushing the lever left, to raise pitch, the pin would actually flagpole to the right. Conversely, if you operate the C-lever at the very top end of its handle, it would operate much like a conventional lever, and flagpole the pin left.

But by operating the C-lever in the middle of the handle, the force is applied at the height of the pinblock, without resulting in any flagpoling.

That's my best understanding of the vectors at play. (Open to correction, gladly.)
_________________________
Autodidact interested in piano technology.

1922 49" Zimmermann, project piano.
1970 44" Ibach, daily music maker.

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#2180969 - 11/12/13 09:52 AM Re: Tuning Stabilty [Re: Mark Cerisano, RPT]
jim ialeggio Offline
500 Post Club Member

Registered: 06/03/05
Posts: 621
Loc: shirley, MA
Hey guys...could we move this to James Carney's C lever thread

Levitan C Lever

I took the liberty of re-posting the last couple of posts on C lever force vectors to the C lever thread


Edited by jim ialeggio (11/12/13 10:14 AM)
_________________________
Jim Ialeggio
www.grandpianosolutions.com
advanced soundboard and action redesigns
978 425-9026
Shirley Center, MA

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#2182196 - 11/14/13 09:27 AM Re: Tuning Stabilty [Re: Olek]
Mark Cerisano, RPT Online   content
1000 Post Club Member

Registered: 01/24/10
Posts: 1204
Loc: Montreal, Quebec, Canada
Originally Posted By: Olek

Marc with all due respect, that is what I do not get with your descriptions, you have no idea of the perceptions I experiment, or you would be using other terms.

You seem to describe it but the way you talk of it make me think you are not experimenting the wanted sensations.

That energy reserve created by putting the pin and pinblock under stress a little more than what is yet there due to the string tension, is where the strenght of tone and longevity of the tuning is, for the part we can manipulate.

I am surprised that, as an engineer you correctly describe friction and static forces for 2 parts of the system, and you leave the 3d out of the equation.




Hi Isaac,

For sure, I am posting on pianoworld to be challenged, for that is the only way to improve one's understanding and move closer to confidence. A teacher must teach within a very high reserve of confidence. (And it is better if it is not artificial, although that can work too. ;-)

I have read with interest, your much referenced concept of "stored energy within the pin" and I have agreed with your concept of concert tuning stability.

What I was having trouble with was our inability to see eye to eye. I have thought a lot about it, trying to figure out what it is you were getting at. I think I may have figured it out; we may be talking about the exact same thing, just using different terminolgy and focusing on different parts of the system where each part produces the same result.

I have created a new thread about it called "Concert Tuning Stability". Let me know what you think.

http://www.pianoworld.com/forum/ubbthreads.php/topics/2182195.html#Post2182195
_________________________
Mark Cerisano, RPT
www.howtotunepianos.com

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