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Hammer Technique

  • 1.  Hammer Technique

    Posted 04-30-2021 10:47
    I am continuing this discussion started in a different thread on Hearing Damage.

    I just finished tuning a grand which gets delivered tomorrow :-)
    Koval Mild Victorian Temperament per the new owner's request and my recommendation.

    I can't conceive how a Long NSL has a different tension than a Short NSL. It has a different pitch due to its length. Maybe a factor is proportional: tension/length.
    But each reacts to torsion flexing about the same, the shorter being more sensitive. How does one actually measure the tension in a confined string segment?

    The short NSL's were more reactive to pin movement (torsion control) than the longer ones.

    It wasn't until I started using a Counter Bearing Lubricant, that I realized the ability to fine-tune because of the improved ability to read minor torsion flexing and pitch motion.
    Having a Verituner helps to see even the most minute of variations.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------


  • 2.  RE: Hammer Technique

    Posted 04-30-2021 17:29
    Because our job as tuners is to equalize tensions in the SL and NSL's, by definition, the tension in the SL segments, and NSL's, will be equal, or very close to each other. If the tension is not pretty darn close, the SL pitch will not be stable.

    This means tension is a non-negotiable given in all the segments. NSL pitch will be dependent on NSL length * tension * string mass (in this case indicated by diameter).

    I think you are referring actually to elasticity, and not tension. There is elasticity to consider in the various NSL's which have different lengths. The longer the length and the smaller the diameter of the wire, the greater the elasticity.  

    I totally agree about the minute information the ETD (I use Only Pure) affords you when reading fine tuning movements of torsion flex effects on elasticity and tension.  This aspect of an ETD, gets me really stable settings with hammer technique alone. I do not strike the key hard ever...it hurts both my hands and my ears, and makes the whole tuning process a chore.




    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 3.  RE: Hammer Technique

    Posted 04-30-2021 17:39

    I totally agree about the minute information the ETD (I use Only Pure) affords you when reading fine tuning movements of torsion flex effects on elasticity and tension.  This aspect of an ETD, gets me really stable settings with hammer technique alone. I do not strike the key hard ever...it hurts both my hands and my ears, and makes the whole tuning process a chore.
    Jim Ialeggio,  04-30-2021 17:29


    I'll add my hearty agreement to the above. My ear is really good, and I usually like my aural tunings a bit better than most RCT calculations. That being said, I have learned something about hammer technique that would have been hard with only aural tuning. Not impossible, but almost impossible. For this alone, the ETD has been worth it.

    ------------------------------
    John Formsma, RPT
    New Albany MS

    Live not by fear or lies.
    ------------------------------



  • 4.  RE: Hammer Technique

    Posted 05-02-2021 08:05
    Yesterday, I tuned a Bechstein grand with 2.5~3" c/b felt expanses. The application of a counter bearing lubricant made reading pin flex instantaneous,
    almost like it had c/b bars instead. No drag or ratcheting wires.

    Koval Mild Vic (my default temperament) made the piano glow. My custom stretch was the icing on the cake :-)

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 5.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-02-2021 09:30
    I'll add my data obtained from experimentation and measurement.

    We cannot measure NSL tension directly. I've looked into strain gauges. They don't make them small enough. We have to infer tension changes from pitch changes.

    The pitch of the string with the long NSL does not react to pin movements not because of friction, but because of length. Look up Hooke's Law which basically says a long spring of length L doesn't change tension when elongated by a length of x as much as a short spring of length ℓ. In fact, the change in tension of the long spring will be only a fraction of the change in the short spring and that fraction is ℓ / L .

    The pitch of a string with a short NSL is very sensitive to pin movement due to Hooke's Law.

    String segments can never be equal due to friction at the bearing points.

    During hard blows, the speaking length of a string is higher because the string is longer. Think of the string being "stretched" during a hard blow. The shortest distance between two points is a straight line which is what we have when the string is at rest.

    Hard blows do not equalize string segment tensions. Hard blows equalize tensions that exist during the hard blow, which produces the higher speaking length tension. After hard blows, the speaking length tension reduces, v-bar/agraffe friction leaves the NSL tension higher; hard blows actually produce unequal tensions. 

    Hooke's Law says movement at the bridge is minute due to the long speaking length. Move the string at the V-bar and the string will move at the bridge by a fraction. String movement at the lower termination point is not an issue with fine tuning.

    High friction causes NSL to behave like a longer NSL. Low friction causes NSL to behave like a shorter NSL.
    E.g. a long NSL can result in the pin moving and pitch not changing; Long NSL tension are not sensitive to pin movements (Hooke's Law).
    But adding a lubricant lowers friction and now the NSL behaves like a shorter NSL; Short NSL tension are very sensitive to pin movements and the pitch will follow the pin movement more closely. (Hooke's Law).

    This effect is noticeable in other situations like short NSL where the pressure bar is not low enough. Very little friction results in the NSL behaving like an even shorter NSL where every little pin movement is followed by a pitch change resulting in a very difficult string to tune stable.

    Which brings up the important idea that we need friction for stability.

    Every action is followed by a reaction. Every twist of the pin is followed by an untwisting. That's why lowering pitch to target and then adding a little clockwise twist, thinking that will create a higher tensioned NSL may be dangerous and unnecessary. The pin will untwist on its own raising NSL tension. If you twist clockwise too much, the pin will untwist on its own CCW and may leave the NSL too loose.

    Lube is not needed on long NSL of high friction pianos. High friction is good and may be the easiest and fastest string to tune stable, as long as the friction isn't in excess like those of old pianos with rust on the v-bar.
    Just pull it up to target and leave it. The friction ensures a tight NSL. The long NSL ensures the tension stays high. (See video below)

    Tuning a Stable String With a Long NSL.
    FREE CLASS - How to Get Superior Stability!
    YouTube remove preview
    FREE CLASS - How to Get Superior Stability!
    Classes have ended. For more information check out: https://howtotunepianos.com/superior-stability/
    View this on YouTube >


    Hearing small changes in pitch is essential for troubleshooting stability problems. ETDs can help but if you want to get superior results aurally, consider double string unison, DSU, where we tune two strings clean, judge the pitch, and then move one string. Pitch change is detected aurally as little as 0.3 cents.

    Using DSU to tune A4 (Listen at the end where I have an unstable string that keeps going sharp)
    Tuning A4 - Video Submission
    Internationalpianotechniciansschool remove preview
    Tuning A4 - Video Submission
    To pass this unit, you must use an ETD to tune A4 using DSU. Notes:Time limit: 5 minutes.Upload your video to YouTube and send me the link.
    View this on Internationalpianotechniciansschool >




    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 6.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-02-2021 13:12
    I posed a question to the previous thread on Health-Related community, which didn't seem to get a response,  so I'd try here.  
    Regarding the torsional ramifications of torque at both the high and low ends of functional range.  Can you show how both a torque of, say 50-60 inch-pounds vs. 120"lbs. vs 180"lbs could change the model of the effects on the NSL as well as altering actual hammer technique?

    Also, related (and probably a different thread again),  has anyone set up an experiment where the friction of the NSL could be  experimentally controlled, starting perhaps with an adjustable friction bearings in place of agraffe and CB?  That way, you COULD use the pitch of the NSL to calculate its tension, as well as see how the increase in friction changes the response of both NSL and SL.

    As Ron Nossaman would have said to me: "so why don't YOU do it"?

    ------------------------------
    David Skolnik [RPT]
    Hastings-on-Hudson NY
    917-589-2625
    ------------------------------



  • 7.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 04:22

    Increased twisting is a function of pin block tightness. 

    More twisting = more untwisting which affects NSL tension when the hammer force is removed.


    The best way to measure NSL tension is as a function of pitch change after a test blow or the Bend Test. Often people want to complicate experimental procedures but we have to remember why we are interested in this subject - to produce superior stability.

    Pitch change after test
    Sharp = too high NSL tension.
    Flat = too low NSL tension.  

    There is a range of NSL tension that produce no pitch change when the hammer force is removed. This is called the Tension Band. 

    The Tension Band rises and narrows on hard blows requiring the NSL to be left high in the Tension Band for the best stability.

    This model has been proven accurate by all the experimental data I've done. 
     



    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 8.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-03-2021 09:59
    "High friction is good and may be the easiest and fastest string to tune stable, as long as the friction isn't in excess like those of old pianos with rust on the v-bar.
    Just pull it up to target and leave it. The friction ensures a tight NSL. The long NSL ensures the tension stays high."

    Mark, this echos my own experience.


    ------------------------------
    John Pope
    University of Kentucky School of Music
    Lexington, KY
    ------------------------------



  • 9.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-03-2021 00:49
    Jon,
    What lubricant did you use and where did you apply it?

    ------------------------------
    Blaine Hebert
    Duarte CA
    626-795-5170
    ------------------------------



  • 10.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-03-2021 10:32
    "High friction is good and may be the easiest and fastest string to tune stable, as long as the friction isn't in excess like those of old pianos with rust on the v-bar.
    Just pull it up to target and leave it. The friction ensures a tight NSL. The long NSL ensures the tension stays high."


    This has often led me to wonder: in certain pianos, is lubrication of the bearing points actually counterproductive? In a high-friction piano, if I can actually get the pitch where I want it, it tends to stay there. However, is it possible a bit of friction and a bit of lubricant can make things worse? The piano is still difficult to tune, and less stable because the string is more likely to slip?

    ------------------------------
    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
    ------------------------------



  • 11.  RE: Hammer Technique

    Posted 05-03-2021 10:40
    The operant thought being, " if I can actually get the pitch where I want it".  This is the difficulty with high friction pianos...fine tuning is next to impossible. Instead, one gets it reasonably close and calls it good enough. Tuning and "voicing" the unison is next to impossible. So stable is possible but really fine tuning is pretty close to impossible, at least for me.



    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 12.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-03-2021 19:45
    I have found over and over that lubrication of CB with CBL is MOST helpful. I don't leave home without it. All those years I fought friction...I like having immediate response when I move the pins. Even if friction is tolerable, CBL makes my life easier. 

    Pwg

    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 13.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-03-2021 20:22
    You folks are all way smarter than me. That said, Jon Page's CBL has turned some of my most difficult old Kawai and Yamaha grands in recording situations into wonderfully tunable pianos. It even works on old Steinways. I've also discovered that if you use it on the  ends of the wires before you splice a string you get a tighter knot and it stabilizes more quickly.

    ------------------------------
    Karl Roeder
    Pompano Beach FL
    ------------------------------



  • 14.  RE: Hammer Technique

    Posted 05-03-2021 20:50
    This is interesting...I have tried lubricating recalcitrant pianos, and I have to say, I never do it any more.  I found it to be completely ineffective.  I used John's CBL as well as Protek. I have to assume that because of the way I use the lever, with no impacts whatsoever, the lube reacts differently to my smooth gentle  movements, or rather doesn't react at all.  Curious how those of you who find the lube useful manipulate the lever. Are you impact tuners predominantly?

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 15.  RE: Hammer Technique

    Posted 05-03-2021 21:15
    Almost always smooth.

    ------------------------------
    John Formsma, RPT
    New Albany MS

    Live not by fear or lies.
    ------------------------------



  • 16.  RE: Hammer Technique

    Posted 05-03-2021 21:17
    I should say, almost always smooth for grand pianos. For verticals, I use the Reyburn CyberHammer impact lever most of the time.

    ------------------------------
    John Formsma, RPT
    New Albany MS

    Live not by fear or lies.
    ------------------------------



  • 17.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-03-2021 21:22
    I use a combination of smooth, impulse, or impact as the need arises. I also am careful in my "flexing" of pins...sometimes this is all that is required. 

    Pwg

    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 18.  RE: Hammer Technique

    Posted 05-03-2021 21:23
      |   view attached
    The latest formulation (as opposed to the initial formulation that Jim has) has more lube percentage and better assists reading fine torsion adjustments.

    Today, I pitch raised w/ o/p and tuned a Yamaha grand that was 20c flat. CBL made the job effortless. Lower friction meant less pin manipulation to target pitch by not having friction adversely affect pin torsion. A quicker realization of target stability.  I pulled it up 20 cents to an A439 target and tuned it at A439 because it will be going sharp soon to 441 or 442. It is right on the water in an exclusive Country Club (photo attached). 

    On the high angle c/b of Aeolian grands (M&H, Chickering) that allow no finesse, the excessive drag was gone with the application of CBL.

    Karl, great tip! I'll do just that on my next splice.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 19.  RE: Hammer Technique

    Posted 05-03-2021 21:50
    Its very interesting...I wonder how there can be such a discrepancy of experience on this?...at least me, in the singular, being the outlier (as usual)

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 20.  RE: Hammer Technique

    Posted 05-04-2021 07:55
    Jim, maybe it's the 14" handle on you tuning hammer.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 21.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-05-2021 19:45
    I've been skimming the posts in this thread but was finally able to sit down and read them all. This is a very important topic to me and I'd like to share my experience.

    Jim - You're not the only outlier, but I haven't tried lubricating friction points on enough pianos to say for sure that it doesn't work for me all the time. Frankly, because I've had it drilled into me so many times from my start to keep lubricants away from the strings, I'm afraid to try on "good" pianos. I tried it on the very worst rendering piano I tune and it made no difference at all. Perhaps it's because the piano was "that bad". Having said that, I suspect my hammer technique compensates for poor rendering pianos quite well. "Practice makes perfect."

    I'm kind of with Peter, but will say the same thing with many more words. ;-)

    I learned hammer technique mostly on my own and it has evolved into something that seems mostly standard as far as I can tell. I change or mix styles as needed depending on the condition of the pin block, friction, etc. I went through a "banging" phase that lasted a few years. I can honestly say with great confidence that I can create an incredibly stable tuning using hard blows, but I haven't used that method in several years. The advantage to hard blows is that they work. The disadvantage is that they are hard on both the ears and the hands. They obviously distort the sound so you can only use them to settle, not listen, and I've been told they can increase the temperature of the string more quickly than regular blows which can mess with the tuning, but I have not experienced a problem from this.

    We know why hammer technique matters: the pin is a dynamic thing, moving both within itself and within the wood, taking all kinds of bizarre twists and leanings one would thing might not even be possible, but the 2 chapter technical demos with lasers proved it. You can't (typically) just raise or lower the pin to pitch without expecting some rebound in one direction or another.

    We know why hard blows work: The extreme vibration of the string combined with the increase in tension on the speaking length make the point between the speaking lengh & non-speaking length move so the tension on the NSL is the same as the SL during that hard blow. When the SL is quiet, the tension on the NSL remains at that higher tension. When the string is struck, any increase in tension won't pull from the NSL because of the higher tension that was left there. If one were to try to get this situation with lever technique only (which is what I do now), there is a risk of getting the NSL tension too high or too low, so that during a hard blow the pitch could shift either direction.

    My quiet tuning method: Although the hard blow method worked, I needed to find a different way. I experimented with everything I could think of, and I finally realized there wasn't a single method that was best for all pianos (at least for me). I had to tune each differently depending on the pin block, friction, etc. I tune with smooth movements more often than not, but some pianos (or sections of pianos, or individual pins) require more jerky movements. With most pianos, I aim from above, lowering the pitch as I put a small bit of pressure on the lever toward the strings. (Yeah, I know; don't bother me telling me why that's "wrong". I know and I don't care; it works.)  By flexing the pin toward the string, I decrease the tension in the NSL enough to help it across bearing points. When the string is at pitch, I release the pressure and the pin flexing back to position puts extra tension on the NSL. How do I know how much? That's a practice thing; it took me a few months to get consistent with it on different pianos. On some occasions, jerky movements work better. Most of the time this is with tighter pins, but not all the time. How do I know? It's the practice thing again. I can't explain it; you just get a feel for it. On an extremely rare occasion, I have used a method demonstrated at a convention on a vertical: You put tension toward the strings as you pull up. When it just starts to hint at going above pitch, you let go. The natural reverse-unwind of the pin drops the pitch from the slightly over pitch position, but the return flex of the pin puts slightly more tension in the NSL. I've never been able to use this effectively on most pianos, but there were two, both Kawais, with "spongy" pin blocks and this method nailed them. Aside from these "methods", I vary from things in between, more or less, and off the wall depending on what works with any given piano on any given day.

    I appreciate this discussion. I'm finding it difficult to teach hammer technique and the more information I find, the better. I'm also finding that teaching hammer technique is much like using it on pianos: Each student, like each piano, is different and I must communicate details to them differently depending on their individual needs, learning style, physical coordination, and thought processes.

    Thank you!
    Maggie

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 22.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-05-2021 21:23
    I was thinking of editing my post but decided to add a "PS"; that's typical of me, anyway. ;-)

    Just thinking about being told that flexing the pin is bad because it reams out the top part of the wood in the block, so is a primary cause of loose pins because the top part of the wood is what grabs the pin. I believe this is incorrect for 2 reasons: 1) I have tuned pianos with very loose pins, completely letting go, and I was literally the second tuner to ever tune the piano, the first being when it was new, 20-30 years earlier. 2) If the top part of the pin is what held the pin, then hammering them in wouldn't cause them to hold.

    I don't flex the pin much, but I do flex it. So far, I have not had a piano with tight pins become loose under my care. We'll see if this happens in the future.

    Just an extra 2 cents. ;-)

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 23.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-05-2021 21:56
    Two points:

    1. Flexing the pin does not cause loose pins
    2. All pins get flexed whether you like it or not.

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 24.  RE: Hammer Technique

    Posted 05-05-2021 22:19
    Just to emphasize David's post:

    <1Flexing the pin does not cause loose pins
    <2. All pins get flexed whether you like it or not.

    The notion that any traditional lever does not flex the pin is just mechanically incorrect, and physically impossible. However, nonetheless, it is taught universally as gospel truth. It is one of those massive bits of misinformation that slows down learners big time, and leaves them grasping hopelessly to understand the behavior of the stabilizing system. The notion that we can somehow avoid bending the pin, with a traditional lever, simply does not reflect the reality of the system.

    Understand how the lever flexes the pin automatically, and unavoidably, and you have a  seriously useful tool to both understand how you are distorting the NSL system when you tune, and more importantly, how you can use that distortion to your advantage.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 25.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-05-2021 22:35
    David & Jim: THANK YOU!!!

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 26.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-08-2021 05:40
    Nailed it! 🙂

    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 27.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 09:24
    "With most pianos, I aim from above, lowering the pitch as I put a small bit of pressure on the lever toward the strings"

    Maggie, when you do this, what is the position of your lever on a grand? I'm thinking that at 9 o'clock you automatically get some flex toward the string but at 12 (a more awkward position) you could vary the flex with more or less down pressure.

    Personally I need to kick the pounding habit and save my wrist. My latest practice has been to add a slight downward twist of the pin to the hard blow making it more effective and theoretically allowing for a softer hard blow. The wrist still hurts a bit. I think I need to go cold turkey

    ------------------------------
    John Pope
    University of Kentucky School of Music
    Lexington, KY
    ------------------------------



  • 28.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 13:23
    That's a really good question. With looser pins, I tend toward the 12:00 position because turning the lever doesn't flex the pin much, and that's what I want to do. The tighter the pin, the closer I move toward 2:00 or 10:00 depending on the piano and which hand I'm using. With grands, I tend to be right handed and have the lever between 12:00 & 2:00. 

    I think the method you just described is probably going to work for you if you don't want to go cold turkey, but you're going to have to practice and trust yourself a bit. I went through a couple months where my tunings were less stable while I was figuring it out. I feel bad about that, but I had to do it for my own health. I think I've become a better tuner for it, particularly with my listening skills. I'm no longer afraid of loud blows, nor am I desensitized by them.

    Good luck!

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 29.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-08-2021 05:37
    To me, it seems that everyone has the same experience. Obviously. We are all tuning pianos. They are just describing it differently.

    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 30.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-04-2021 02:52
    Hi Jon:

    What is in the CBL and how do I get some?

    Will Truitt

    ------------------------------
    William Truitt
    Bridgewater NH
    603-744-2277
    ------------------------------



  • 31.  RE: Hammer Technique

    Posted 05-04-2021 07:54
    Will,
    Please contact me privately.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 32.  RE: Hammer Technique

    Posted 05-04-2021 08:16
    To be clear, stability is excellent without the lube. By length of lever, do you mean lever technique only and not blows, or impact, has enough mechanical advantage to ease the string over the bearings?  That would make sense, and is definitely how I use the long lever, for minute rendering moves.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 33.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-04-2021 09:50
    Could someone define "counterbearing" for me? Do you put CBL on the felt in front of the agraffes/capo, or where the string contacts the agraffe/capo bar? or both?

    ------------------------------
    John Pope
    University of Kentucky School of Music
    Lexington, KY
    ------------------------------



  • 34.  RE: Hammer Technique

    Posted 05-04-2021 10:14
    Counterbearing, or rather the counterbearing bar,  is on the tuning pin side of the agraffe or capo.  Coming off the agraffe or capo, on the way to the tuning pin, the string traverses a secondary friction point. That secondary friction point, is the counterbearing bar. The Counterbearing bar can either terminate a calculated duplex length (between capo and counterbearing bar), or a short, 20mm or so, non-calculated duplex length. 

    A third point of friction will sometimes also be presented to the string by the string bearing directly on felt on the way to the tuning pin, after or before crossing the actual counterbearing bar.

    Counterbearing is also often referred to as the string rides up a felt covered slope as in most tenors, even if there is no actual counterbearing bar.  In the tenor, for instance, counterbearing often does not include an actual counterbearing bar...it is often just an expanse of felt creating friction between felt understring cloth and string.  The friction on this expanse of counterbearing felt, will depend on the angle that this slope creates as the string rides up towards the tuning pin.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 35.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-04-2021 19:08

    I haven't found that lubricating the friction points necessarily improves stability except that in a high(er) friction piano it removes some uncertainty about whether the segments have all moved. If you recognize a high friction situation you generally adjust and compensate. But lubricating certainly makes it easier where the reaction you get from any movement of the pin is more immediate. That both speeds things up and gives a better sense of control. 

    In addition, lubrication on the counterbearring area reduces string breakage. If you have any stubborn or slightly frozen section in the cb area it takes very little movement of the pin in raising the pitch to get that short segment to exceed the breakpoint. That's even more true if you tend to pull the pitch above the target by keeping the force on the hammer on the rotational plane and then settling the pitch back down.

    Stress on that front segment can be avoided, or reduced, by learning to move the pin in the block without the pitch actually rising and then relaxing the pin after as described in the previous thread. 

    As an aside, the biggest problems with stability in high friction situations occurs in the capo section and there's a tendency to want to test blow those sections repeatedly and hard. A simpler method is to use a hammer shank and press on the speaking length just slightly, flexing the string. Any irregularities will show up quite quickly. 



    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 36.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-04-2021 10:34
    Both, if necessary. Been doing this since the 80s.






  • 37.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-05-2021 02:31
    Why the secret?  Are you selling your own formula Jon?

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 38.  RE: Hammer Technique

    Posted 05-05-2021 21:55
    David, yes.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 39.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-05-2021 22:13
    Thanks Jon I've sent you a private message

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 40.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 04:35

    Yes. Exactly! With any notching, jabbing, or impact technique.

    Use Slow Pull. 


    Just pull it up and let go. Not fine enough? Try again until it is exactly where you want it.

    Works for me. 🙂

    Also works well for many jumpy pins and agraffes if the jump only happens once, at the beginning of the pull. 

    BTW, "Slow" Pull is a misnomer. It's actually done quite fast when it's effective. 



    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 41.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 04:31

    I used to think friction was the variable but how can it be when friction is a function of material and normal force (force pressing objects tighter at 90 degrees)?

    The materials are always the same - cast iron or brass in steel - and the normal force is fairly constant as a function of string tension and angle at the bearing points. 

    The answer is friction is fairly constant. The variable is the length of the NSL and Hooke's Law. 

    Long NSL "feels" like there's more friction. There isn't. 

    Short NSL "feels" like there's less friction. There isn't. 

    It's just physics. 

    There is of course understring felt and increased angles on some grands like Heintzman, but then again, those can be thought of as just behaving like a longer NSL. 



    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 42.  RE: Hammer Technique

    Posted 05-06-2021 07:43
    <friction is fairly constant.

    This is a blanket statement that can be misleading and frankly just plain wrong.  Friction may be somewhat constant within sections on a single piano, but constant piano to piano, irrespective of string age, and construction techniques used in the NSL...no, its misleading. Its what happens when one applies mechanical analysis but, in the interest of simplicity, but excludes critical attributes of the mechanical system.  Yes, friction is a function of material and normal force. However, it is also a function of:

    1-smoothness of the mating material (corrosion turns the surfaces into rubbing sandpaper-like surfaces...extremely high friction relative to a smooth new string) 
    2-length of friction contact - contact, because of termination angles, is usually not only a tangent point contact. Depending on the shape of the capo or agraffe actual termination, length of contact (contact area), will vary considerably in different normal termination contacts. Wide capo termination surfaces present multiples of contact area increase relative to a true "v" shaped capo. Same with agraffes, which have a large contact area, if not reprofiled. This length of contact will greatly increase friction if the surface(s) start to exhibit corrosion 
    3-friction contact again is not simply the tangent of the two materials. The string machines a groove into the capo. This means friction contact area is greatly increased in a string groove, which is contacting the string along an arc of the string's perimeter. Add length of contact to that, and a string groove in a counterbearing bar, and friction area multiplies by an order of magnitude.
    4-termination angle, increased from 12-15 deg, to sometimes 20-40 deg, increases the normal force by the sine of the included angle x tension, then multiplies this by contact area, and further multiplies it by corrosion condition of the string. Angle and attendant contact multipliers then vary as you move along the capo or agraffe field. 
    5-how many friction "events" does the string traverse on its way to the pin. Two or more high friction events in the NSL, will divide the NSL into 2 or three independent "mini-NSL's" which each have to be equalized...see European NSL construction, which can be very slow to read and tune. 

    My point here, is that, at least for me, being able to read, on each pin, the friction conditions and relative elasticities, makes achieving stability a rational thought process rather than a guessing game. 

    The point being, that, at least for my brain, when I clearly delineated all the forces involved in the tuning process: friction impediments to string movement, relative elasticities, distortions imposed on the system by the lever, angle of the lever  and its effect on distortions, stiffness of the lever, frequency range, my stability improved literally overnight...quantum leap.  None of the "1000 pianos"  foo foo applied anymore. Literally... overnight...the learning curve was reduced by an order of magnitude.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 43.  RE: Hammer Technique

    Posted 05-06-2021 17:54
    On high friction pianos I find the secret is to release tension to break the friction and get the string moving and immediately pull it up to pitch in one movement without stopping. As long as the string is moving, friction isn't working against you. But as soon as that movement has stopped, so has your ability to overcome the friction for any fine adjustment.

    Best wishes

    David P

    --
    - - - - - - - - - - - - - - - - - - - - - - - -
    David Pinnegar, B.Sc., A.R.C.S.
    - - - - - - - - - - - - - - - - - - - - - - - -
    +44 1342 850594





  • 44.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 19:32
    David - That is an interesting point and makes sense. It explains some things to me I've experienced but didn't understand. Thanks!

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 45.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 22:39
    It's been discussed before that there is static friction and dynamic friction. A pin does not move in the wood until the static friction is overcome. Once it has broken free (well, sort of free), the friction isn't static anymore but becomes dynamic because it's moving. When it stops, static friction takes over. And we begin again. The trick in tuning is to break the static friction but not allow the pin to move too far and out of control. You want to be able to turn the pin in tiny increments, and this is done by finding that point where the static friction is overcome. Jumpy pins have too much static friction, and the transition to dynamic friction is too sudden. Sometimes a smooth pull works, and sometimes not. I find that a slap with my open palm is helpful with just enough impact to turn the pin in the wood. Just enough to break the static friction and move it just a hair's breadth. Impact hammers are designed to do just that, of course. I find I have a good deal of control with my hand in this way, and I don't have to break out my Cyberhammer. Same principle with a "jerk" motion. This is the essential skill one must learn to become an expert tuner. Pushing the hammer to the downside and pounding the key might get you there, but often you'll end up sharp when it's all over. DAMHIK. Everyone has to find their "way", but in the end making small turns of the pin is the essence of expert tuning.
    Paul McCloud
    San Diego



    David Pinnegar


    On high friction pianos I find the secret is to release tension to break the friction and get the string moving and immediately pull it up to pitch in one movement without stopping. As long as the string is moving, friction isn't working against you. But as soon as that movement has stopped, so has your ability to overcome the friction for any fine adjustment.


    Best wishes


    David P


    --



    - - - - - - - - - - - - - - - - - - - - - - - -
    David Pinnegar, B.Sc., A.R.C.S.
    - - - - - - - - - - - - - - - - - - - - - - - -
    +44 1342 850594




  • 46.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 21:45

    It is my opinion from speaking with many technicians that they place much more emphasis on friction without any idea what Hooke's Law is. 

    Hooke's Law is a formidable variable in how the string renders. 

    Being wrong is a lot different than describing a model that is not 100% correct but brings to light ideas that had not been thought of before. 

    Friction is more constant than we think if we judge friction based solely on how the string renders. 



    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 47.  RE: Hammer Technique

    Posted 05-06-2021 22:49
    <many technicians that they place much more emphasis on friction without any idea what Hooke's Law is. 

    Agreed, and as this very thread started on the notion of elasticity...it is very important.  My point was, that if one is trying to "clear the air" regarding what forces we encounter and manipulate, negating the effects of friction, while talking exclusively about elasticity, is just replacing the older poor descriptions of the system, with a newer seriously incomplete description of the system.

    I do read friction events and do read elasticity when I tune...sometimes one predominates over the other, but I read them both, always, as essential forces to read and guide my lever manipulation, on each and every pin.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 48.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-06-2021 22:59
    Jim - What do you mean by "read"?

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 49.  RE: Hammer Technique

    Posted 05-06-2021 23:33
    read = relate proprioceptive touch at the lever to pitch changes in the SL. 

    If I move the 3"00 lever clockwise, and there is no SL pitch change, elasticity is part of the refusal of the pitch to change. But once I exceed the amount of clockwise force that "should have" overcome elasticity, and moved pitch, I know friction is impeding the string movement, not just elasticity.  Its having a proprioceptive sense of given how we have or haven't turned and or flexed the pin, given the length of the NSL, how much that SL pitch should have changed. If it hasn't changed, what's up? We know friction is predominant over elasticity on that pin. Distinct motions to overcome friction need  to be taken, whether flexing of the pin, impacting, touching the string with a hammer shank, lowering the pitch a good distance and then coming up again...something, has to break the static friction. We also know to be on guard that if we overshoot target, easing it down will be fraught with untrustworthy SL pitch responses. Greater movement than what we could attribute to elasticity alone has to be expected.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 50.  RE: Hammer Technique

    Posted 05-06-2021 23:41
    Another example...Low friction termination:

    PItch responds instantaneously to minute movements of the pin or even just flexing of the pin. Elasticity really does not even come into play in a way we can sense...pitch moves instantaneously. Its only in relation to adequate or too much friction, that elasticity is accentuated enough to become a force that we can perceive. The perception will be based on how much pitch changes given the amount and type of force we applied.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 51.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-08-2021 05:50

    Jim, the next time you experience pitch reacting quickly and not quickly to force, look at the NSL. 


    You mention a lot about friction and elasticity but your explanations of how to read the system are a bit confusing. 

    What I am suggesting is that considering only NSL length and how strings behave as long or short NSL (even if they are not) is a simpler model and as Einstein said, "Things should be explained as simply as possible without being more simply explained than is necessary."



    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------



  • 52.  RE: Hammer Technique

    Posted 05-07-2021 08:59
    Reading elasticity or tuning pin flex, it's the age-old discussion on whether to set the pin or set the string.

    With reduced friction after applying CBL, control is all in hammer technique. How one handles the tension in the NSL is a personal choice. I have described, earlier in the thread, how it was explained to me and I believed it and approach tuning with that method. Other methods also work, I'm just not a deliberate pin bender except in the rare circumstance when there is an overly tight grip on the pin by the block.

    When the sliding friction (grip) of the pin block far exceeds the torsion factor of the pin, tuning is very problematic. I've had instances where the pins were SO tight, the pin would twist changing the pitch +20 cents before the pin moved in the block. And this was for a concert of the Rachmaninoff 3rd! 2.5 hr to tune for the concert, 1.5 to touch-up the next day. And this was with tuning every day for the week prior for rehearsals. A new Hamburg D, BTW, in the C&A division!

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 53.  RE: Hammer Technique

    Posted 05-07-2021 11:30
    Something else I though of while driving back to the shop after picking up an action. Back Scale which Ron Nossaman brought up often.

    After the initial tuning and subsequent Van Cliburn Competition Winner's practice session/orch. rehearsal; the pianist asked why the piano had drifted so far out of tuning.
    Knowing that the tuning pins were excessively tight causing drastic pitch changes. This was a rental piano, so not knowing the skill level of previous tuners; I had to surmise that any attempt to lower the tension from the initial pull-up, drastically lowered the pitch and consequently the tension in the back scale. I demonstrated to the player by plucking each string in the rear duplex and each wire had a different pitch.

    So the second day of struggling with this tuning started with getting the back scale even. I used the highest pitch to bring the other two up. It took anywhere from +60 to +75cents to get the tension up. Upon lowering the tension, I was mindful of not overshooting pitch due to the extreme torsion induced in the pin by the high sliding friction in the block.  The next four days (after the previous night's practice/rehearsal session) where less erratic but still difficult. To sock-it-in for the performance took considerable time as mentioned.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 54.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-07-2021 09:50
    Thanks, Jim!

    ------------------------------
    Maggie Jusiel, RPT
    Athens, WV
    (304)952-8615
    mags@timandmaggie.net
    ------------------------------



  • 55.  RE: Hammer Technique

    Posted 05-06-2021 22:07
    Remember, Mark, you had mentioned twice to me that friction does differ. Some grands have long understring felt that push harshly against the NSL and others have short felt the barely touches the NSL at all. Some grands even have an extra metal termination point within the NSL thus adding more friction.

    ------------------------------
    Cobrun Sells
    cobrun94@yahoo.com
    ------------------------------



  • 56.  RE: Hammer Technique

    Member
    Posted 05-07-2021 06:33
    CBL is Jon's Counter-Bearing Lube. I was advised to use it on all tunings, and I do, except I don't bother to apply it to the bridge pin contact points of uprights (not worth it on most of the uprights I tune.) The idea is that it allows the strings easier movement over friction points, and in my experience, it does, and this makes moving the string easier. "Like power steering for your tuning hammer," as someone said. Well, in that direction, anyhow.

    ------------------------------
    Don Dalton
    Chester VT
    ------------------------------



  • 57.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-07-2021 06:37
    Does anyone put CBL on bridge pins? I wouldn't recommend it.
    Paul McCloud
    San Diego


    Don Dalton
    CBL is Jon's Counter-Bearing Lube. I was advised to use it on all tunings, and I do, except I don't bother to apply it to the bridge pin contact points of uprights (not worth it on most of the uprights I tune.) The idea is that it allows the strings easier movement over friction points, and in my experience, it does, and this makes moving the string easier. "Like power steering for your tuning hammer," as someone said. Well, in that direction, anyhow.

    ------------------------------
    Don Dalton
    Chester VT





  • 58.  RE: Hammer Technique

    Member
    Posted 05-07-2021 07:50
    I put CBL on strings at bridges. Wrong?

    Edit: Probably wrong. In Igrec's book, he recommends lubing the speaking length of the strings just before the bridges, but not at/on the bridges.

    ------------------------------
    Don Dalton
    Chester VT
    ------------------------------



  • 59.  RE: Hammer Technique

    Posted 05-07-2021 07:57
    I don't. No benefit there and probably not ideal for wood.

    I use mine anywhere there is metal to metal, or metal to felt contact.

    ------------------------------
    John Formsma, RPT
    New Albany MS

    Live not by fear or lies.
    ------------------------------



  • 60.  RE: Hammer Technique

    Posted 05-07-2021 08:14
    I would not put any liquid on a bridge other than CA if there are cracks around the pins. The bridge will be softened by lubricating liquids. Some bridges have graphite on them for lubrication.



    --
    - - - - - - - - - - - - - - - - - - - - - - - -
    David Pinnegar, B.Sc., A.R.C.S.
    - - - - - - - - - - - - - - - - - - - - - - - -
    +44 1342 850594





  • 61.  RE: Hammer Technique

    Posted 05-07-2021 08:39
    Correct, wrong. You don't want any lubricant affecting the bridge pin hole. String friction at the bridge surface or pin is not much of an issue as is at the c/b and front terminations.

    It does not creep. I have brushed it sparingly on the SL as an experiment to see if it prevents corrosion since it seems to work well in the front 'duplex' area.
    I have also experimented brushing it sparingly on tuning pins for rust prevention/elimination with no long term ill effects.

    Even with it not creeping, you still need to apply sparingly so as not to have the liquid travel along the wire or migrate beyond the c/b felt. It's also important to clean the area of dust first to prevent this migration. As John stated, metal-to-metal or felt-to-metal.  Wood and oil products are not a good combination.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 62.  RE: Hammer Technique

    Posted 05-07-2021 09:32
    hello Jon,
    would you recommend your CBL for use (like one or two drops) on tuning pins with corroded coils?
    Peter

    ------------------------------
    Petrus Janssen
    Peachtree City GA
    678-416-8055
    ------------------------------



  • 63.  RE: Hammer Technique

    Posted 05-07-2021 11:14
    My only experience with tuning pin application is to lightly brush it on. I wouldn't recommend drops as something might run down into the block. A few drops on the heal of the bristles and brush across the pins. I haven't had the need to press so hard as to include the coils in the application.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 64.  RE: Hammer Technique

    Posted 05-07-2021 11:51
    thank you Jon.
    yesterday i worked on an 1905 full size upright Fischer piano. It had been in the family since day one and the action had nothing good going for it. I rebuilt it and put it back in the piano yesterday.
    The piano's pitch was 170 cents flat at A4 and the rest was inconsistently -much- out of tune.
    I used CBL on the pressure bar and v-bar and -thankfully- used a brush to brush on a little CBL on the corroding coils.
    Tuning was effortlessly, like Don said:  power-steering.
    Great product!
    Peter

    ------------------------------
    Petrus Janssen
    Peachtree City GA
    678-416-8055
    ------------------------------



  • 65.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-07-2021 13:12
    Like I said...I don't leave home without it.

    Pwg

    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 66.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-07-2021 16:06
    Regarding treating tuning pins, I had a friend who would treat pins with Neetsfoot Oil to prevent rust. He had an excellent method to keep from over-applying. He had a small jar with a piece of thick felt (3/8's "?) at the bottom which carried the oil, he would stroke his brush across the felt so it would pick up the oil without too much wicking up on the bristles. That way he never had a problem with drips. It worked well, the oil would polymerize on the pin and coils preventing oxidation. He did it successfully for years until they changed to a formula that wouldn't fully polymerize and eventually traveled down the pin so he had to give up the practice. Great application method though.

    ------------------------------
    Steven Rosenthal
    Honolulu HI
    808-521-7129
    ------------------------------



  • 67.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-07-2021 19:55
    A good treatment for rusty tuning pins is a very light application of boiled linseed oil applied to the tops of the pins.  This will creep down the pin a bit, but if it gets into the bushing or pin block it will harden and might even be an advantage.  I have used a pin block treatment before repinning that was essentially spar varnish and it worked well.

    ------------------------------
    Blaine Hebert
    Duarte CA
    626-795-5170
    ------------------------------



  • 68.  RE: Hammer Technique

    Posted 05-08-2021 07:40
    I am very leery of any substance that dries and leaves a gunny residue to attract dirt or has a tendency to creep. CBL has only 16% metal preservative/oil and it does not creep. I use CBL solely on counter bearings, key pins and centers. I don't advocate placing it on strings or tuning pins, I have experimented on a few piano and time will tell if there was any benefit.

    One experiment I did was on a rattling, dud of a bass string. I wiped some on the wrap and sure enough, it deadened the string more but at least it got rid of the annoying rattle. I haven't been back to see if the rattling returned. But dead/dull was better than dull/rattle.  I have not had it migrate along the wire from the agraffe to the wrap.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 69.  RE: Hammer Technique

    Registered Piano Technician
    Posted 05-08-2021 05:32

    Yes. Friction does differ as you said. My point was that friction doesn't differ as much as we think based on how the string renders.

    Some of the most famous and experienced concert level piano technicians I have talked to have never heard of Hooke's Law and work based on the assumption the rendering effects are 100% due to friction. 

    I was just trying to bring that to light. Friction is not constant. It's just more constant than we think, and part of that makes sense due to the common materials, forces, and angles. 


    I hope that makes sense now. 



    ------------------------------
    Mark Cerisano, RPT
    B.Sc.(Mech.Eng.), Dip.Ed.
    https://howtotunepianos.com
    http://mrtuner.com
    1-866-678-8637
    ------------------------------