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Tensile strength and inharmonicity

  • 1.  Tensile strength and inharmonicity

    Posted 12-09-2017 00:57
    In a system where all other factors remain constant, does substituting low-tensile-strength wire (e.g. Paulello) result in a change of inharmonicity?

    I read of improvements to the sound in regard to hybrid scaling, but as I read what Paulello says, the concepts of minimizing internal amortization and achieving good spectral balance are identified as the key elements at play.

    I understand that inharmonicity varies inversely with tension in a system where wires are of the same grade of material.  If changing the tensile strength of the wire, thus setting the string at a different percentage of its breaking point, does not significantly influence inharmonicity, I have at least one factor for rationalizing tension choices in a stringing design.  If, however, inharmonicity does vary with changes in tensile strength, I need to learn how the relationship works.

    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------


  • 2.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-09-2017 05:53
    Floyd, if you were to have three unisons of equal speaking length, same guage, and tuned to exactly the same pitch; and the only difference was that each was of a differing wire type with different breaking strengths (such as Types 1, O, and M) they would each sound different.  Stephen's research has shown that there is no difference in inharmonicity.  The material compositions are different between the three, although how this is done is not publically available information.  If you change the gauge size, then you will have more familiar results

    I can't be helpful to you in a technical way, I can only say that the wire does sound  different, even the M type, which is the closest equivalent to Roslau or Mapes.  The blending is beautiful, and I think the finest wire in the world.  

    It's not that we should not pay any attention to tension when doing hybrid scaling.  And we should attend to inharmonicity also.  The most difficult thing for people to grasp when coming from the traditional way of scaling, prioritizing tension or inharmonicity, is that breaking percentage will have more effect on tonal change than these other factors.  The essence of it is that there is a goldilocks zone of optimal tone that is related to a range of BP% (PBL% as Paulello calculates it).  This PBL% will vary depending where you are in the scale, being optimal at 50% in the low bass to about 60% at the top, first plain wire at about 50% going up to about 75% at note 88.  

    In my own rescaling, I strive for the most even transitions of PBL% at or near the targets by changing wire types and gauges (wraps also in the bass), Sometimes I modify the SPL. I pay attention to tension and inharmonicity as I go along, and loudness as well.  I may make small changes based on these considerations. 

    If one were to look at my graphs of tension and inharmonicity, they usually won't be quite as smooth as they would be if I had prioritized T or IH.  But they will sound more even and blended, nonetheless.  And they will sound much better in the problem areas of the scale. And the piano as a whole will sound more balanced and more of one voice.   

    When one listens to the final product of a good hybrid rescaling, it is obvious to even the casual ear that there is very considerable improvement.  

    You have a no great shakes grand to rescale.  It is a perfect candidate to spread your wings on, and you will be surprised at how much change you can effect. 

    Will


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



  • 3.  RE: Tensile strength and inharmonicity

    Posted 12-09-2017 11:10
    Hi William,
    In Fandrich's recent Journal article he states regarding Stainless Steel music wire " 



    Is this true? Do you have any experience with stainless steel? I ask because there are numerous sources for it and it would be easy to get. Also you didn't mention impedance as a measure, I would think it could be useful.
    -chris
    #caveman

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 4.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-09-2017 13:50
    I have plenty of experience with it.

    In fact, I were doing Floyd's piano, that is exactly where I would use SS wire. 

    I fell in love with the sound of it, and the workability of it, and the tuning stability of it. I had Gregor Heller make me a set of bass strings (maybe two) using PS core wire. They were great!  However, I fell out love with it when things started breaking. By far, the most breakage was in 15.5 gauge and smaller. The breaking point is just too low for 20th century tensions and beyond.

    Admittedly, I listened to the maker's (Juan Mas-Cabre) claims a bit too willingly. The problems didn't show up until a few years later. He did warn me that it CANNOT be abused in any way, and must be tuned carefully (no yanking or overpulling, etc.) I can control that when it's under my care, but someone else...problems.

    Once the breakage became a clear issue I stopped using anything smaller than 16 gauge. So I would string the treble with Mapes and the tenor with PS. That seemed like good solution at the time.

    At present I use it only right at the bottom of the tenor at the break where I can bump up the tension and increase the diameter and still retain good tone. Now that I'm learning about the importance of breaking percent, I understand better why it sounds so good and solves certain scaling issues. I don't think that knowledge was available at the time PS was on the market.

    Anyway, it was DESIGNED AND INTENDED for the low tension 1840 - 1860 era pianos. In that context it would be beautiful. Juan was constantly trying to get the wire maker to tweak the formula somehow to make it stronger, but they said it couldn't be done beyond what they already did.

    Anyone know the modulus of elasticity for Puresound SS wire?

    Pwg

    Pwg

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



  • 5.  RE: Tensile strength and inharmonicity

    Posted 12-09-2017 15:10
    Peter,
    And?





  • 6.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-09-2017 16:16
    And what?  ☺  did I leave something out?

    Pwg

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



  • 7.  RE: Tensile strength and inharmonicity

    Posted 12-09-2017 16:19
    I see it now. For some reason only your first sentence showed up.





  • 8.  RE: Tensile strength and inharmonicity

    Posted 12-09-2017 16:50
    I'm not understanding why the Stainless Steel would be failing. Is it because of not paying attention to the BP%.  In the low tenor it's possible to bring the BP% to 50% with SS.  Which is a lot better if some scale sections are in the 25%-30% range.  
    Are people going up to 90% with SS?

    -chris
    #caveman

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 9.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-09-2017 16:56
    Hi Chris:  I didn't mention impedence, and it is of course an important consideration.

    I have not used the stainless steel wire, I started with the Paulello and have stuck with it.  I am aware of the breakage issue, and I do know people whom I respect using the wire and loving it.  

    Will

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



  • 10.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-09-2017 19:01
    Chris, 

    Basically, the SS is simply not nearly as strong as standard cast steel wire such as Mapes or Roslau. At the time I started with it (roughly 2001-2002) I didn't do much (if any) calculation of stuff. It was being marketed as "strong enough" for many (but not all) 20th century pianos. I took the plunge.

    And I loved it...at first. 

    I assume (knowing what I know now) that part of why it sounds so good is that the breaking percentage is largely in the goldilocks zone. Unfortunately after a while it doesn't seem to like the tension.

    Now, it may not actually be the tension per se. It may be slightly rough handling in the stringing process. Juan would tell me that it can't take abuse. One bend...that's it. Tools should be polished smooth to avoid nicks, etc. NO OVERPULLING! So, it is conceivable that I contributed toward the breakage myself to some degree.

    I don't mind an occasional break to repair, but 5 or 6 or more in a rebuilt piano does not go over well with the client (or me). The guy who took over my DC business in 2007 is still dealing with it. And, I had to help pay for a near complete restring of one piano that just kept on breaking (although it was being tuned by someone else who's technique I simply don't know...but that's part of the problem).

    Generally the higher gauge wire is fine because it has the strength. In fact I personally have never had a break in anything above 15.5 gauge. I routinely use it at the break to help out the transition. 

    That's my story (for the most part). I would love to hear anyone else's experience with it. I don't consider it a failure...just "college".

    Pwg

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



  • 11.  RE: Tensile strength and inharmonicity

    Posted 12-09-2017 19:28
    Thank you Peter. I will take heed of your experience. I too only plan to use it at the break as well. Thx again.
    -chris





  • 12.  RE: Tensile strength and inharmonicity

    Posted 12-09-2017 22:26
    To answer the OP,  changing only the tensile strength, while maintaining the same wire size and speaking length does not alter the inharmonicity.

    FYI...Paullelo's scaling, my own and others I know who work with hybrid wire, mostly does not adhere to what I would refer to as the "standard scaling model" developed over the last 30 yrs or so. If you look at Paullelo's scaling, the smooth lines associated with the standard model are not something that is meaningful to his model. He has chosen to focus on BP% as one of, if not the primary parameter. This, since he has varying tensile strength cores within a wire size to work with, while the standard model assumed only a single tensile strength.  Pretty lines or not they work aurally, which gives the analytic model he is using credibility, though it may make folks acquainted with the standard model scratch their heads  . 

    For myself, since inharmonicity is not something one hears, it is way way down on my list of things to pay attention to. When push comes to shove, if BP% is working smoothly, and tension is in the ballpark (showing a trend, though it could display a straight line or a jagged line), I consider the job done.

    The important thing is BP%. With that, I shoot for a trend, but do not necessarily fuss over a jagged line. I do find that if I smooth the tensions and the BP%, everything including IH looks pretty smooth…but frankly I think this smoothness exists mostly on paper…so it doesn't bug me if the lines aren't perfectly pretty.  

     Just keep in mind, when looking at Paullelo's BP%, that his numbers are expressed as "Nominal BP". Nominal meaning, he has already loaded a 25% safety factor into the Nominal number. I do not like the nominal #, because it makes it hard to talk to others using the standard model in the country. So my sheet reports actual BP%, eliminating the built in safety factor...just my preference. 

     

     




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



  • 13.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-10-2017 01:03
    Chris, I was not referring to stainless steel wire in my articles. I was referring to Paulello's low tensile strength wire. Those are two different things. I have not used stainless steel wire -- I shied away from it after hearing about the breakage problems. When properly used I have not had, nor have I heard about, these problems with Paulello's LTS wire.

    ddf

    ------------------------------
    [Delwin D] Fandrich] [RPT]
    [Piano Design & Manufacturing Consultant]
    [Fandrich Piano Co., Inc.]
    [Olympia] [WA]
    [360-515-0119]
    ------------------------------



  • 14.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-10-2017 09:48
    We are overdue for a presentation on the virtues of Paulello's wires and scaling at the annual PTG convention. I think Del may have touched on it in the second half of last year's class on piano design, but I had a schedule conflict for that period. Theory, completed pianos to play and listen to, demonstration (change a few strings in class) on the low tenor of a Yamaha G1, Steinway B, and maybe a Baldwin Hamilton. Please.
    I've suggested this to several Institute Directors but no go ("we filled the schedule already" "but I asked about this two years ago").

    ------------------------------
    Patrick Draine
    Billerica MA
    978-663-9690
    ------------------------------



  • 15.  RE: Tensile strength and inharmonicity

    Posted 12-10-2017 13:05
    Pat,

    The problem with this, is that fixing these problems is a whole system problem...board, terminations, strings, hammer appropriate to the scale, choice of wrap material.. There are so many changed parameters in my designs that one-to-one comparisons are difficult to make. Plus, in my own work,  especially small grands where this is really useful (I think), I drop the monochord tensions way down from "normal", change out copper for soft iron, float boards, etc etc. Meaning, the use of Paullelo wire is only one of the tools used to completely rethink what an appropriate sound for a small grand is, because I and my customers  are looking for exceptional pitch clarity and voice-like sustain, with living room appropriate power. 

    The same with a switch out for a G1. I wouldn't just switch out 3 notes, but rethink most of the scale, including the wraps. Then after rethinking the scale, mess with board impedance adjustments Del mentioned, and or, if necessary, consider the hard hammers, etc.  This takes me time, and 2 hours doesn't cut it. 

    I would come at this from a "small piano" presentation perspective, to show how an appropriately designed small piano can re-envision the tonal profile of a small grand. That, I'd be up to present, though not if I had to ship a piano across the country to do it.  I would find it quite interesting also, from another perspective, to have a factory G series in the room, next to a tricked out G series piano.

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



  • 16.  RE: Tensile strength and inharmonicity

    Posted 12-10-2017 12:27
    I also had a bad experience with Pure Sound stainless steel wire in a Steinway M rescale as recommended by the Pure Sound company owner.
    So far as I know the company is not in business. The web site is defunct.
    As said, it is important not to confuse Pure Sound stainless steel with Paulello wire.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 17.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-10-2017 14:43
    I have a class titled: Hybrid Wire Scales that I will be teaching for one period only at the upcoming PTG Convention. I want to bring a little mid-1970's 501 Chickering that I re-scaled to demonstrate. It also has my Patented Fully Tempered Duplex Scale. The Institute has a policy not to pay for moving instructors pianos thus I am in a quandary. The Institute does provide pianos provided by manufacturers, of course no manufacturer does work like what I am teaching about. I don't see how my class can be of real value unless the participants can hear live examples.

    The many types of Paulello high-carbon wire allow for more wound tri-chord and bi-chord unisons, and less wrap on the low singles which helps make a piano sound warmer, richer and bigger when proportioned properly across the compass.

    I will also be teaching one class each of: Fully Tempered Duplex Scale and LightHammer Tone regulation. Same Chickering needed for all. The tone and touch on this little piano is stunningly wonderful. Rich warm tone in the bass and tenor much like a bigger great old American grand. The treble is so clear, powerful and singing one just has to experience it to believe it

    I do use some Stainless wire for the very lowest plain wire strings on some scales. But no more is being made. The sound difference between stainless and high carbon steel piano wire must be due to Longitudinal mode differences. The softer the wire the less L-mode. Jim Ellis tested levels of L-mode of carried by different types of wire and stainless had the lowest of all the samples tested.

    The stainless is very fragile and when I install it I go really slow and careful not to over bend it in any direction. I have several pianos in use now for 8-10 years and no broken strings. I would never use it above middle C. Many pianos I rescale have only two notes with stainless wire; the lowest plain ones.

    I have a retired Boeing Material Scientist who is testing a sample to determine what he can about composition and any processing that may have been used.

    The evidence I have is that L-mode has a far greater significance to perceived tone quality that inharmonicity. I do seem to notice the stainless tunes in a fashion that indicates slightly lower IH.

    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------



  • 18.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-10-2017 17:42
    Ed, I'm glad you'll be teaching on the subject! Hats off to the Institute Director and Team working with you and all other instructors for the 2018 PTG Convention and Institute in Lancaster PA!

    ------------------------------
    Patrick Draine
    Billerica MA
    978-663-9690
    ------------------------------



  • 19.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-10-2017 14:53
    Ed (Sutton),

    I thought everyone here already knew the difference. Sorry if I contributed to any confusion.

    Yes, no more production. When it is gone, it is gone...unless someone can figure out how to improve its strength without destroying it's other good qualities.

    Pwg

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



  • 20.  RE: Tensile strength and inharmonicity

    Posted 12-10-2017 21:21
    I bet this is what the Scarecrow really said when he got a brain.........

    "The velocity of propagation of a wave in a string is proportional to the square root of the force of tension of the string and inversely proportional to the square root of the linear density of the string".
    -chris
    #scarecrow

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 21.  RE: Tensile strength and inharmonicity

    Posted 12-10-2017 21:35
    My wife says "the answer is 2".
    I said  "no it's not!"
    She said "Is 2."
    -chris
    True story

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 22.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-11-2017 21:52
    Having heard lots of stories about how wonderful stainless steel PureSound wire was, and how they had developed stronger versions so it could be used for such pianos as a Steinway B, I took the plunge and strung one. I was especially taken by it being stainless steel, thinking the friction over the bearing points would be far less of a problem.

    Results: more broken strings in the top two sections in one year than in all my other Bs (10 or so) in the previous ten years. I restrung those sections in standard modern wire (Mapes or Roslau). I still get a broken string or two a year in the tenor section, so I will probably restring those as well.

    I'll also note that I expected, from various people's claims, that the tuning of the lowest tenor would be more stable, "because it would be closer to breaking point." That turned out not to be true in practice, and when thinking it through (with some help from John Rhodes), it didn't make any sense, either. Since both wires are the same density, they will have precisely the same behavior with respect to tension changes associated with RH changes (however those are brought about). Furthermore, they will have the same inharmonicity, which they do, based on measurements.

    So my report was one of those warning against PureSound. The breakage problem trumped any benefit.

    ------------------------------
    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    http://fredsturm.net
    http://www.artoftuning.com
    "We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
    ------------------------------



  • 23.  RE: Tensile strength and inharmonicity

    Posted 12-11-2017 22:53
    Fred,
    Actually, the breaking could have another reason. You possibly miscalculated the BP% and Tension. You stated that Stainless steel and Roslau/Mapes have the same density. Not according to my research they don't 
    Roslau/ Mapes come in at .2794 Lbs/in3
    Regular steel is .2830 lbs/in3
    Stainless is .2900 lbs/in3  just to give you an idea here, that's getting closer to 70/30 Spring Brass which is .3079
    So if you didn't properly alter your formulas, the BREAKS will happen.
    -chris

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 24.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-12-2017 09:22
    Chris,

    I don't know a lot about this, but you seem to indicate that the SS is more dense than standard steel. What then, is the significance of the fact that the SS is physically lighter in weight (significantly) than Mapes or Roslau?

    Am I missing something?



    Fred,

    My experience in the stability dept was just the opposite. I was blown away by the amazing stability that set in after about 2 years. There was almost nothing for me to do on these pianos (except repair/replace broken strings 😂).  Granted, all were humidity controlled, which you may not have had the advantage of (I'm interested to know), which could make a big difference.

    I still don't know whether the breakage issues were due to rough handling (meaning stringing like I normally do and not being super careful about nicks and bends and banging around with coil lifter and spacer, etc.), or whether it was truly a tension issue. I simply decided it wasn't worth the time and effort to find out.

    But in a low tension situation...hmmm

    Pwg

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



  • 25.  RE: Tensile strength and inharmonicity

    Posted 12-12-2017 10:12
    If you're comparing to 5lb coils, wouldn't they both be 5 pounds? 
    What is the density of the ss wire you're using? The manufacturer should have the specs.





  • 26.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-12-2017 17:27
    I don't know but I'll try to find out. 

    Pwg

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



  • 27.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-13-2017 21:29
    Chris,

    The density of Puresound SS wire is 7.97g /cm3

    Also the modulus of elasticity is 187.5 kN/mm2

    E-mod for regular wire is 205

    I'm curious if anyone has the comparative e-mod, etc for paulello wires.

    Pwg

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



  • 28.  RE: Tensile strength and inharmonicity

    Posted 12-13-2017 23:18
    Peter,
    So yes that's pretty much the same density I have. I had 8.03 g/cm3 for SS.
    I'm curious how useful e mod is for you. Since the main concern is rupture. A BP% formula, i would think, is good for that.
    I've noticed that in the other string instrument trades they have shifted focus away from the tension formula, but instead the use of a wave Velocity formula has become quite popular. This measurement is tension and linear density based and how those two influence the longitudinal wave speed. I have been writing a formula that adapts to the piano. 
    The first chart was interesting on this 5' 4" Heintzman Grand.

    Still in development.
    -chris

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 29.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-14-2017 15:02
    Peter,
    My situation is not humidity controlled. We have a regular seasonal cycle between 10% and 60%. I have 12 Steinway Bs in that environment. The one with PureSound behaves like the others, with the low tenor moving 25 - 30¢ sharp, then reversing.

    Chris,
    I grant you that the wire densities of stainless and music wire are not "precisely" the same, but that 3 - 4% difference is not enough to affect changes in tuning behavior in any noticeable way. And the density has next to nothing to do with strength and breaking point. Music wire has its strength due to the working it undergoes during the drawing process. The fact that stainless steel and spring brass have similar densities, does mean that they would need to have similar tensions for the same length, diameter, and pitch, but that's all it means. Nothing to do with whether they will break at that tension. Without the working, steel wire of whatever alloy would/will not withstand the tensions of modern pianos.

    ------------------------------
    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    http://fredsturm.net
    http://www.artoftuning.com
    "We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
    ------------------------------



  • 30.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-14-2017 15:44
    Fred,

    I see. My experience has been with pretty good humidity control.

    Chris,

    I don't know nuttin' about e-mod. It was touted to me as a major reason the wire sounded so good. (And I do agree that it sounds good). 

    Interestingly in reviewing the tensile strength of each gauge, the highest BP% I used was about 70%. Most were down around 60% or so. So I still don't quite understand why there would be so much breakage.  I guess though that the factual tuning process might hike that load to 80% or so temporarily which might be responsible. Still too risky for regular modern usage.

    It did solve some serious longitudinal mode issues though. That was nice.

    Peg

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



  • 31.  RE: Tensile strength and inharmonicity

    Posted 12-14-2017 20:41
    Peter,

    I don't know nuttin' about e-mod. It was touted to me as a major reason the wire sounded so good. (And I do agree that it sounds good).

    Interesting, since every wire type paulello has is listed with the same E-mod. 


    Interestingly in reviewing the tensile strength of each gauge, the highest BP% I used was about 70%. Most were down around 60% or so. So I still don't quite understand why there would be so much breakage.  I guess though that the factual tuning process might hike that load to 80% or so temporarily which might be responsible. Still too risky for regular modern usage.

    Since BP% is a ratio, I would think the same basic rules apply of creating a safety factor and not go above 60%. I think 66% MAX was recommended in Pscale?  At the break i've seen some scales down around 27%, so choosing a different tensile strength wire to bring the PB% up a bit would be a choice. I wouldn't go crazy aiming for 60% on every note personally. I aim for smoothing and raising the curve to blend. I generally try to stay close to the original and not stray too far.

    It did solve some serious longitudinal mode issues though. That was nice.

    Until it broke!!

    -chris

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 32.  RE: Tensile strength and inharmonicity

    Posted 12-14-2017 20:22
    Fred,

    I agree with everything you said except:
    I grant you that the wire densities of stainless and music wire are not "precisely" the same, but that 3 - 4% difference is not enough to affect changes in tuning behavior in any noticeable way.
    Maybe not tuning behavior, but certainly participates in scaling choices.

    And the density has next to nothing to do with strength and breaking point.
    Uhm... it's built in the PB% formula, as is pi and the acceleration of gravity. 

    Music wire has its strength due to the working it undergoes during the drawing process. The fact that stainless steel and spring brass have similar densities, does mean that they would need to have similar tensions for the same length, diameter, and pitch, but that's all it means. Nothing to do with whether they will break at that tension. Without the working, steel wire of whatever alloy would/will not withstand the tensions of modern pianos.
    What I do is break strings, and adjust the constants in the formula to represent the actual  wire i'm working with. In the breaking percent formula the constant varies (so far as I have seen in the gold series by mapes) from 1.671 to 1.625. 
    -chris

    ------------------------------
    A hunter's drumbeat steers the stampeding herd,
    His belly growls in hunger to what he sees.
    The mammoth aware blows his mighty trumpet,
    But alas, the caveman tickles the ivories.

    chernobieffpiano.com
    865-986-7720
    ------------------------------



  • 33.  RE: Tensile strength and inharmonicity

    Posted 12-19-2017 18:42
    How much leeway is there on the sweet spot?  I'm analyzing another grand here, also from 1925, that has a scale that is pretty consistently tensioned  throughout the plain wire section, with an average in the mid to high 160s, right up to about note 68.  If I use the existing design, but sub in type 0 wire, I end up with a nice % of BP profile, except at A4 and A5 the %BP is 2 to 3% higher than the limits Paulello specificies (63.3% at A4, vs 60%, and 72.7% at A5, vs 70%).  Since things are working so nicely with tension and inharmonicity, I'm inclined to put up with this deviation.  Will I regret it?

    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------



  • 34.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-19-2017 19:59
    Are you talking Breaking Percentage (BP)  or Practical Breaking Load Percent (PBL%)? 

    As PBL%, I would say not to worry.  

    Will Truitt

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



  • 35.  RE: Tensile strength and inharmonicity

    Posted 12-19-2017 22:15
    Hi Will. I am indeed referring to PBL%. My concern isn't about risk of breakage, but rather where the sweet spot is for optimal tone characteristics.

    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------



  • 36.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-20-2017 05:56
    Floyd:

    From Paulello's website,

    "The stress rate of the ocre wire of the bass strings should remain with 50 to 55...."

    "50% for the first plain string to a maximum of 60% at A4.
    65% at A5
    70% at A6
    75% at A7
    80% at A8"

    In practice on real pianos, sometimes these figures are exceeded, but not by large numbers.  Generally, even then, we are still well below the breaking point or elastic limit.

    Will

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



  • 37.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-19-2017 21:32
    I wouldn't put the weaker wire types above note 35 or so unless it was an unusually quite short scale like a couple of Mathuseks grands I have seen. The higher deflection angle the closer hammer strike produces will adversely fatigue the wire.

    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------



  • 38.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-20-2017 06:10
    I will respectfully disagree with my friend Ed on this one.  While I have no doubt that he gets the results he seeks with his instruments and they are excellent instruments, I have been less conservative with the use of Type O as one ascends the scale.  I have gone up to note 52, 64, and even 82 on a Steinway O.  All with good tonal results.  My end points are calculated to stay within Paulello's PBL% limits.  The existing SPL in a piano largely determines where the end point will be.

    The Paulello wire has been around for about 25 years, my use only for about 6 years.  I will have to wait and see on the fatigue.  This far I have had no breakage issues.

    Will Truitt

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



  • 39.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-21-2017 10:33
    Okay...

    Is it reasonable to conclude that many (not all of course) of our scaling/tonal/voicing issues of today (in our rebuilds) find their source largely in the fact that the wire we have today is so much stronger and stiffer than wire from 100 - 150 years ago (when these things were designed)?  

    OR am I over simplifying?

    Pwg


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



  • 40.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-21-2017 23:40
    No Peter I don't think you are oversimplifying. One can see a general trend to longer scales as the strength of wire increased. Fully modern piano wire placed at a low break point is prone to hoots and screeches.

    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------



  • 41.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-22-2017 10:22
    And is it possible that the major reason for this strength increase is so that factories can work faster, abuse the wire "without damage" and reduce breakage, etc That would complicate the process? 

    Or is there some other more logical explanation I might be overlooking?

    Pwg

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



  • 42.  RE: Tensile strength and inharmonicity

    Posted 12-22-2017 13:13
    I just learned today that we have a distributor for Paulello wire here in Canada -- JD Grandt.

    ------------------------------
    Floyd Gadd
    Regina SK
    306-502-9103
    ------------------------------



  • 43.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-22-2017 13:33
    I am interested in the fact that the Paulello wire has the same modulus of elasticity that the SS Puresound wire has. I wonder how they did that?

    Pwg

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



  • 44.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-22-2017 14:41
    Telepathy.

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



  • 45.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-22-2017 19:06
    LOL!

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



  • 46.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-23-2017 20:14
    Arno Patin was a member of the Detroit/Windsor chapter, and I know he
    has sold his shop and moved out West, or somewhere.?? Is he still the
    American distributor of Paullelo wire??????? Clark

    --
    Clark A. Sprague, RPT www.clarkspianoservice.com




  • 47.  RE: Tensile strength and inharmonicity

    Posted 12-23-2017 20:45
    No. Paullelo pulled his distributorship from Arno, for some reason. US customers order directly from the website and France, unless something has changed that I am not familiar with.  Shipping and fulfillment from France is amazingly fast, though.

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



  • 48.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-24-2017 04:37
    Clark and Jim:

    Our trusty bass string supplier JD Grandt has been the Paulello supplier since early last summer - I'll be getting about a dozen 2 Kg. reels from him in about a week, due to your insidious influence Jim, ahem......  He can get us whatever we want, along with his usual Paulello cores for his fabulous bass strings.

    Stephen is insanely busy these days and not always as responsive to emails as he used to be.  He is building a new 170 cm grand.  In November he recieved an order from the Musikverein Vienna for three Opus 102 concert grands.  (That hall is the legendary home of the Vienna Philharmonic Orchestra).  Until recently, all my orders have been fulfilled by Stephen.  I suspect he would prefer that we fulfill our orders through JD Grandt.  I am hoping he can shepherd an order for some soft iron wrap bass strings through Heller for me.

    Clark, here is contact info for Arno if you desire to contact him:    503 866 7909 

    arnopianos@gmail.com 

    Will Truitt       


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



  • 49.  RE: Tensile strength and inharmonicity

    Registered Piano Technician
    Posted 12-24-2017 10:15
    Thank you, Jim and William.  We had a couple of meetings at Arno's shop, and one at a store where he presented Paullelo's wire, and his Abacus software, and he seemed like a very nice and knowledgable guy.  I never heard what happened, except he was building a grand from scratch, commissioned by some doctor in Detroit, and then it was finished and he left.  Just wondered.  Thanks for the info.   Happy Holidays!     Clark

    ------------------------------
    Clark A. Sprague, RPT
    Bowling Green, OH
    www.clarkspianoservice.com
    ------------------------------