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11/11/03 Oppor-TUNE-ist Piano Service 1

PIANO SCALE EVALUATION

A DISCUSSION OF RESTRINGING PREPARATION

1Thursday, September 26, 13Welcome to a discussion of piano scale evaluation.I’m Mark Gallant, Oppor-TUNE-ist Piano Service.This presentation encompasses an important prepatory step in the restringing process.

PIANO SCALE EVALUATION

A DISCUSSION OF RESTRINGING PREPARATION

1Thursday, September 26, 13Welcome to a discussion of piano scale evaluation.I’m Mark Gallant, Oppor-TUNE-ist Piano Service.This presentation encompasses an important prepatory step in the restringing process.

AGENDA

• Scale copy • Benefits of Evaluation – Specification• Evaluation Elements• Specifications to the String Manufacturers• Data Capture

2Thursday, September 26, 13We’ll touch the topics of the old scale copy methods,Why scale evaluation and specification should be a step in restringing an instrument,The parameters of a scale that should be scrutinized,What information is needed to produce the custom bass string set,And What measurements to take from the original scale to start the analysis

AGENDA

• Scale copy • Benefits of Evaluation – Specification• Evaluation Elements• Specifications to the String Manufacturers• Data Capture

2Thursday, September 26, 13We’ll touch the topics of the old scale copy methods,Why scale evaluation and specification should be a step in restringing an instrument,The parameters of a scale that should be scrutinized,What information is needed to produce the custom bass string set,And What measurements to take from the original scale to start the analysis

SCALE COPY

• Paper patterns• Duplication• Few known parameters

– Tension– Inharmonicity– Expansion– Volume/Impedance

3Thursday, September 26, 13Many technicians reproduce the existing scale on an instrument. The plain wire sections are the easiest to reproduce faithfully by simply using the same wire gauge that’s already on the piano.The bass strings are a little more difficult to replicate if the original equipment manufacturer scale is not available. Many string winders have a good deal of history acquired from experience or manufactures or other archive methods to produce very reasonable replications of the original bass strings.The paper pattern created by stretching a large sheet of butcher or brown wrapping paper over the plate while strung and rubbing to transfer the scale data still may be used. Accuracy loss could be considerable with this method.Hey, just send in the old strings! Not a bad solution for duplication of the scale present in the piano. Shipping costs may be an issue, and unless the old strings are shipped back with the new ones, there is no quality control.Scale duplication or replication leaves the technician with minimal knowledge or understanding of the scale and at best, results in the same issues as the original. However, with out the insight evaluating the scale parametrics will give a technician… ignorance may be bliss.

SCALE COPY

• Paper patterns• Duplication• Few known parameters

– Tension– Inharmonicity– Expansion– Volume/Impedance

3Thursday, September 26, 13Many technicians reproduce the existing scale on an instrument. The plain wire sections are the easiest to reproduce faithfully by simply using the same wire gauge that’s already on the piano.The bass strings are a little more difficult to replicate if the original equipment manufacturer scale is not available. Many string winders have a good deal of history acquired from experience or manufactures or other archive methods to produce very reasonable replications of the original bass strings.The paper pattern created by stretching a large sheet of butcher or brown wrapping paper over the plate while strung and rubbing to transfer the scale data still may be used. Accuracy loss could be considerable with this method.Hey, just send in the old strings! Not a bad solution for duplication of the scale present in the piano. Shipping costs may be an issue, and unless the old strings are shipped back with the new ones, there is no quality control.Scale duplication or replication leaves the technician with minimal knowledge or understanding of the scale and at best, results in the same issues as the original. However, with out the insight evaluating the scale parametrics will give a technician… ignorance may be bliss.

Benefits of Scale Evaluation

• Control winding material changes• Better match to Historic Characteristics• Smooth out parameter curves• Correction of termination nuances or

replacement of termination points.• Stress leveling to aid stability

4Thursday, September 26, 13Why do we want to go through the hassle of collecting and evaluating the scale parameters?Because as we technicians restring an instrument we have the opportunity to make it better. Mass production of anything demands keeping the cost of manufacturing at a minimum. In the plain wire sections of a piano that translate to changing wire gauge as infrequently as possible. In the wrapped strings it means compromising some parameters such as length of exposed core wire long enough to accommodate all in-tolerance nuances in the production of the piano and/or reusable engineering for more than one instrument model.When restringing an instrument we can custom fit the scale to the uniqueness of the instrument.Some of the original strings were wound in materials that just are not available today.

Benefits of Scale Evaluation

• Control winding material changes• Better match to Historic Characteristics• Smooth out parameter curves• Correction of termination nuances or

replacement of termination points.• Stress leveling to aid stability

4Thursday, September 26, 13Why do we want to go through the hassle of collecting and evaluating the scale parameters?Because as we technicians restring an instrument we have the opportunity to make it better. Mass production of anything demands keeping the cost of manufacturing at a minimum. In the plain wire sections of a piano that translate to changing wire gauge as infrequently as possible. In the wrapped strings it means compromising some parameters such as length of exposed core wire long enough to accommodate all in-tolerance nuances in the production of the piano and/or reusable engineering for more than one instrument model.When restringing an instrument we can custom fit the scale to the uniqueness of the instrument.Some of the original strings were wound in materials that just are not available today.

Winding Material Changes

• Most common winding material today is soft copper.

• Difference in densities results in different volume, tension, inharmonicity

Steel->CopperSilnic->CopperAluminum->Copper

5Thursday, September 26, 13Many older instruments used a soft steel wire for string winding. The characteristics of the steel verses the copper used latter and mostly by string winders today, is quite significant. Replication of wrap diameters with out regard to the material change would result in a scale noticeably different in tone, volume and tension.A silver – nickel alloy and aluminum alloys have also been used to load the bass strings. WOW, the difference between aluminum and copper is very significant!

Winding Material Changes

• Most common winding material today is soft copper.

• Difference in densities results in different volume, tension, inharmonicity

Steel->CopperSilnic->CopperAluminum->Copper

5Thursday, September 26, 13Many older instruments used a soft steel wire for string winding. The characteristics of the steel verses the copper used latter and mostly by string winders today, is quite significant. Replication of wrap diameters with out regard to the material change would result in a scale noticeably different in tone, volume and tension.A silver – nickel alloy and aluminum alloys have also been used to load the bass strings. WOW, the difference between aluminum and copper is very significant!

Better Match to Historical Characteristics

• Change of core or wrap to control – Tension– Volume/impedance– Expansion – Pitch change

6Thursday, September 26, 13The main parameters that can be controlled during a restring are the selection of core and overall wrap diameters to influence tension, volume or impedance and Inharmonicity.Capturing and evaluating the original scale data may allow a technician to more closely replicate the characteristics of an historical instrument when a change in winding material is needed. A good evaluation tool will allow the technician to evaluate the scale at the designed pitch as well as any target pitch.

Better Match to Historical Characteristics

• Change of core or wrap to control – Tension– Volume/impedance– Expansion – Pitch change

6Thursday, September 26, 13The main parameters that can be controlled during a restring are the selection of core and overall wrap diameters to influence tension, volume or impedance and Inharmonicity.Capturing and evaluating the original scale data may allow a technician to more closely replicate the characteristics of an historical instrument when a change in winding material is needed. A good evaluation tool will allow the technician to evaluate the scale at the designed pitch as well as any target pitch.

Improve Parametric Consistency

• Inharmonicity Curves• Tension Patterns• Volume Curves• Across the breaks

7Thursday, September 26, 13Manufacturability was discussed earlier. The opportunity to custom fit the mass produced scale to the uniqueness of the instrument is presented to us when the instrument is restrung. Evaluation of the scale allows the technician to “smooth out the curves” of several important scale characteristics. The scale evaluation tool should present these characteristics graphically to assist in the visualization of the data.

Improve Parametric Consistency

• Inharmonicity Curves• Tension Patterns• Volume Curves• Across the breaks

7Thursday, September 26, 13Manufacturability was discussed earlier. The opportunity to custom fit the mass produced scale to the uniqueness of the instrument is presented to us when the instrument is restrung. Evaluation of the scale allows the technician to “smooth out the curves” of several important scale characteristics. The scale evaluation tool should present these characteristics graphically to assist in the visualization of the data.

Tension

8Thursday, September 26, 13These two graphs show the original scale tension in the top graph, and the tension of the scale used to restring this old Steinhauer ( a 1905 upright with steel wrapped strings).The section markers in this and the following graphs depict the double wrapped, single wrapped, tenor and treble section of the scale.The comparison shows little change in the double wrap section in tension, but a much smaller transition from single wound to plain wire and a considerably smother curve eliminating the “stair step” of the original scale.Keep in mind that the final scale must incorporate the best compromise of Tension, Volume and Inharmonicity characteristics…Let’s look at the volume curve.

Tension

8Thursday, September 26, 13These two graphs show the original scale tension in the top graph, and the tension of the scale used to restring this old Steinhauer ( a 1905 upright with steel wrapped strings).The section markers in this and the following graphs depict the double wrapped, single wrapped, tenor and treble section of the scale.The comparison shows little change in the double wrap section in tension, but a much smaller transition from single wound to plain wire and a considerably smother curve eliminating the “stair step” of the original scale.Keep in mind that the final scale must incorporate the best compromise of Tension, Volume and Inharmonicity characteristics…Let’s look at the volume curve.

Volume

9Thursday, September 26, 13The parameter of VOLUME needs a little explanation.It is a theoretical value based on a “standard” hammer and “standard” blow to produce a representation of relative volume based on mass and tension. It is a representation of loudness and sustain with out regard to the characteristics of the sound board or bearing. The inverse of volume is impedance or resistance of the string to produce sound.The JUMP from wound to plain has been eliminated. The original scale clearly demonstrates the classic stair step of holding the same wire gauge as long as possible as a compromise to manufacturing costs. As technicians when we restring, it costs us little in time or materials to change wire gauge as often as we wish.The final curve is very smooth and more closely follows an expected logarithmic curve.You may notice the graphs for volume are logarithmic. That is to say the distance from 1 to 10 is the same distance as 10 to 100. If this information was displayed in a linear mode the nuances would be lost.

Volume

9Thursday, September 26, 13The parameter of VOLUME needs a little explanation.It is a theoretical value based on a “standard” hammer and “standard” blow to produce a representation of relative volume based on mass and tension. It is a representation of loudness and sustain with out regard to the characteristics of the sound board or bearing. The inverse of volume is impedance or resistance of the string to produce sound.The JUMP from wound to plain has been eliminated. The original scale clearly demonstrates the classic stair step of holding the same wire gauge as long as possible as a compromise to manufacturing costs. As technicians when we restring, it costs us little in time or materials to change wire gauge as often as we wish.The final curve is very smooth and more closely follows an expected logarithmic curve.You may notice the graphs for volume are logarithmic. That is to say the distance from 1 to 10 is the same distance as 10 to 100. If this information was displayed in a linear mode the nuances would be lost.

Inharmonicity

10Thursday, September 26, 13Inharmonicity is the result of using real materials. Materials that have “stiffness”. The “stiffness” of the string results in an effective “dead zone” at each node of the harmonics of a given string in a given position in the scale. This dead zone is what causes the speaking length of the harmonic to be shorter than the theoretical perfect length for the harmonic resulting in the harmonic being sharp to its ideal…. Therefore referred to as a partial rather than a harmonic.WHEW! What a mouthful. Inharmonicity for the purpose of scale evaluation is expressed in cents. This deviation is multiplied for each partial. For simplicity, the second partial is 2 times the Inharmonicity Constant, the forth partial is sharp by 4 times the constant. The formula is more complex than that, but it’s a good analogy for this discussion.So look at the changes here from the original. Change from steel wrap to copper wrap is primarily responsible for better fitting the bass section. A little smoother across the bridge break and less “stair stepping”.

Inharmonicity

10Thursday, September 26, 13Inharmonicity is the result of using real materials. Materials that have “stiffness”. The “stiffness” of the string results in an effective “dead zone” at each node of the harmonics of a given string in a given position in the scale. This dead zone is what causes the speaking length of the harmonic to be shorter than the theoretical perfect length for the harmonic resulting in the harmonic being sharp to its ideal…. Therefore referred to as a partial rather than a harmonic.WHEW! What a mouthful. Inharmonicity for the purpose of scale evaluation is expressed in cents. This deviation is multiplied for each partial. For simplicity, the second partial is 2 times the Inharmonicity Constant, the forth partial is sharp by 4 times the constant. The formula is more complex than that, but it’s a good analogy for this discussion.So look at the changes here from the original. Change from steel wrap to copper wrap is primarily responsible for better fitting the bass section. A little smoother across the bridge break and less “stair stepping”.

EVALUATION ELEMENTS• Speaking Length• Core / Wrap• Material• Length of Wrap• Wrap Step• Exposed core length

11Thursday, September 26, 13Tension, Volume and Inharmonicity are calculated values produce from measurable elements of the scale.The next few slides will display how changes in these measured elements affect the calculated characteristics.

EVALUATION ELEMENTS• Speaking Length• Core / Wrap• Material• Length of Wrap• Wrap Step• Exposed core length

11Thursday, September 26, 13Tension, Volume and Inharmonicity are calculated values produce from measurable elements of the scale.The next few slides will display how changes in these measured elements affect the calculated characteristics.

Change in Material

Material Tension Volume Inharmonicity

Change of Material has greatest effect on all three major parameters

Steel 200.243 29.102 0.198

Copper 224.151 32.576 0.184

Aluminum 80.701 11.728 0.391

Change of Material has greatest effect on all three major parametersSilver-Nickel 226.542 32.924 0.183

12Thursday, September 26, 13The comparisons in this and the following slides were created by holding all other parameters of the string constant. This is not a resultant or final scale, just a comparison of change in a single element and the effects.This chart shows that a change in material significantly affects all three parameters..

Change in Material

Material Tension Volume Inharmonicity

Steel 200.243 29.102 0.198

Copper 224.151 32.576 0.184

Aluminum 80.701 11.728 0.391

Change of Material has greatest effect on all three major parametersSilver-Nickel 226.542 32.924 0.183

12Thursday, September 26, 13The comparisons in this and the following slides were created by holding all other parameters of the string constant. This is not a resultant or final scale, just a comparison of change in a single element and the effects.This chart shows that a change in material significantly affects all three parameters..

Speaking Length

Speaking Length Tension Volume Inharmonicity

Tension and Volume are directly proportional to length, Inharmonicity is inversely proportional.

53.25 233.931 33.279 0.17

53.125 232.834 33.201 0.172

Tension and Volume are directly proportional to length, Inharmonicity is inversely proportional.53 231.74 33.123 0.173

13Thursday, September 26, 13Changing the speaking length by 1/8 inch either side of center gives a very small change in the three parameters we are tracking, but its packed with good information.The small change here demonstrates the greater the accuracy of the data collection the more precise the results will be. It also shows that a minor pin misalignment may not be too serious: Tension changes only a couple of pounds,Volume change is hardly noticeable,Inharmonicity exhibits the greatest relational change.This data also shows that we are looking for something in the scale that stand out from the “noise” before we change something.These changes as small as they are show us the relationship to Speaking length:Increase in Speaking length increases tension and volume but decreases Inharmonicity.Why?More length means more mass, more mass means the tension goes up to maintain the frequency of the specific note. More mass means more energy transferred to the bridge-sound board system for more volume. Greater length for no change in diameter means the “dead zone” for each partial is realatively smaller for less Inharmonicity.

Speaking Length

Speaking Length Tension Volume Inharmonicity

53.25 233.931 33.279 0.17

53.125 232.834 33.201 0.172

Tension and Volume are directly proportional to length, Inharmonicity is inversely proportional.53 231.74 33.123 0.173

13Thursday, September 26, 13Changing the speaking length by 1/8 inch either side of center gives a very small change in the three parameters we are tracking, but its packed with good information.The small change here demonstrates the greater the accuracy of the data collection the more precise the results will be. It also shows that a minor pin misalignment may not be too serious: Tension changes only a couple of pounds,Volume change is hardly noticeable,Inharmonicity exhibits the greatest relational change.This data also shows that we are looking for something in the scale that stand out from the “noise” before we change something.These changes as small as they are show us the relationship to Speaking length:Increase in Speaking length increases tension and volume but decreases Inharmonicity.Why?More length means more mass, more mass means the tension goes up to maintain the frequency of the specific note. More mass means more energy transferred to the bridge-sound board system for more volume. Greater length for no change in diameter means the “dead zone” for each partial is realatively smaller for less Inharmonicity.

Core Tension Volume Inharmonicity

All three parameters are directly proportional. Greatest effect on Inharmonicity

51 232.943 33.217 0.19

49 232.834 33.201 0.172

All three parameters are directly proportional. Greatest effect on Inharmonicity47 232.731 33.186 0.155

14Thursday, September 26, 13Let’s mess about with the core size.Here again the larger the core the more mass so its no surprise tension and volume react the same as with speaking length.It is probably obvious to the most casual observer that an increase in core diameter will affect the relative “stiffness” of the string for the given speaking length there by directly increasing the Inharmonicity factor.

Core Tension Volume Inharmonicity

51 232.943 33.217 0.19

49 232.834 33.201 0.172

All three parameters are directly proportional. Greatest effect on Inharmonicity47 232.731 33.186 0.155

14Thursday, September 26, 13Let’s mess about with the core size.Here again the larger the core the more mass so its no surprise tension and volume react the same as with speaking length.It is probably obvious to the most casual observer that an increase in core diameter will affect the relative “stiffness” of the string for the given speaking length there by directly increasing the Inharmonicity factor.

Wrap Tension Volume Inharmonicity

Tension and Volume are directly proportional to length, Inharmonicity is inversely proportional. Greatest effect on Inharmonicity

235 243.011 34.652 0.167

230 232.834 33.201 0.172

Tension and Volume are directly proportional to length, Inharmonicity is inversely proportional. Greatest effect on Inharmonicity225 222.877 31.781 0.176

15Thursday, September 26, 13Most of the scale evaluation exercise is about the wrapped strings. Its where we have the most parameters to play with.This example has the overall wrap diameter changing by 5 mill increments. Just so we are all on the same page, a MILL is .001 inch, or a THOUSANDTH of an inch.Core and wrap diameters are expressed in MILLS as whole numbers.Back to the chart. Again messing with mass therefore changes are directly proportional. This time though, both of them show some real change.Inharmonicity is inversely proportional. Why?Changing the size of the core directly affects the “stiffness” , but, wrap is at “90 degrees” to the direction of stiffness (latitudenal vs longitudinal) and therefore has little effect on stiffness while adding mass and diameter or bulk.The difference in diameters is part of the Inharmonicity calculations with the net result of lowering the inharmonicithy for added diameter.Using the relationships of core to overall wrap diameter and the effects on tension, volume and Inharmonicity may help in the selection of the best fit universal string in a field repair.

Wrap Tension Volume Inharmonicity

235 243.011 34.652 0.167

230 232.834 33.201 0.172

Tension and Volume are directly proportional to length, Inharmonicity is inversely proportional. Greatest effect on Inharmonicity225 222.877 31.781 0.176

15Thursday, September 26, 13Most of the scale evaluation exercise is about the wrapped strings. Its where we have the most parameters to play with.This example has the overall wrap diameter changing by 5 mill increments. Just so we are all on the same page, a MILL is .001 inch, or a THOUSANDTH of an inch.Core and wrap diameters are expressed in MILLS as whole numbers.Back to the chart. Again messing with mass therefore changes are directly proportional. This time though, both of them show some real change.Inharmonicity is inversely proportional. Why?Changing the size of the core directly affects the “stiffness” , but, wrap is at “90 degrees” to the direction of stiffness (latitudenal vs longitudinal) and therefore has little effect on stiffness while adding mass and diameter or bulk.The difference in diameters is part of the Inharmonicity calculations with the net result of lowering the inharmonicithy for added diameter.Using the relationships of core to overall wrap diameter and the effects on tension, volume and Inharmonicity may help in the selection of the best fit universal string in a field repair.

Step Tension Volume Inharmonicity

Inharmonicity is greatly affected by step length. Directly Proportional

0.75 222.877 31.781 0.8

0.5 222.877 31.781 0.524

Inharmonicity is greatly affected by step length. Directly Proportional0.25 222.877 31.781 0.318

16Thursday, September 26, 13Step is the length of exposed under wrap or first layer wrap on a double wrapped string.Common step values are quarter, half , 3 quarter and 1 inch. The ration of diameters of over wrap wire to under wrap wire is general 3:1. This ratio prevents the over wrap from setting in the grooves if the under wrap was only half the diameter. This means there is a pretty significant change to account for. The table shows how dramatically Inharmonicity is affected by the step length. The greater the exposed difference the greater the Inharmonicity.The tension and volume calculations are affected so little by the step that it is not included in the calculations. That’s why those numbers don’t change

Step Tension Volume Inharmonicity

0.75 222.877 31.781 0.8

0.5 222.877 31.781 0.524

Inharmonicity is greatly affected by step length. Directly Proportional0.25 222.877 31.781 0.318

16Thursday, September 26, 13Step is the length of exposed under wrap or first layer wrap on a double wrapped string.Common step values are quarter, half , 3 quarter and 1 inch. The ration of diameters of over wrap wire to under wrap wire is general 3:1. This ratio prevents the over wrap from setting in the grooves if the under wrap was only half the diameter. This means there is a pretty significant change to account for. The table shows how dramatically Inharmonicity is affected by the step length. The greater the exposed difference the greater the Inharmonicity.The tension and volume calculations are affected so little by the step that it is not included in the calculations. That’s why those numbers don’t change

Exposed Core

Exposed Core Tension Volume Inharmonicity

Inharmonicity is greatly affected by exposed core length. Directly Proportional.

1 222.877 31.781 0.358

0.75 222.877 31.781 0.253

Inharmonicity is greatly affected by exposed core length. Directly Proportional.0.5 222.877 31.781 0.18

17Thursday, September 26, 13Exposed core length is just like step. It is another step so the relationships hold the same:Volume and tension calculations are affected very little, so little so as to not even be a part of the formula. Inharmonicity is dramatically affected by exposed core length.This would indicate that like a short step, the shortest possible exposed core seems ideal.Keep in mind two good reasons to have some exposed core:The whole string must have some “clear” room to displace during actively producing tone. WHAT??? If the wrap was right up to the bridge pin or agraff it would not vibrate well and reduce its sustain or would make a buzz.The other reason in scale alterations to leave “enough” room at the agraff or vbar end is to accommodate for elongation. Elongation is the amount of stretch the string will experience as it is brought up to and maintained at design tension.

Exposed Core

Exposed Core Tension Volume Inharmonicity

1 222.877 31.781 0.358

0.75 222.877 31.781 0.253

Inharmonicity is greatly affected by exposed core length. Directly Proportional.0.5 222.877 31.781 0.18

17Thursday, September 26, 13Exposed core length is just like step. It is another step so the relationships hold the same:Volume and tension calculations are affected very little, so little so as to not even be a part of the formula. Inharmonicity is dramatically affected by exposed core length.This would indicate that like a short step, the shortest possible exposed core seems ideal.Keep in mind two good reasons to have some exposed core:The whole string must have some “clear” room to displace during actively producing tone. WHAT??? If the wrap was right up to the bridge pin or agraff it would not vibrate well and reduce its sustain or would make a buzz.The other reason in scale alterations to leave “enough” room at the agraff or vbar end is to accommodate for elongation. Elongation is the amount of stretch the string will experience as it is brought up to and maintained at design tension.

String Specifications

• Core• Wrap Diameter• Wrap step• Loop to start of wrap• Length of wrap• Tolerances

18Thursday, September 26, 13What information does the string winder need to produce the bass string set we want?Core is pretty obvious, so is overall wrap diameter. It may be best to leave the final decision of wrap wire gauges up the winder. Specifying the step on double wrap is a good thingLoop to start of wrap is an important value as is Length of wrap. A string winder usually gives PLENTY of core at the bitter end. Bitter means unfinished or raw end, the tuning pin end.Tolerances are very important in any specification. What will be the range of error from ideal, or on the practical side, from specified, that can be acceptable? You and your supplier need to know and agree on these terms.Another value that string manufactures are requesting, rightly so, is the hitch pin diameter. It’s not a value that is used in any calculations and thereby not required by evaluation tools. It makes sense though, that the closer fit the better for tuning stability and general craftsmanship of the finished product.Another side note in specifying parameters to a string maker. Does the winder want the measurements with the string at rest or at tension? As a rebuilder, you need to have both measurements at hand. Normally, Q.A. of the received strings will be at rest conditions. Values should be double checked when the instrument is close to target pitch.

String Specifications

• Core• Wrap Diameter• Wrap step• Loop to start of wrap• Length of wrap• Tolerances

18Thursday, September 26, 13What information does the string winder need to produce the bass string set we want?Core is pretty obvious, so is overall wrap diameter. It may be best to leave the final decision of wrap wire gauges up the winder. Specifying the step on double wrap is a good thingLoop to start of wrap is an important value as is Length of wrap. A string winder usually gives PLENTY of core at the bitter end. Bitter means unfinished or raw end, the tuning pin end.Tolerances are very important in any specification. What will be the range of error from ideal, or on the practical side, from specified, that can be acceptable? You and your supplier need to know and agree on these terms.Another value that string manufactures are requesting, rightly so, is the hitch pin diameter. It’s not a value that is used in any calculations and thereby not required by evaluation tools. It makes sense though, that the closer fit the better for tuning stability and general craftsmanship of the finished product.Another side note in specifying parameters to a string maker. Does the winder want the measurements with the string at rest or at tension? As a rebuilder, you need to have both measurements at hand. Normally, Q.A. of the received strings will be at rest conditions. Values should be double checked when the instrument is close to target pitch.

Data Capture

• Speaking Length• Core & Wrap• Bridge to start of wrap• V-Bar to start of wrap• Bridge to loop

19Thursday, September 26, 13Repair Estimate Guide recommends 6 hrs to capture scale data.Accuracy in collecting and recording of the original, or as found, scale data directly affects the quality of the evaluation and final scale installed in an instrument. The terminology used in this discussion is in concert with the SCALEMASTER scale evaluation software tool kit and may need to be interpreted to fit the specific evaluation tools used . Speaking Length: the distance from the bridge pin furthest from the hitch pin for the string being measured to the edge of the agraff furthest from the tuning pin –OR- bridge pin on the top bridge furthest from the tuning pin –OR- the center of the vbar or capo d’astro bar. Simply put… termination points. Bridge to Loop: from the speaking length termination pin on the bridge.Bridge to start of wrap: speaking length termination pin on the bridge to the start of wrap (start of under wrap if double wound)V-BAR: top termination point to start of wrap. These two values are the exposed core lengths.And of course, core diameter and overall wrap diameter.How? When is the best time to get all of this data? Especially in the over strung area?Perhaps during the destructive phase. That is when taking the old strings off. Yes, that’s a commitment! It can be done solo, but is far easier with a partner.

Data Capture

• Speaking Length• Core & Wrap• Bridge to start of wrap• V-Bar to start of wrap• Bridge to loop

19Thursday, September 26, 13Repair Estimate Guide recommends 6 hrs to capture scale data.Accuracy in collecting and recording of the original, or as found, scale data directly affects the quality of the evaluation and final scale installed in an instrument. The terminology used in this discussion is in concert with the SCALEMASTER scale evaluation software tool kit and may need to be interpreted to fit the specific evaluation tools used . Speaking Length: the distance from the bridge pin furthest from the hitch pin for the string being measured to the edge of the agraff furthest from the tuning pin –OR- bridge pin on the top bridge furthest from the tuning pin –OR- the center of the vbar or capo d’astro bar. Simply put… termination points. Bridge to Loop: from the speaking length termination pin on the bridge.Bridge to start of wrap: speaking length termination pin on the bridge to the start of wrap (start of under wrap if double wound)V-BAR: top termination point to start of wrap. These two values are the exposed core lengths.And of course, core diameter and overall wrap diameter.How? When is the best time to get all of this data? Especially in the over strung area?Perhaps during the destructive phase. That is when taking the old strings off. Yes, that’s a commitment! It can be done solo, but is far easier with a partner.

Reference Illustration

Speaking Length

VbarBridgeStep

Loop to Wrap

Length of Wrap

Core Diameter

Wrap Diameter

20Thursday, September 26, 13This diagram shows the various measurement points. The terminology is used in the SCALEMASTER evaluation tool kit and should be easily translated to any other tool.The math models use are all from Dave Roberts “Caluclating Technician” articles from the Piano Technician’s Guild Journal from September 1979 to April 1981.Thank you for participating in this presentation. I hope you found some good “take away” stuff to apply to your next restring task.Look for other presentations on the website at www.oppor-tune-ist.comThis is Mark Gallant, and this is a production of Oppor-TUNE-ist Piano Services.

Reference Illustration

Speaking Length

VbarBridgeStep

Loop to Wrap

Length of Wrap

Core Diameter

Wrap Diameter

20Thursday, September 26, 13This diagram shows the various measurement points. The terminology is used in the SCALEMASTER evaluation tool kit and should be easily translated to any other tool.The math models use are all from Dave Roberts “Caluclating Technician” articles from the Piano Technician’s Guild Journal from September 1979 to April 1981.Thank you for participating in this presentation. I hope you found some good “take away” stuff to apply to your next restring task.Look for other presentations on the website at www.oppor-tune-ist.comThis is Mark Gallant, and this is a production of Oppor-TUNE-ist Piano Services.

THANK YOU

• Please write with any questions or comments to [email protected]

• Visit the web site at• www.oppor-tune-ist.com

21Thursday, September 26, 13

THANK YOU

• Please write with any questions or comments to [email protected]

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21Thursday, September 26, 13

piano scale evaluation - oppor-tune-ist.com · 11/11/03 oppor-tune-ist piano service 2 agenda •...

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