Pianotech

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.    

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.  

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

A friend repairs clocks. He took an old family bracket clock away to try to find out why it randomly stopped. He showed me how the 18th century cogs were a different shape to the profile of modern cog teeth, and how a previous repairer had replaced a cog with the modern profile, the brass of which had become burred thereby. That's commonsense stuff of course. But he went on to explain how in clock making you never have two cogs together of the same material, steel damaging steel and brass damaging brass, but steel mating with brass being long lasting and not wearing away. Of course with the tension of piano strings brass at friction points is out of the question. . . . 

Best wishes

David P

------------------------------
David Pinnegar BSc ARCS
Curator and House Tuner - Hammerwood Park, East Grinstead, Sussex UK
antespam@gmail.com

Seminar 6th May 2019 - http://hammerwood.mistral.co.uk/tuning-seminar.pdf "The Importance of Tuning for Better Performance"
------------------------------

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

<Of course with the tension of piano strings brass at friction points is out of the question. . . 

Agraffes are brass. Fazioli's capo is a sharp V shaped brass insert. Many rebuilders use brass half rounds as counter bearing (I don't anymore)

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

Original Message:
Sent: 07-03-2019 06:03
From: David Pinnegar
Subject: String friction over metal bearing surfaces

A friend repairs clocks. He took an old family bracket clock away to try to find out why it randomly stopped. He showed me how the 18th century cogs were a different shape to the profile of modern cog teeth, and how a previous repairer had replaced a cog with the modern profile, the brass of which had become burred thereby. That's commonsense stuff of course. But he went on to explain how in clock making you never have two cogs together of the same material, steel damaging steel and brass damaging brass, but steel mating with brass being long lasting and not wearing away. Of course with the tension of piano strings brass at friction points is out of the question. . . .

Best wishes

David P

------------------------------
David Pinnegar BSc ARCS
Curator and House Tuner - Hammerwood Park, East Grinstead, Sussex UK
antespam@gmail.com

Seminar 6th May 2019 - http://hammerwood.mistral.co.uk/tuning-seminar.pdf "The Importance of Tuning for Better Performance"

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

I had a Fender guitar, at the nut had a linear roller bearing instead of a solid bone or plastic.  Almost completely friction-less. I wonder how something like that would work on a piano.  Have roller bearing rods under the strings at the capo.  Expensive addition, but would remove a tremendous amount of friction on string movement. I think on a piano you would need a triangular setup, 2 rollers supporting the top "capo" bearing. One set for each note.  They could be built as modular units, same design for each note, just pop into place.  Simple alignment pins would be all that was needed in the piano frame.

------------------------------
Jeffrey Gegner
Tipton IN
765-860-5900
------------------------------

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Some friction, I think is useful. Otherwise the bandwidth where the pin placement is correct is too small and hard to hit.  Most of my thinking about this is trying to find the sweet spot, of some friction, but not too much.

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

Original Message:
Sent: 07-03-2019 10:19
From: Jeffrey Gegner
Subject: String friction over metal bearing surfaces

I had a Fender guitar, at the nut had a linear roller bearing instead of a solid bone or plastic.  Almost completely friction-less. I wonder how something like that would work on a piano.  Have roller bearing rods under the strings at the capo.  Expensive addition, but would remove a tremendous amount of friction on string movement. I think on a piano you would need a triangular setup, 2 rollers supporting the top "capo" bearing. One set for each note.  They could be built as modular units, same design for each note, just pop into place.  Simple alignment pins would be all that was needed in the piano frame.

------------------------------
Jeffrey Gegner
Tipton IN
765-860-5900

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Jim-
This is a good teaching demo.
Sorta by definition, friction is always going to be "rough" at some level.
It is this quality that makes fine tuning possible, if we can get the roughness at the right level, not too rough, not too smooth.
I'll be curious what you find with the co-polymer.

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

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Jim

Two things. 

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789
------------------------------

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Right...similar discussion different thread. Every piano and every section within each piano has different geometries coming off the capo to the pin. So you mock it up using strings (or thread), various thicknesses of wood shims, and the angle gauges I mentioned in the Mason thread to figure out what the front should look like. Then order the thickness(es) your shims turned out to be. I buy 1/2" stock and dimension it on the table saw as per my custom requirements, rather than buy lots of varying thicknesses.


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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Well I never...
I've been accused of a lot of things but never once has my contact point been impugned. :-)

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

Original Message:
Sent: 07-03-2019 18:46
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

oh dear!

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

Original Message:
Sent: 07-03-2019 18:51
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Well I never...
I've been accused of a lot of things but never once has my contact point been impugned. :-)

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

Original Message:
Sent: 07-03-2019 18:46
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Could someone post a few pics of these co-polymerisms?

Pwg

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

Original Message:
Sent: 07-03-2019 21:52
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

oh dear!

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

Original Message:
Sent: 07-03-2019 18:51
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Well I never...
I've been accused of a lot of things but never once has my contact point been impugned. :-)

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

Original Message:
Sent: 07-03-2019 18:46
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

Last year I posted a thread titled Co polymer Duplex (the things this forum makes me do) with several photos. If you type Co polymer duplex in the search bar you can find it in the first few results.

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

Original Message:
Sent: 07-04-2019 21:56
From: Peter Grey
Subject: String friction over metal bearing surfaces

Could someone post a few pics of these co-polymerisms?

Pwg

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

Original Message:
Sent: 07-03-2019 21:52
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

oh dear!

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

Original Message:
Sent: 07-03-2019 18:51
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Well I never...
I've been accused of a lot of things but never once has my contact point been impugned. :-)

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

Original Message:
Sent: 07-03-2019 18:46
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

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

Original Message:
Sent: 07-04-2019 22:28
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Last year I posted a thread titled Co polymer Duplex (the things this forum makes me do) with several photos. If you type Co polymer duplex in the search bar you can find it in the first few results.

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

Original Message:
Sent: 07-04-2019 21:56
From: Peter Grey
Subject: String friction over metal bearing surfaces

Could someone post a few pics of these co-polymerisms?

Pwg

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

Original Message:
Sent: 07-03-2019 21:52
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

oh dear!

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

Original Message:
Sent: 07-03-2019 18:51
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Well I never...
I've been accused of a lot of things but never once has my contact point been impugned. :-)

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

Original Message:
Sent: 07-03-2019 18:46
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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

From a horrible no-name my client's dad won at a poker game. We are working our will on this sucker...utterly untuneable with entire tenor over 45 deg termination angles, and other sections 35 deg plus. This is where co-polymer offers something no other counterbearing substance offers.

Treble was 35 deg +. Ground off the cast iron counterbearing, ground the plate to angle the leading edge down a bit, add co-polymer to achieve 20-25 deg termination angle. Co-polymer in this situation allows 25 deg termination angle to render with some friction but not too much. At lower termination angles 12-15 deg, the co-polymer may offer too little friction. To increase friction, increase width of the co-polymer bearing surface, and perhaps add some dense felt to to bear on after the string exists the co-polymer.  

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

Original Message:
Sent: 07-05-2019 09:36
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

From my current Chickering 122

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

Original Message:
Sent: 07-04-2019 22:28
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Last year I posted a thread titled Co polymer Duplex (the things this forum makes me do) with several photos. If you type Co polymer duplex in the search bar you can find it in the first few results.

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

Original Message:
Sent: 07-04-2019 21:56
From: Peter Grey
Subject: String friction over metal bearing surfaces

Could someone post a few pics of these co-polymerisms?

Pwg

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

Original Message:
Sent: 07-03-2019 21:52
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

oh dear!

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

Original Message:
Sent: 07-03-2019 18:51
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Well I never...
I've been accused of a lot of things but never once has my contact point been impugned. :-)

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

Original Message:
Sent: 07-03-2019 18:46
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Re Karl's small contact point, I agree that a longer flatter profile would help lessen the groove formation. When the co-polymer is a wider contact point, if you want to change string spacing after raising tension, since the indentation is minor at the front contact, simply pushing the wire sidewise, allows you to form a new indentation in the new position, at tension.

SInce the lubricity is so high, increasing the contact point can actually do some good regarding adequate friction. On the other hand, increasing contact with metal-on-metal would be a disaster. So the co-polymer and metal behave very differently...which is the whole point.  Just keep that "different material/different behavior" concept in mind as you work the details in your particular situation.

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

Original Message:
Sent: 07-03-2019 18:06
From: Karl Roeder
Subject: String friction over metal bearing surfaces

Mr. Gadd,
In a Baldwin Model E I re-strung last summer I replaced the bent brass counterbearing (front duplex) bars with co-polymer and it was a significant upgrade over the original material. I used a piece 1/2" thick and cut it to shape on the bandsaw and finished the shape with sand paper of various grits finishing with 600 grit. Not only is the feel of the tuning much smoother but the previously noisy capo section is remarkably clean sounding with little to no re-shaping of the capo. Were I to do it today I would probably make the pieces flatter on top with a little bit longer contact point than the original brass pieces. As it is the new pieces are working just fine with the co-polymer shaped pretty much the same as the original metal bars. One point to mention is that with a small contact point the strings will form a distinct groove in the co-polymer very quickly so you will only have one shot at spacing them on the duplex. A longer flatter profile should help with this.

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

Original Message:
Sent: 07-03-2019 17:36
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

Whoops, I see I'm not in the thread I thought I was in.  By "this project", I am referring to the one in the thread about Mason & Hamlin Treble Counterbearing Inserts.

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

Original Message:
Sent: 07-03-2019 17:34
From: Floyd Gadd
Subject: String friction over metal bearing surfaces

I am inclined to  use co-polymer on this project.  If I were to buy a 12" by 12" inch piece, what thickness would you recommend?  The tallest of the existing counter bearing bars measures about .3" in height

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

Original Message:
Sent: 07-03-2019 15:02
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

Co-polymer on piano wire turns out to be a smooth draw. None of the sandpaper like grating of any of the metal on metal interfaces. This is one reason (there are more) why I will sometimes make counterbearing bars out of co-polymer.  That is because adding a second dry metal-on-dry metal grating friction point to the primary metal -on-metal termination, as is standard practice, breaks what I call the stabilizing length between primary termination and tuning pin, into several independent string segments, each with its own sticky-ness profile. This, in my opinion invites misreadings of the various segments when trying to equalize tension...especially when some of those segments give no feedback whatsoever.

Co-polymer really helps in some circumstances, but one must read the whole system to know whether the polymer would be useful, superflous,or present too low a friction.   The whole rendering scenario is really quite an interesting, important and complicated system. The solutions are different for each piano.

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

Original Message:
Sent: 07-03-2019 12:51
From: Willem Blees
Subject: String friction over metal bearing surfaces

Jim

Two things.

First, this is just my guess, but perhaps the reason for the scraping sound is because that while the metals may appear to be smooth, in actuality, all metals have burrs. If you put brass and polished steel, like piano wire, and under a high power microscope, you can see that they are very rough. When those rough surfaces scrape against each other, they will create a sound.

Second, how this scraping effects us in our business is something all of us would interested in. If you are so inclined to take the time to do the research, I would encourage you to apply for a PRG Foundation Research Grant, and write a paper on your findings.  (The Foundation is in the process of changing some of the parameters of the grant, but that should be finalized after the convention. So wait until sometime in August to apply).

Good luck.

Wim

------------------------------
Willem "Wim" Blees, RPT
Mililani, HI 96789

Original Message:
Sent: 07-02-2019 20:50
From: Jim Ialeggio
Subject: String friction over metal bearing surfaces

I was messing around today, after stringing, while forming string bends, at the capo and agraffes. I use a string hook on the agraffe sections, but use a brass rod, or something like that, from under the strings in the capo section. I usually use a brass rod to do this forming of the centenary curve off of the termination on both sides of the capo. But, I've been mystified as to why the brass feels so scrapey, while doing this, and don't like the scrape. It scrapes despite polishing the brass working end of the tool.

So I tried other metals, steel and carbide...both harder than brass, carbide harder than the strings. The nature of the friction, in all the metals, was interesting in that they all scraped, and the scrape was jumpy. Actually, is was a very coarse scrape, and not a smooth interaction at all...including brass. Brass has the highest lubricity, but it still scrapes hard, and moves in a non-smooth catchy-jumpy way, brand new strings and polished metals notwithstanding. The harder metals were higher friction than the brass, and even jumpy-er than the brass. I ended up making a maple tool, which needed to be resurfaced several times as the strings disfigured the working end.

The thing that really caught my attention was the jumpy-ness of the dry scrape. It really makes me look at the nature of metal to metal string friction in tuning.

Metal to metal movement, even with new materials is a grinding, jumpy event. It is not a smooth rendering under any circumstance, unless there is serious lubrication between the two metals...something that is hard to achieve for any length of time on a piano termination. No wonder strings get hung up on the terminations the way they do.

Like so many "really-oughta-be" notions in piano land, how the materials actually behave, is often opposed to the notions I have imposed on how I think the materials "really-ought-a" behave, Makes reading the pin and string segment movements in tuning a more rational exercise.

At this point,  I don't believe there is any truly smooth movement over friction points, in piano string rendering...its jumpy, unto really jumpy, depending on the lubricity of the mating surfaces, and condition of the surfaces.  I do not think overcoming static friction releases the string to  move smoothly over the friction point. It moves, yes, but even as it moves, it scrapes, grinds and catches randomly as it moves (or doesn't move)  through the termination. At the end of the lever, it seems to feel smooth...one of those never ending "HA, I gottcha" impressions pianos pull off on us all the time.

I will experiment with metal on co-polymer tomorrow...see if it scrapes or moves smoothly.

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