Re: Bent peg box
Dear Michael, Thank you for posting. Please see comments below. Best regards, Marion -Original Message- From: Michael Thames <[EMAIL PROTECTED]> Sent: Mar 15, 2005 6:34 AM To: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> Cc: Lute List Subject: Re: Bent peg box >Michael >Were the old swan necks repaired or left in their >deformed >state, assuming it is possible to tell this from looking at >it? Marion, I personally drew up some plans of the Yale Jauch, and noticed the extension was in absolute perfect playable condition. There were other problems with it but the neck was fine. Also Hoppy Smith made a recording using the 1755 Widhalm with a swan neck, as well as the swan neck Hoffman, and the Martin Brunner. The only problems I've heard associated with swan necks were made by contemparie makers, who used the wrong kind of woods, and didn't copy the design properly, and this only in the early days. Now everyone has it down. ++Do you know what kind(s) of wood they used? What was the design difference? I used the word explode, but you seem to give the impression that the swan neck will self destruct, which obviously isn't true. ++Obivously not. I did not mean to imply this. Small distortions do not ruin an instrument. I have seen some (very) cheap guitars made incorrectly that all but self distructed. They made a gradual transition over the years from playable practice instrument to wall hanger via bent neck (not swan neck). BTW are you a lute maker as well? ++No, but I have been known to repair a few instruments and make a couple of cases. best, All the Michael Thames www.ThamesClassicalGuitars.com - Original Message - From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> To: "Michael Thames" <[EMAIL PROTECTED]> Cc: "Lute List" Sent: Tuesday, March 15, 2005 12:28 AM Subject: Re: Bent peg box > Dear Michael, > > Whereas some people think it's a problem, others see it as > an advantage. Like so many things, there are advantages > and disadvantages. How does a luthier compensate? > Assuming you did not like this effect, what kind of a repair > would the luthier do to fix it? Have you had this done and > is it expensive? (So far, I like mine the way it is, unless > someone can convince me that it is really a bad thing.) > > I hope it lasts longer than I will. If it falls apart that fast > I've got problems. :) > > It is not clear how my explanation sounds like the lute will > explode. This is a very gradual effect. > > Were the old swan necks repaired or left in their deformed > state, assuming it is possible to tell this from looking at it? > > Best Regards, > Marion > > -Original Message- > From: Michael Thames <[EMAIL PROTECTED]> > Sent: Mar 14, 2005 8:39 PM > To: "Dr. Marion Ceruti" <[EMAIL PROTECTED]>, > Richard Corran <[EMAIL PROTECTED]>, > Lute List > Subject: Re: Bent peg box > > ++In reference to the deformation that occurs in swan-neck > lutes, we have a slightly non-equilibrium situation. The forces > are not exactly balanced and over a period of time the string > tension overcomes the rigidity of the neck. It will overpower the > neck in the place of least resistance, namely in the swan part of > the neck > >Marion, >This isn't a problem. Of course the swan neck pegbox will bend > forward under initial tension. A lute maker will compensate for this, once > everything is adjusted it will last longer than you. You make it sound like > the whole thing will explode. Of course, Everything's impermanent, at some > point, but so far the swan neck lutes I've seen built 250 years ago are > fine. > Michael Thames > www.ThamesClassicalGuitars.com > - Original Message - > From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> > To: "Richard Corran" <[EMAIL PROTECTED]>; "Lute List" > > Sent: Monday, March 14, 2005 3:16 PM > Subject: Re: Bent peg box > > > > Dear Richard, > > > > Please see my comments below ++. > > ___ > > There are a number of misunderstandings about the forces on a peg box. > > > > First of all the only force transmitted to the peg box comes from the > > strings. > > > > ++The other forces besides the transmited force are friction and the > > electrostatic forces inside the molecules that maintain rigidity in > > the neck, pegs, etc. without which the neck would collapse when the > > tension was applied. These forces are equal and opposite to the applied > > force, resulting in an equilibrium situation in which there is no > > apparent change. > > > > Bending them a
Re: Bent peg box
>Michael >Were the old swan necks repaired or left in their >deformed >state, assuming it is possible to tell this from looking at >it? Marion, I personally drew up some plans of the Yale Jauch, and noticed the extension was in absolute perfect playable condition. There were other problems with it but the neck was fine. Also Hoppy Smith made a recording using the 1755 Widhalm with a swan neck, as well as the swan neck Hoffman, and the Martin Brunner. The only problems I've heard associated with swan necks were made by contemparie makers, who used the wrong kind of woods, and didn't copy the design properly, and this only in the early days. Now everyone has it down. I used the word explode, but you seem to give the impression that the swan neck will self destruct, which obviously isn't true. BTW are you a lute maker as well?best, All the Michael Thames www.ThamesClassicalGuitars.com - Original Message - From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> To: "Michael Thames" <[EMAIL PROTECTED]> Cc: "Lute List" Sent: Tuesday, March 15, 2005 12:28 AM Subject: Re: Bent peg box > Dear Michael, > > Whereas some people think it's a problem, others see it as > an advantage. Like so many things, there are advantages > and disadvantages. How does a luthier compensate? > Assuming you did not like this effect, what kind of a repair > would the luthier do to fix it? Have you had this done and > is it expensive? (So far, I like mine the way it is, unless > someone can convince me that it is really a bad thing.) > > I hope it lasts longer than I will. If it falls apart that fast > I've got problems. :) > > It is not clear how my explanation sounds like the lute will > explode. This is a very gradual effect. > > Were the old swan necks repaired or left in their deformed > state, assuming it is possible to tell this from looking at it? > > Best Regards, > Marion > > -Original Message- > From: Michael Thames <[EMAIL PROTECTED]> > Sent: Mar 14, 2005 8:39 PM > To: "Dr. Marion Ceruti" <[EMAIL PROTECTED]>, > Richard Corran <[EMAIL PROTECTED]>, > Lute List > Subject: Re: Bent peg box > > ++In reference to the deformation that occurs in swan-neck > lutes, we have a slightly non-equilibrium situation. The forces > are not exactly balanced and over a period of time the string > tension overcomes the rigidity of the neck. It will overpower the > neck in the place of least resistance, namely in the swan part of > the neck > >Marion, >This isn't a problem. Of course the swan neck pegbox will bend > forward under initial tension. A lute maker will compensate for this, once > everything is adjusted it will last longer than you. You make it sound like > the whole thing will explode. Of course, Everything's impermanent, at some > point, but so far the swan neck lutes I've seen built 250 years ago are > fine. > Michael Thames > www.ThamesClassicalGuitars.com > - Original Message - > From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> > To: "Richard Corran" <[EMAIL PROTECTED]>; "Lute List" > > Sent: Monday, March 14, 2005 3:16 PM > Subject: Re: Bent peg box > > > > Dear Richard, > > > > Please see my comments below ++. > > ___ > > There are a number of misunderstandings about the forces on a peg box. > > > > First of all the only force transmitted to the peg box comes from the > > strings. > > > > ++The other forces besides the transmited force are friction and the > > electrostatic forces inside the molecules that maintain rigidity in > > the neck, pegs, etc. without which the neck would collapse when the > > tension was applied. These forces are equal and opposite to the applied > > force, resulting in an equilibrium situation in which there is no > > apparent change. > > > > Bending them around a corner doesn't make much difference to > > the force in magnitude (it decreases a little due to friction although > > depending on whether the tuned note is approached from above or below > > in pitch, it can actually be higher than the tension in the sounding > > part of the string.) So peg boxes are not bent back to reduce the > > force. > > > > ++Actually, bending a line, cord, rope, or string around corners > > produces a great deal of force in the form of friction, which always > > opposes motion. It is friction that keeps our pegs from rotating > > when set in a certain position (in theory). This is why we have > > capstans on boats. The more turns around the caps
Re: Bent peg box
Dear Michael,
Whereas some people think it's a problem, others see it as
an advantage. Like so many things, there are advantages
and disadvantages. How does a luthier compensate?
Assuming you did not like this effect, what kind of a repair
would the luthier do to fix it? Have you had this done and
is it expensive? (So far, I like mine the way it is, unless
someone can convince me that it is really a bad thing.)
I hope it lasts longer than I will. If it falls apart that fast
I've got problems. :)
It is not clear how my explanation sounds like the lute will
explode. This is a very gradual effect.
Were the old swan necks repaired or left in their deformed
state, assuming it is possible to tell this from looking at it?
Best Regards,
Marion
-Original Message-
From: Michael Thames <[EMAIL PROTECTED]>
Sent: Mar 14, 2005 8:39 PM
To: "Dr. Marion Ceruti" <[EMAIL PROTECTED]>,
Richard Corran <[EMAIL PROTECTED]>,
Lute List
Subject: Re: Bent peg box
++In reference to the deformation that occurs in swan-neck
lutes, we have a slightly non-equilibrium situation. The forces
are not exactly balanced and over a period of time the string
tension overcomes the rigidity of the neck. It will overpower the
neck in the place of least resistance, namely in the swan part of
the neck
Marion,
This isn't a problem. Of course the swan neck pegbox will bend
forward under initial tension. A lute maker will compensate for this, once
everything is adjusted it will last longer than you. You make it sound like
the whole thing will explode. Of course, Everything's impermanent, at some
point, but so far the swan neck lutes I've seen built 250 years ago are
fine.
Michael Thames
www.ThamesClassicalGuitars.com
- Original Message -
From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]>
To: "Richard Corran" <[EMAIL PROTECTED]>; "Lute List"
Sent: Monday, March 14, 2005 3:16 PM
Subject: Re: Bent peg box
> Dear Richard,
>
> Please see my comments below ++.
> ___
> There are a number of misunderstandings about the forces on a peg box.
>
> First of all the only force transmitted to the peg box comes from the
> strings.
>
> ++The other forces besides the transmited force are friction and the
> electrostatic forces inside the molecules that maintain rigidity in
> the neck, pegs, etc. without which the neck would collapse when the
> tension was applied. These forces are equal and opposite to the applied
> force, resulting in an equilibrium situation in which there is no
> apparent change.
>
> Bending them around a corner doesn't make much difference to
> the force in magnitude (it decreases a little due to friction although
> depending on whether the tuned note is approached from above or below
> in pitch, it can actually be higher than the tension in the sounding
> part of the string.) So peg boxes are not bent back to reduce the
> force.
>
> ++Actually, bending a line, cord, rope, or string around corners
> produces a great deal of force in the form of friction, which always
> opposes motion. It is friction that keeps our pegs from rotating
> when set in a certain position (in theory). This is why we have
> capstans on boats. The more turns around the capstan, the
> greater the friction and the better the advantage. Friction originates
> from the forces already resident in the material (which are balanced
> in the absence of a perturbation.)
>
> It does, of course, change the direction but so what?
>
> ++It redistributes the force. This change consititues the perturbation
> necessary to produce friction.
>
> Secondly the force on an individual peg is also practically identical
> whatever the angle of the peg box.
>
> ++The difference is the force distribution. The interesting part
> happens at the nut, not so much at the pegs, however much
> they may deform also over time.
>
> Again the peg will deform the same amount whether the peg box
> is bent back or not and this goes for immediate response of creep
> over a longer period of time.
>
> ++In reference to the deformation that occurs in swan-neck
> lutes, we have a slightly non-equilibrium situation. The forces
> are not exactly balanced and over a period of time the string
> tension overcomes the rigidity of the neck. It will overpower the
> neck in the place of least resistance, namely in the swan part of
> the neck. The longer the neck, the more pronounced the
> effect for the same initial tension. This is why it is easier to
> bend a 30-meter metal rod than it is to bend the a rod of the
> same material and diameter if it were 5 cm.
>
> The nature of tuned instruments is to keep the tension constant
> so the pitch is maintained.
>
> ++At equilibr
Re: Bent peg box
Yes, this is a reasonable theory. Certainly it moves the CG closer to the rose, as Richard has pointed out. The question is what is the main reason for the bend. Was it to alter the CG location or does it have something to do with stabilty and the CG change is just an added benefit? If my lutes are any indication, the CG theory would not be the main reason. My lutes are very light, even my baroque lute. However, I can see that this might be an issue with a larger lute with more mass. I once played an oud and it was not as light as a ren lute. cheers, Marion -Original Message- From: Vance Wood <[EMAIL PROTECTED]> Sent: Mar 14, 2005 4:31 PM To: lute list Subject: Re: Bent peg box I have a theory about the bent peg box that of course becomes moot with the advent of the Swan neck etc. The Lute is a very lightly constructed instrument, with the neck bent back the overall balance becomes more easily managed while playing. The neck assembly is after all the heaviest portion of the instrument. - Original Message - From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> To: "Howard Posner" <[EMAIL PROTECTED]> Cc: "Lute List" Sent: Monday, March 14, 2005 5:53 PM Subject: Re: Bent peg box > Dear Howard, > > Please see remarks below. > > Best regards, > Marion > > Dr. Marion Ceruti wrote: > > > Actually, bending a line, cord, rope, or string around corners > > produces a great deal of force in the form of friction, which always > > opposes motion. It is friction that keeps our pegs from rotating > > when set in a certain position (in theory). > > Indeed. The most noticeable effect of this is that when the pegbox is bent > back, the strings will stay in place on the nut without deep grooves (and > can be respaced at the nut with minimal alteration to the nut. > > ++Yes, I agree. This is caused by the increased tension on the nut. > > > If you increase the angle on the pegbox from zero > > to 90, which is the maximum, you will increase the friction on the nut > > according to the sine of the angle. This is why you will not see a > > pegbox set at an angle greater than 90 degrees. The function may > > be more complicated than a simple sine function, but this is the main > > effect. > > Perhaps, but there's a far simpler limit on the acuteness of the angle: > there has to be room for the left hand. > > +++Yes, I thought of that aspect after I sent the email. Even if you > were to have a box bent back further than 90 degrees to the point > where it were situated almost parallel to the neck in the opposite direction, > you could still reach around under it with your left hand to grab the neck > but it would be annoying to have to play that way. In summary, there are > multiple reasons for not going past 90 degrees. > > Howard Posmer > > > > To get on or off this list see list information at > http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html > > >
Re: Bent peg box
>I have a theory about the bent peg box that of >course .becomes moot with the >advent of the Swan neck etc. The Lute is a very lightly >constructed >instrument, with the neck bent back the overall balance >becomes more easily >managed while playing. The neck assembly is after all >the heaviest portion >of the instrument Vance, Are you sure your holding it right? Michael Thames www.ThamesClassicalGuitars.com - Original Message - From: "Vance Wood" <[EMAIL PROTECTED]> To: "lute list" Sent: Monday, March 14, 2005 5:31 PM Subject: Re: Bent peg box > I have a theory about the bent peg box that of course becomes moot with the > advent of the Swan neck etc. The Lute is a very lightly constructed > instrument, with the neck bent back the overall balance becomes more easily > managed while playing. The neck assembly is after all the heaviest portion > of the instrument. > - Original Message - > From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> > To: "Howard Posner" <[EMAIL PROTECTED]> > Cc: "Lute List" > Sent: Monday, March 14, 2005 5:53 PM > Subject: Re: Bent peg box > > > > Dear Howard, > > > > Please see remarks below. > > > > Best regards, > > Marion > > > > Dr. Marion Ceruti wrote: > > > > > Actually, bending a line, cord, rope, or string around corners > > > produces a great deal of force in the form of friction, which always > > > opposes motion. It is friction that keeps our pegs from rotating > > > when set in a certain position (in theory). > > > > Indeed. The most noticeable effect of this is that when the pegbox is > bent > > back, the strings will stay in place on the nut without deep grooves (and > > can be respaced at the nut with minimal alteration to the nut. > > > > ++Yes, I agree. This is caused by the increased tension on the nut. > > > > > If you increase the angle on the pegbox from zero > > > to 90, which is the maximum, you will increase the friction on the nut > > > according to the sine of the angle. This is why you will not see a > > > pegbox set at an angle greater than 90 degrees. The function may > > > be more complicated than a simple sine function, but this is the main > > > effect. > > > > Perhaps, but there's a far simpler limit on the acuteness of the angle: > > there has to be room for the left hand. > > > > +++Yes, I thought of that aspect after I sent the email. Even if you > > were to have a box bent back further than 90 degrees to the point > > where it were situated almost parallel to the neck in the opposite > direction, > > you could still reach around under it with your left hand to grab the neck > > but it would be annoying to have to play that way. In summary, there are > > multiple reasons for not going past 90 degrees. > > > > Howard Posmer > > > > > > > > To get on or off this list see list information at > > http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html > > > > > > > > > >
Re: Bent peg box
++In reference to the deformation that occurs in swan-neck lutes, we have a slightly non-equilibrium situation. The forces are not exactly balanced and over a period of time the string tension overcomes the rigidity of the neck. It will overpower the neck in the place of least resistance, namely in the swan part of the neck Marion, This isn't a problem. Of course the swan neck pegbox will bend forward under initial tension. A lute maker will compensate for this, once everything is adjusted it will last longer than you. You make it sound like the whole thing will explode. Of course, Everything's impermanent, at some point, but so far the swan neck lutes I've seen built 250 years ago are fine. Michael Thames www.ThamesClassicalGuitars.com - Original Message - From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> To: "Richard Corran" <[EMAIL PROTECTED]>; "Lute List" Sent: Monday, March 14, 2005 3:16 PM Subject: Re: Bent peg box > Dear Richard, > > Please see my comments below ++. > ___ > There are a number of misunderstandings about the forces on a peg box. > > First of all the only force transmitted to the peg box comes from the > strings. > > ++The other forces besides the transmited force are friction and the > electrostatic forces inside the molecules that maintain rigidity in > the neck, pegs, etc. without which the neck would collapse when the > tension was applied. These forces are equal and opposite to the applied > force, resulting in an equilibrium situation in which there is no > apparent change. > > Bending them around a corner doesn't make much difference to > the force in magnitude (it decreases a little due to friction although > depending on whether the tuned note is approached from above or below > in pitch, it can actually be higher than the tension in the sounding > part of the string.) So peg boxes are not bent back to reduce the > force. > > ++Actually, bending a line, cord, rope, or string around corners > produces a great deal of force in the form of friction, which always > opposes motion. It is friction that keeps our pegs from rotating > when set in a certain position (in theory). This is why we have > capstans on boats. The more turns around the capstan, the > greater the friction and the better the advantage. Friction originates > from the forces already resident in the material (which are balanced > in the absence of a perturbation.) > > It does, of course, change the direction but so what? > > ++It redistributes the force. This change consititues the perturbation > necessary to produce friction. > > Secondly the force on an individual peg is also practically identical > whatever the angle of the peg box. > > ++The difference is the force distribution. The interesting part > happens at the nut, not so much at the pegs, however much > they may deform also over time. > > Again the peg will deform the same amount whether the peg box > is bent back or not and this goes for immediate response of creep > over a longer period of time. > > ++In reference to the deformation that occurs in swan-neck > lutes, we have a slightly non-equilibrium situation. The forces > are not exactly balanced and over a period of time the string > tension overcomes the rigidity of the neck. It will overpower the > neck in the place of least resistance, namely in the swan part of > the neck. The longer the neck, the more pronounced the > effect for the same initial tension. This is why it is easier to > bend a 30-meter metal rod than it is to bend the a rod of the > same material and diameter if it were 5 cm. > > The nature of tuned instruments is to keep the tension constant > so the pitch is maintained. > > ++At equilibrium when forces are balanced. > > Thirdly there is no mechanical advantage in a system with only one > "pulley" as the nut is supposed to be. If you hang a single pulley > from the ceiling, put in a rope and attach a weight, you have to pull > with a force equal to the weight (plus a little for friction perhaps) > in order to lift the weight. To get a mechanical advantage you must > increase the number of pulleys. This clearly doesn't happen on lutes. > > ++Maybe a pulley is not the best analogy because in a pulley, you > have a rotating part that is designed to reduce friction, and friction > is important to the function of lutes. > (If one pulley alone produces 0 mechanical advantage and another > pulley alone also produces 0, how do you add or multiply them to get a > non-zero number? When I get the chance I will find the formula that > relates the number of pulleys to the force reduction, but this is not > related to lutes.) > &
Re: Bent peg box
< > Richard < So peg boxes are not bent back to reduce the >force. It does, of course, change the direction but so To: "Lute List" Sent: Monday, March 14, 2005 12:39 PM Subject: Re: Bent peg box > There are a number of misunderstandings about the forces on a peg box. > > First of all the only force transmitted to the peg box comes from the > strings. Bending them around a corner doesn't make much difference to > the force in magnitude (it decreases a little due to friction although > depending on whether the tuned note is approached from above or below > in pitch, it can actually be higher than the tension in the sounding > part of the string.) So peg boxes are not bent back to reduce the > force. It does, of course, change the direction but so what? > > Secondly the force on an individual peg is also practically identical > whatever the angle of the peg box. Again the peg will deform the same > amount whether the peg box is bent back or not and this goes for > immediate response of creep over a longer period of time. The nature > of tuned instruments is to keep the tension constant so the pitch is > maintained. > > Thirdly there is no mechanical advantage in a system with only one > "pulley" as the nut is supposed to be. If you hang a single pulley > from the ceiling, put in a rope and attach a weight, you have to pull > with a force equal to the weight (plus a little for friction perhaps) > in order to lift the weight. To get a mechanical advantage you must > increase the number of pulleys. This clearly doesn't happen on lutes. > > Fourthly since the forces arise from the strings on both the bridge and > nut, whether the peg box is bent back or not has no effect on how the > action changes over time unless the strings simply don't touch the nut. >This in unlikely. The change in action over time is associated with > the set up of the lute, the choice of materials, and the pitch to which > it's tuned together with the strings. Getting a combination of these > less than optimum is likely to lead to problems. > > I conclude that the angled peg box has two advantages: firstly it helps > to keep the centre of mass of the lute nearer the rose thus making the > lute easier to hold and secondly it looks more balanced. Of course > the latter is in the eye of the beholder. > > Sorry to sound so pompous. Put it down to my being a mechanical > engineer. > > > Richard Corran > > > > To get on or off this list see list information at > http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html >
Re: Bent peg box
True, but of course they should have bent the pegbox ninety degrees in the other direction and made it even longer. Then you could hang a little weight on the end of the pegbox and it would kick the lower rim of the lute in towards you, instead of flipping it out.Would have saved generations of lute players from resorting to straps, bits of string, suede pads, edges of table tops and pinky fingers pressing on the top in order to hold the damn things. David Cameron >I have a theory about the bent peg box that of course becomes moot with the >advent of the Swan neck etc. The Lute is a very lightly constructed >instrument, with the neck bent back the overall balance becomes more easily >managed while playing. The neck assembly is after all the heaviest portion >of the instrument. >- Original Message - >From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> >To: "Howard Posner" <[EMAIL PROTECTED]> >Cc: "Lute List" >Sent: Monday, March 14, 2005 5:53 PM >Subject: Re: Bent peg box > > >> Dear Howard, >> >> Please see remarks below. >> >> Best regards, >> Marion >> >> Dr. Marion Ceruti wrote: >> >> > Actually, bending a line, cord, rope, or string around corners >> > produces a great deal of force in the form of friction, which always >> > opposes motion. It is friction that keeps our pegs from rotating >> > when set in a certain position (in theory). >> >> Indeed. The most noticeable effect of this is that when the pegbox is >bent >> back, the strings will stay in place on the nut without deep grooves (and >> can be respaced at the nut with minimal alteration to the nut. >> >> ++Yes, I agree. This is caused by the increased tension on the nut. >> >> > If you increase the angle on the pegbox from zero >> > to 90, which is the maximum, you will increase the friction on the nut >> > according to the sine of the angle. This is why you will not see a >> > pegbox set at an angle greater than 90 degrees. The function may >> > be more complicated than a simple sine function, but this is the main >> > effect. >> >> Perhaps, but there's a far simpler limit on the acuteness of the angle: >> there has to be room for the left hand. >> >> +++Yes, I thought of that aspect after I sent the email. Even if you >> were to have a box bent back further than 90 degrees to the point >> where it were situated almost parallel to the neck in the opposite >direction, >> you could still reach around under it with your left hand to grab the neck >> but it would be annoying to have to play that way. In summary, there are >> multiple reasons for not going past 90 degrees. >> >> Howard Posmer >> >> >> >> To get on or off this list see list information at >> http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html >> >> >> > > > >
Re: Bent peg box
I have a theory about the bent peg box that of course becomes moot with the advent of the Swan neck etc. The Lute is a very lightly constructed instrument, with the neck bent back the overall balance becomes more easily managed while playing. The neck assembly is after all the heaviest portion of the instrument. - Original Message - From: "Dr. Marion Ceruti" <[EMAIL PROTECTED]> To: "Howard Posner" <[EMAIL PROTECTED]> Cc: "Lute List" Sent: Monday, March 14, 2005 5:53 PM Subject: Re: Bent peg box > Dear Howard, > > Please see remarks below. > > Best regards, > Marion > > Dr. Marion Ceruti wrote: > > > Actually, bending a line, cord, rope, or string around corners > > produces a great deal of force in the form of friction, which always > > opposes motion. It is friction that keeps our pegs from rotating > > when set in a certain position (in theory). > > Indeed. The most noticeable effect of this is that when the pegbox is bent > back, the strings will stay in place on the nut without deep grooves (and > can be respaced at the nut with minimal alteration to the nut. > > ++Yes, I agree. This is caused by the increased tension on the nut. > > > If you increase the angle on the pegbox from zero > > to 90, which is the maximum, you will increase the friction on the nut > > according to the sine of the angle. This is why you will not see a > > pegbox set at an angle greater than 90 degrees. The function may > > be more complicated than a simple sine function, but this is the main > > effect. > > Perhaps, but there's a far simpler limit on the acuteness of the angle: > there has to be room for the left hand. > > +++Yes, I thought of that aspect after I sent the email. Even if you > were to have a box bent back further than 90 degrees to the point > where it were situated almost parallel to the neck in the opposite direction, > you could still reach around under it with your left hand to grab the neck > but it would be annoying to have to play that way. In summary, there are > multiple reasons for not going past 90 degrees. > > Howard Posmer > > > > To get on or off this list see list information at > http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html > > >
Re: Bent peg box
Dear Howard, Please see remarks below. Best regards, Marion Dr. Marion Ceruti wrote: > Actually, bending a line, cord, rope, or string around corners > produces a great deal of force in the form of friction, which always > opposes motion. It is friction that keeps our pegs from rotating > when set in a certain position (in theory). Indeed. The most noticeable effect of this is that when the pegbox is bent back, the strings will stay in place on the nut without deep grooves (and can be respaced at the nut with minimal alteration to the nut. ++Yes, I agree. This is caused by the increased tension on the nut. > If you increase the angle on the pegbox from zero > to 90, which is the maximum, you will increase the friction on the nut > according to the sine of the angle. This is why you will not see a > pegbox set at an angle greater than 90 degrees. The function may > be more complicated than a simple sine function, but this is the main > effect. Perhaps, but there's a far simpler limit on the acuteness of the angle: there has to be room for the left hand. +++Yes, I thought of that aspect after I sent the email. Even if you were to have a box bent back further than 90 degrees to the point where it were situated almost parallel to the neck in the opposite direction, you could still reach around under it with your left hand to grab the neck but it would be annoying to have to play that way. In summary, there are multiple reasons for not going past 90 degrees. Howard Posmer To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
Re: Bent peg box
Dr. Marion Ceruti wrote: > Actually, bending a line, cord, rope, or string around corners > produces a great deal of force in the form of friction, which always > opposes motion. It is friction that keeps our pegs from rotating > when set in a certain position (in theory). Indeed. The most noticeable effect of this is that when the pegbox is bent back, the strings will stay in place on the nut without deep grooves (and can be respaced at the nut with minimal alteration to the nut. > If you increase the angle on the pegbox from zero > to 90, which is the maximum, you will increase the friction on the nut > according to the sine of the angle. This is why you will not see a > pegbox set at an angle greater than 90 degrees. The function may > be more complicated than a simple sine function, but this is the main > effect. Perhaps, but there's a far simpler limit on the acuteness of the angle: there has to be room for the left hand. Howard Posmer To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
Re: Bent peg box
Dear Richard, Please see my comments below ++. ___ There are a number of misunderstandings about the forces on a peg box. First of all the only force transmitted to the peg box comes from the strings. ++The other forces besides the transmited force are friction and the electrostatic forces inside the molecules that maintain rigidity in the neck, pegs, etc. without which the neck would collapse when the tension was applied. These forces are equal and opposite to the applied force, resulting in an equilibrium situation in which there is no apparent change. Bending them around a corner doesn't make much difference to the force in magnitude (it decreases a little due to friction although depending on whether the tuned note is approached from above or below in pitch, it can actually be higher than the tension in the sounding part of the string.) So peg boxes are not bent back to reduce the force. ++Actually, bending a line, cord, rope, or string around corners produces a great deal of force in the form of friction, which always opposes motion. It is friction that keeps our pegs from rotating when set in a certain position (in theory). This is why we have capstans on boats. The more turns around the capstan, the greater the friction and the better the advantage. Friction originates from the forces already resident in the material (which are balanced in the absence of a perturbation.) It does, of course, change the direction but so what? ++It redistributes the force. This change consititues the perturbation necessary to produce friction. Secondly the force on an individual peg is also practically identical whatever the angle of the peg box. ++The difference is the force distribution. The interesting part happens at the nut, not so much at the pegs, however much they may deform also over time. Again the peg will deform the same amount whether the peg box is bent back or not and this goes for immediate response of creep over a longer period of time. ++In reference to the deformation that occurs in swan-neck lutes, we have a slightly non-equilibrium situation. The forces are not exactly balanced and over a period of time the string tension overcomes the rigidity of the neck. It will overpower the neck in the place of least resistance, namely in the swan part of the neck. The longer the neck, the more pronounced the effect for the same initial tension. This is why it is easier to bend a 30-meter metal rod than it is to bend the a rod of the same material and diameter if it were 5 cm. The nature of tuned instruments is to keep the tension constant so the pitch is maintained. ++At equilibrium when forces are balanced. Thirdly there is no mechanical advantage in a system with only one "pulley" as the nut is supposed to be. If you hang a single pulley from the ceiling, put in a rope and attach a weight, you have to pull with a force equal to the weight (plus a little for friction perhaps) in order to lift the weight. To get a mechanical advantage you must increase the number of pulleys. This clearly doesn't happen on lutes. ++Maybe a pulley is not the best analogy because in a pulley, you have a rotating part that is designed to reduce friction, and friction is important to the function of lutes. (If one pulley alone produces 0 mechanical advantage and another pulley alone also produces 0, how do you add or multiply them to get a non-zero number? When I get the chance I will find the formula that relates the number of pulleys to the force reduction, but this is not related to lutes.) Fourthly since the forces arise from the strings on both the bridge and nut, whether the peg box is bent back or not has no effect on how the action changes over time unless the strings simply don't touch the nut. ++The action increases when the weakest part of the swan neck deforms in the direction to decrease the tension. The neck is not at equilibrium or nothing would ever move. This in unlikely. The change in action over time is associated with the set up of the lute, the choice of materials, and the pitch to which it's tuned together with the strings. Getting a combination of these less than optimum is likely to lead to problems. ++The set up or geometry of the lute is important. The bend in the pegbox keeps all strings at the same height at the nut, even if the pegbox bends from, say 90 degrees to 60 degrees. However, a 30- degree bend in a swan neck would produce a major change in action. The choice of materials relates to the composition of the parts, again originating in the differences between molecules. Different molecules have different intermolecular forces, which give rise to different tensile strengths and differernt frictional characteristics. I conclude that the angled peg box has two advantages: firstly it helps to keep the centre of mass of the lute nearer the rose thus making the lute easier to hold and secondly it looks more balanced. Of c
Re: Bent peg box
There are a number of misunderstandings about the forces on a peg box. First of all the only force transmitted to the peg box comes from the strings. Bending them around a corner doesn't make much difference to the force in magnitude (it decreases a little due to friction although depending on whether the tuned note is approached from above or below in pitch, it can actually be higher than the tension in the sounding part of the string.) So peg boxes are not bent back to reduce the force. It does, of course, change the direction but so what? Secondly the force on an individual peg is also practically identical whatever the angle of the peg box. Again the peg will deform the same amount whether the peg box is bent back or not and this goes for immediate response of creep over a longer period of time. The nature of tuned instruments is to keep the tension constant so the pitch is maintained. Thirdly there is no mechanical advantage in a system with only one "pulley" as the nut is supposed to be. If you hang a single pulley from the ceiling, put in a rope and attach a weight, you have to pull with a force equal to the weight (plus a little for friction perhaps) in order to lift the weight. To get a mechanical advantage you must increase the number of pulleys. This clearly doesn't happen on lutes. Fourthly since the forces arise from the strings on both the bridge and nut, whether the peg box is bent back or not has no effect on how the action changes over time unless the strings simply don't touch the nut. This in unlikely. The change in action over time is associated with the set up of the lute, the choice of materials, and the pitch to which it's tuned together with the strings. Getting a combination of these less than optimum is likely to lead to problems. I conclude that the angled peg box has two advantages: firstly it helps to keep the centre of mass of the lute nearer the rose thus making the lute easier to hold and secondly it looks more balanced. Of course the latter is in the eye of the beholder. Sorry to sound so pompous. Put it down to my being a mechanical engineer. Richard Corran To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
