| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
05 Sep 2005 06:41:26 AM |
| Object: |
A Classical Mechanics Question |
(this message is best readable in monospaced font)
A classical guitar is essentially made of a box with a board attached
(glued) to it using a reinforcing heel:
fretboard box
+----------------------------+-+----------------------+
+----------------------------| | |
| | |
heel ---> | | |
+-| |
+----------------------+
A guitar in perfect condition maintains straight line between the
fretboard and the body (box). However, the strings attached at
(roughly) each end (the end of the fretboard and end of the box) do
exert significant force (~10Kg) which strive to pull the fretboard
upwards, which result in a concave-like form - if the guitar is not
properly maintained.
The question now is what "properly maintained" means:
Some say that the time in which the strings are stretched should be
minimized - that is, whenever not played, the strings should be
loosened, to minimize the time in which the glued joint is under
stress and "to let it rest".
Others say that this constant (daily) stretch-release cycle can
actually do more harm than good. They say that it is best to *always*
leave the strings tuned (i.e. stretched), which creates a "static
equilibrium" (whatever that means).
My question is: Which "camp" is right? Which approach will result in a
faster weakening of the joint between the fretboard and the box?
Thanks,
Daniel
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| User: "Andy Resnick" |
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| Title: Re: A Classical Mechanics Question |
07 Sep 2005 07:50:50 AM |
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wrote:
<snip>
The question now is what "properly maintained" means:
Some say that the time in which the strings are stretched should be
minimized - that is, whenever not played, the strings should be
loosened, to minimize the time in which the glued joint is under
stress and "to let it rest".
Others say that this constant (daily) stretch-release cycle can
actually do more harm than good. They say that it is best to *always*
leave the strings tuned (i.e. stretched), which creates a "static
equilibrium" (whatever that means).
My question is: Which "camp" is right? Which approach will result in a
faster weakening of the joint between the fretboard and the box?
Good question- I have heard the same debate in regards to drumheads
(marching drums especially), and I suspect there is also the same issue
in any stringed instrument: violins, for example. And then there are
mandolins- aren't those maintained at significantly higher tension than
guitars? I know thers is a more significant issue in regards to
seasonal changes in humidity, especially when the instrument is not
stored in a controlled environment (i.e. my drums in the basement).
One suspects that owners of primo violins and cellos have this issue
resolved to their satisfaction.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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| User: "Randy Poe" |
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| Title: Re: A Classical Mechanics Question |
07 Sep 2005 08:06:33 AM |
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Andy Resnick wrote:
danibe@my-deja.com wrote:
<snip>
The question now is what "properly maintained" means:
Some say that the time in which the strings are stretched should be
minimized - that is, whenever not played, the strings should be
loosened, to minimize the time in which the glued joint is under
stress and "to let it rest".
Others say that this constant (daily) stretch-release cycle can
actually do more harm than good. They say that it is best to *always*
leave the strings tuned (i.e. stretched), which creates a "static
equilibrium" (whatever that means).
My question is: Which "camp" is right? Which approach will result in a
faster weakening of the joint between the fretboard and the box?
Good question- I have heard the same debate in regards to drumheads
(marching drums especially), and I suspect there is also the same issue
in any stringed instrument: violins, for example.
Many years ago, I took violin lessons as a child.
I was taught to release the tension in the bow when
not playing, but there were no such instructions concerning
the violin itself.
- Randy
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| User: "PD" |
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| Title: Re: A Classical Mechanics Question |
06 Sep 2005 11:51:28 AM |
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wrote:
(this message is best readable in monospaced font)
A classical guitar is essentially made of a box with a board attached
(glued) to it using a reinforcing heel:
fretboard box
+----------------------------+-+----------------------+
+----------------------------| | |
| | |
heel ---> | | |
+-| |
+----------------------+
A guitar in perfect condition maintains straight line between the
fretboard and the body (box). However, the strings attached at
(roughly) each end (the end of the fretboard and end of the box) do
exert significant force (~10Kg) which strive to pull the fretboard
upwards, which result in a concave-like form - if the guitar is not
properly maintained.
The question now is what "properly maintained" means:
Some say that the time in which the strings are stretched should be
minimized - that is, whenever not played, the strings should be
loosened, to minimize the time in which the glued joint is under
stress and "to let it rest".
Others say that this constant (daily) stretch-release cycle can
actually do more harm than good. They say that it is best to *always*
leave the strings tuned (i.e. stretched), which creates a "static
equilibrium" (whatever that means).
My question is: Which "camp" is right? Which approach will result in a
faster weakening of the joint between the fretboard and the box?
Thanks,
Daniel
It's useful in this discussion to point out the difference between
elastic limit and elastic strength. As long as the tension in the wires
does not exceed the elastic limit, the neck behaves like a leaf spring
in the sense that all energy stored in the neck will come back out,
without any significant portion going into a permanent deformation of
the neck.
There IS a problem, however, if you put steel strings on a guitar
designed for nylon strings, because to get steel strings in the same
tune requires much more tension, and this tension is usually getting
close to the elastic limit of a classical or folk guitar. Then,
permanent deformation can occur.
PD
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| User: "AJW" |
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| Title: Re: A Classical Mechanics Question |
06 Sep 2005 03:49:40 PM |
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Gotta be careful here. Nylon strings undergo plastic deformation --
elastic 'creep' even under modest loads. The necks of the guitars I
owned work within what I'd call Hook's Law limits. Deformation of the
necks are small and as best I can tell, undergo full recovery with
string tension is relaxed.
I wish my playing was up to the standard of my talking!
Yeah, it's that bad.
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| User: "Henry Lemington-Wholeflavors" |
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| Title: Re: A Classical Mechanics Question |
05 Sep 2005 10:57:03 AM |
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wrote:
(this message is best readable in monospaced font)
A classical guitar is essentially made of a box with a board attached
(glued) to it using a reinforcing heel:
fretboard box
+----------------------------+-+----------------------+
+----------------------------| | |
| | |
heel ---> | | |
+-| |
+----------------------+
A guitar in perfect condition maintains straight line between the
fretboard and the body (box). However, the strings attached at
(roughly) each end (the end of the fretboard and end of the box) do
exert significant force (~10Kg) which strive to pull the fretboard
upwards, which result in a concave-like form - if the guitar is not
properly maintained.
The question now is what "properly maintained" means:
Some say that the time in which the strings are stretched should be
minimized - that is, whenever not played, the strings should be
loosened, to minimize the time in which the glued joint is under
stress and "to let it rest".
Others say that this constant (daily) stretch-release cycle can
actually do more harm than good. They say that it is best to *always*
leave the strings tuned (i.e. stretched), which creates a "static
equilibrium" (whatever that means).
My question is: Which "camp" is right? Which approach will result in a
faster weakening of the joint between the fretboard and the box?
In all my 15 years of playing various guitars, I have never heard of
this joint going.
I'm sure loosening the strings every time you've finished playing would
be a real pain, especially when you have to tune up again every time
you resume playing, and make sure it's at concert pitch, and I suspect
that that would lead to that joint going quicker. Constant cycles of
strain and relaxation, would be worse than just strain.
Incidentally, I like playing at a semi-tone below concert pitch, for
both acoustic and electric guitars. I find it has a nicer sound, but,
of course, it would be better for that joint also.
--
http://cherenkov-radiation.blogspot.com/
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| User: "AJW" |
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| Title: Re: A Classical Mechanics Question |
05 Sep 2005 03:00:29 PM |
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A half tone low is an interesting idea, but doesn't your ear complain
Romanza or Tattega's Alhambra sounds like it's a little less, well,
lively -- a little dull?
I have enough trouble with nylon strings undegoing plastic creep when I
keep them taut. Relaxing them and retightening them is something way
past anything I'd do. Is that a problem with steel strings, too? I'd
have guessed their tension is way below their elastic limit.
And isn't it fun typing with callouses on your left hand fingers and
nails long enough to click on the keys with your right?
.
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| User: "Henry Lemington-Wholeflavors" |
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| Title: Re: A Classical Mechanics Question |
06 Sep 2005 09:16:22 AM |
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AJW wrote:
A half tone low is an interesting idea, but doesn't your ear complain
Romanza or Tattega's Alhambra sounds like it's a little less, well,
lively -- a little dull?
I have enough trouble with nylon strings undegoing plastic creep when I
keep them taut. Relaxing them and retightening them is something way
past anything I'd do. Is that a problem with steel strings, too? I'd
have guessed their tension is way below their elastic limit.
Yeah, I find steel strings stay in-tune a lot longer than nylon ones.
And isn't it fun typing with callouses on your left hand fingers and
nails long enough to click on the keys with your right?
lol. I do have the callouses, but all my finger nails are very short -
I play classical music on the piano, but now I pretty much just use a
plec for playing the guitar. I have made brief forays into learning
classical guitar music in the past, though, and will again in the
future sometime.
--
http://cherenkov-radiation.blogspot.com/
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| User: "" |
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| Title: Re: A Classical Mechanics Question |
06 Sep 2005 08:12:56 PM |
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Henry, thank you too for your answer. You are correct in that loosening
the strings every time I have finised playing is a real pain. The
question however is not about convenience (at least for now), but
rather about the mechanical principle. I simply got curious (see my
longer answer to AJW).
You actually answered my question by saying that "constant cycles of
strain and relaxation, would be worse than just strain". I would be
glad to also understand why, since I have long lost my knowledge in
classical mechanics ("if you don't use you loose it"). Can you back
your claim by some scientific illustrations (I have no problem with
math)?
Thanks,
Daniel
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| User: "AJW" |
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| Title: Re: A Classical Mechanics Question |
05 Sep 2005 08:46:41 AM |
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Daniel, I don't think therre's much plastic 'creep' in the neck of my
guitar. I keep the strings taut.
There has to be some elastic bowing of the neck when the strings are
taut, of course, but for my case at least the string to fret distance
doesn't seem to change in a noticable way when I replace strings (I
remove all of them first, then add the new ones. There's lots of creep
in the strings, but you know that. It takes a long time before new
strings actually hold their pitch for the better part of a day..
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| User: "" |
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| Title: Re: A Classical Mechanics Question |
06 Sep 2005 08:04:33 PM |
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AJW, thanks for your reply. Your experience is similar to mine - I
can't really report any elastic bowing of the neck over a short period
of time. I certainly cannot report it when replacing strings, because I
have no easy way to measure the difference in the distance between the
strings and the fretboard (aka "action") when there are no strings. :-)
I was referring however to a *very* long term effect - 5 or more years.
I have certainly seen (inexpensive) classical guitars that lost their
straightness over the years.
The reason I resorted to asking this question on this newsgroup is my
recent confusion over the subject, after I purchased an expensive
($2,000) Flamenco guitar, and I was instructed by the maker to "loosen
the strings (3 turns or more) whenever not played".
This came to me as surprise since in my 27 years of playing classical
guitars, I have always maintained the strings tuned. Then again, those
guitars were always inexpensive ones (less than $200) and I was never
too happy with their "action".
Moreover, printed instructions I received with an Admira flamenco
guitar I purchased 2 years ago (~$300) clearly state that the when
replacing strings, they should be changed one at a time, while
maintaining the others tuned.
Confused by this discrepancy, I contacted the maker of my expensive
guitar via email, and he maintained his position. He explained that the
$300 Admira guitar is built differently and that they recommend keeping
the strings tuned only while replacing the strings, in order to bring
the guitar to tuning faster.
Me thinks: "What do I know about guitars? He is the expert. He is a
luthier. He must be saying that based on his many years of experience."
(he is a very reputable guitar maker in Spain and in the world).
I am confused however, since this disagrees with everything I have come
to know throught the years (even my guitar teacher scoffed at this
idea).
Is it possible that expensive guitars answer different physics laws
than inexpensive ones?
Thank you so much!
Daniel
AJW wrote:
Daniel, I don't think there's much plastic 'creep' in the neck of my
guitar. I keep the strings taut.
There has to be some elastic bowing of the neck when the strings are
taut, of course, but for my case at least the string to fret distance
doesn't seem to change in a noticable way when I replace strings (I
remove all of them first, then add the new ones. There's lots of creep
in the strings, but you know that. It takes a long time before new
strings actually hold their pitch for the better part of a day..
.
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| User: "AJW" |
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| Title: Re: A Classical Mechanics Question |
07 Sep 2005 12:34:23 AM |
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Actually, Dan, if you first replace an upper string and bring it into
tune and notice the action, you'll have a measure of the neck bowing as
you bring the other strings into complience. I haven't noticed a
difference as other strings are tightened.
I have no idea why the expensive guitar would act differently than a
$300 one. Is the neck physically thinner? My experence is like yours,
but I'd sure follow the advice of the manufacturer anyhow.
I do know if I relax the strings for a while and then retighten them
the tuning 'drifts' pretty fast, so I leave them concert tuned -- not
that they stay that way, of course -- when I'm done abusing the
instrument.
Here's the real question. I expect the action is a lot sweeter on your
expensive new guitar, but how does it sound?
.
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