Stringing, Tuning, Intonation and Witnesses

[Daftom]

Excuse my persistance on this rather inconsequential question...

it's actually the opposite problem, the A in particular has too little angle, you have to wind it all the way down or the string jumps around in the slot.

the E angle is usually fine.

...but you mean that even if you wind the A string down all the way (and it sounds fine), it would still be preferable to have an even bigger break angle, if that were possible? I believed that as long as the open string sounds good, the smaller angle the better. Not that it'd make a big difference -- but it'd facilitate fretting somewhat (and improve your intonation by an inaudible margin).

 

[walterw]

I believed that as long as the open string sounds good, the smaller angle the better. Not that it'd make a big difference -- but it'd facilitate fretting somewhat (and improve your intonation by an inaudible margin).

the angle behind the nut?

i don't see that influencing either of those things once you've set the witness point properly, so that the string is launching in a dead-straight line in both directions off the nut slot.

the problem with "too steep" is just that the string drags in the slot more, leading to tuning problems; the regular fender E, D and G angles are fine, the A is barely steep enough as long as you use lots of wraps.

 

[sissy kathy]

"Seating" is likely a better term for what "stretching" is supposed to accomplish.

I find I need to do very little other than set the witness points at the ends. I hold the wrap on the tuning post very tight while winding it up, also. Might be a tiny bit of retuning initially, but not much.

A string will return to it's original length (and tension) as long as it is not stretched beyond it's elastic limit. Any mild stretching that's done within this limit should have no effect on the string. So while it doesn't hurt anything (any more than bending a note does), it doesn't do anything either, aside from seating it better.

Stretching a string will only make a difference in the string if you exceed it's elastic limit, and at that point you will have likely damaged it.

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That is incorrect. Any stretching of metal causes the metal to fatigue; eventually to the point of failure. A fine example of this is in compressed gases. I'll use your home gas barbeque as an example. If you look at your gas tank, (cylinder) there is a date stamped into it at the upper end of the cylinder. That date isn't a date of manufacture, but rather a date of certification. It indicates that the tank was pressure tested on that date, the dimensions were noted before testing and the tank was then pressurized and noted a second time; it was then depressurized and measured yet again. The pressurized dimensions must not exceed tolerance, which is based in the initial (pre-pressurized) dimensions. Further, after depressurization. the tank must return to an acceptable tolerance, again that is based on the pre-pressurized dimensions. None of those dimension will be identical. Re certification has to be done every five years. Now, the reason for the recertification is, METAL FATIGUE. If you're a heavy user and fill you cylinder four or five times a year, it will receive a lot more wear than one that is filled once a year. This different rate of usage is why the tanks have to be periodically retested.

 

[walterw]

Re certification has to be done every five years. Now, the reason for the recertification is, METAL FATIGUE. If you're a heavy user and fill you cylinder four or five times a year, it will receive a lot more wear than one that is filled once a year.

what are those tanks made of?

with springy steel strings, as i understand it the metal fatigue thing is a matter of the "elastic limit"; stretch or bend a string below this limit and it springs right back with no deformation and no wear, the molecules go right back where they were. it's only when you force the metal past that limit (say, by bending it tightly around a tuning key post) that it deforms and won't go back.

other metals apparently don't work this way, any movement or bending will eventually lead to failure.

 

[sissy kathy]

what are those tanks made of?

with springy steel strings, as i understand it the metal fatigue thing is a matter of the "elastic limit"; stretch or bend a string below this limit and it springs right back with no deformation and no wear, the molecules go right back where they were. it's only when you force the metal past that limit (say, by bending it tightly around a tuning key post) that it deforms and won't go back.

other metals apparently don't work this way, any movement or bending will eventually lead to failure.

IDK, I wasn't involved in the manufacturing process. of for that matter in the certification process. I was a certified hazardous materials handling specialist, and as such was introduced to the rigors of tank testing.

 

[megafiddle]

That is incorrect. Any stretching of metal causes the metal to fatigue; eventually to the point of failure...

I'm sure you're correct about the propane tanks. I am also pretty sure that they are not constructed with spring steel.

Once a string is brought up to pitch, it will pretty much remain there, barring damage, corrosion, or abuse. If any stretching caused fatigue or an inability to recover from strain, wouldn't the string stretch and lose pitch continuously?

Also, consider the various types of mearuring instruments (scales, gauges, torque wrenches, etc) that rely on springs for their measurement mechanism. The good quality ones always return to zero and retain calibration.

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[sissy kathy]

I'm sure you're correct about the propane tanks. I am also pretty sure that they are not constructed with spring steel.

Once a string is brought up to pitch, it will pretty much remain there, barring damage, corrosion, or abuse. If any stretching caused fatigue or an inability to recover from strain, wouldn't the string stretch and lose pitch continuously?

Also, consider the various types of mearuring instruments (scales, gauges, torque wrenches, etc) that rely on springs for their measurement mechanism. The good quality ones always return to zero and retain calibration.

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All metals, save mercury, are subject to metal fatigue, even springs. The risk of failure can be reduced by over specing the sizes and strength of the material, but ANY cyclic load reduces the strength of metal and causes fatigue. Even mercury would be subject to metal fatigue if you managed to have a temperture which was cold enough to manufacture in.

 

[JustForSport]

what are those tanks made of?

High tensile steel, same as string cores, maybe a little different alloy, because that's what steel is- an alloy.
But the same testing for the same reasons (as noted by @sissy kathy) goes onto dive tanks- made of high tensile aluminum.

 

[JustForSport]

A spring may be made of high tensile alloy, but not so hard that it is brittle. It is 'tempered' thru a heat process that allows it to retain maximum 'return-ability' when used as designed, for a sustainable period. Exceeding that that design spec can cause deformation of the spring and it will not return to its previous form. Some, however can be heat-treated again and they will then return to their previous shape.

 

[megafiddle]

The vapor pressure of propane is about 140 psi at 25 degrees C.

SCUBA tanks are about 3000 - 4000 psi.

No comparison.

Propane tanks are also now made from fiberglass/epoxy.

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[sissy kathy]

The vapor pressure of propane is about 140 psi at 25 degrees C.

SCUBA tanks are about 3000 - 4000 psi.

No comparison.

Propane tanks are also now made from fiberglass/epoxy.

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The principal is the same, you can't suspend physics.

 

[megafiddle]

The principal is the same, you can't suspend physics.

Yes, but which principle?

I am only saying that the string needn't be stretched additionally to retain it's integrety. It will simply stretch to achieve the required pitch and then stay there (unless it slips or takes up some type of slack).

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[Turnaround]

If you want to discuss the properties of steel, please bring it back to the topic at hand - stringing, tuning intonation and witnesses. I think we are losing the thread.

 

[JustForSport]

Point being-
String cores are made from high tensile steel, not spring steel, and they are designed to work within a narrow tolerance of max tension. They don't just stretch way out there and return w/o damage- not designed for that. There is an allowance/tolerance for over tensioning w/in that designed tension spec- maybe 15% or so, depending on the manufacturer (I remember reading something from DR about their chosen amount, and a reference to typical piano string tolerance). This is for breakage prevention as well as longevity of the product. Slight tension increases to allow for playing deformation (plucking harder, bends, etc) are w/in the design spec for the core tension.
Any tensions above the designed tension limit, even in the tolerance range, will decrease the life of the product.

'Stretching' the strings too much at installation while settling the wraps on the post contributes to the accumulated fatigue over the life of the string. A little pulling to settle the wraps harms nothing. It's not 'what's done', it's 'how it's done'.

To keep the string at constant pitch (since it is not very stretchy) the string needs to go straight from each contact point to the next: anchor to saddle, saddle to nut, nut to side of tuner post.
'Lazy' curves over these points allows too much range of tension to keep the string playing at pitch.

 

[walterw]

If you want to discuss the properties of steel, please bring it back to the topic at hand - stringing, tuning intonation and witnesses. I think we are losing the thread.

i think this is good, we're trying to drill down into what "stretching the strings" really means.

the term i was looking for was "fatigue limit" (wiki), past which damage occurs.

like i said, apparently with certain steels any flexing below this limit essentially causes no damage and can be repeated essentially forever, while with other metals this isn't the case.

i'm guessing that with things like @sissy kathy's example of her experience with high-pressure tanks holding dangerous substances, since failure means Bad Things Will Happen, even if it's theoretically safe the procedure is to not take chances.

if the tank safety testing is by measuring the changes in dimensions of these tanks after use, then that means they by definition are not springing back 100% to their original shape and so are getting fatigued at least a little bit. maybe that means for even the "right" kind of steel, making it thick enough to do the job means that even the slightest deformation is still beyond the fatigue limit.

 

[Turnaround]

i think this is good, we're trying to drill down into what "stretching the strings" really means.

the term i was looking for was "fatigue limit" (wiki), past which damage occurs.

like i said, apparently with certain steels any flexing below this limit essentially causes no damage and can be repeated essentially forever, while with other metals this isn't the case.

i'm guessing that with things like @sissy kathy's example of her experience with high-pressure tanks holding dangerous substances, since failure means Bad Things Will Happen, even if it's theoretically safe the procedure is to not take chances.

if the tank safety testing is by measuring the changes in dimensions of these tanks after use, then that means they by definition are not springing back 100% to their original shape and so are getting fatigued at least a little bit. maybe that means for even the "right" kind of steel, making it thick enough to do the job means that even the slightest deformation is still beyond the fatigue limit.

I still don't see how this connects with problems of tuning or intonation. Is the "fatigue limit" of bass stings a factor?

 

[TheIndieKid]

Reviving a dead thread. Is there a general consesnsus on how long you should cut Strings for different tuners?

 

[Turnaround]

Reviving a dead thread. Is there a general consesnsus on how long you should cut Strings for different tuners?

Consensus? No. Opinions - plenty. I prefer fewer wraps than many suggest. The more string there is on the post, the more there is to hold slack (for a while). And when that slack gets worked out, your string goes flat.

One common view is that you should have enough wraps on the post so that the string winds down to the very bottom of the post. That ensures a good break angle at the nut. However, you can achieve a good break angle in most cases without a lot of windings. You just need to force the windings to the bottom of the post. Those tuners with tapered posts will force the string to the bottom with as little as one winding on the post.

OTOH, the string is held in position on the post by friction alone (unless you have string-locking tuners). If you have too little winding on the post, there may not be enough surface friction to keep the string from slipping. So conventional wisdom says you should have 2 to 3 complete wraps on the post to ensure there will be no slippage.

But how do you ensure that you will get 2 to 3 windings on the post when you are about to cut your new strings? Should you cut the string 4 inches past the post? Four fingers past the post? Well, it depends on the post diameter. 4 inches of string are going to give a lot more wraps on a skinny post than a fat one. So, next time you are about to do a string change, do this. Take a string off - remove it from the tuner and the bridge. Cut it at a point where you have a length of straight string to work with. Stick the end of the string in the hole in the centre of the tuner. Bend it at right angles through the slot in the tuner. Bend it again tight against the tuner post as if you were going to wind it in the usual way. Wrap the string tightly around the post 2 or 3 times (take your pick) and mark the string at that last wind. Take the string off and straighten the windings. Measure the distance from the end of the string to the mark you made. Now you know where to cut the new string beyond the post to ensure your choice of windings.

There is neat trick you can do using this information to have all the tuning machine ears line up in the same plane (or close) when the bass is in tune. See if you can figure it out.

 

[sissy kathy]

... or math.

 

[Turnaround]

... or math.

Yes - if you know the diameter of the tuning post, you can work out the length of string you need. But if the post is tapered, remember to account for the changing diameter along the length of the post. And if it's that nasty capstan shape (hourglass) it gets a bit more complicated.