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After a long, long time of not having a string break on me during tuning, it happened today. I was on the second pass through the treble section of an old and worn Kawai 500 when the bang happened. I looked and two strings had popped simultaneously. Wow. Two in one blow. Where do I pick up my certificate?

Gotta have one break every once in a while just to make sure you're paying attention.

I will NEVER get used to breaking a string. I jump, and let out a little squeal every time!!! LOL!

I was finishing up tuning the piano on a sound stage as the musicians were coming back in.

I was on the last few single bass strings when I heard it ...."Blam" it went. Well, you can imagine what went through my mind at that point... Of all the things to happen at that time of all times.

I looked at the strings .... Nothing broken!!!...quick glance around the rest of the strings... No, it definately sounded like a bass string...Couldn't have been anything else.

I looked up and saw the widest grin the face of one of the percussionists looking right at me. He had been clocking my rythms as I tuned and he hit something that sounded like a breaking bass string at the precise moment he knew I would sound the note. The relief must have showed on my face immediately and we shared a laugh in the space between us.

What skill on his part, to recreate every sound he ever heard and at the precise moment it it required (or not). I 'spose that's why he's doing that class of work.

How about having a consistent habit of putting a counterclockwise movement on a tuning pin first as preventative measure to breaking strings? It has always seemed to greatly cut down on the number of strings I have broken. However, I recall many years ago when tuning a Steinway Model L, I made the counterclockwise movement on a bichord string in the Bass, and BANG!

I spliced the string withe the remnant and it broke again! "Well", I thought, "I'll have to replace this string". I proceeded to the next string of that bichord, made a counterclockwise movement and it broke too! I did not try to splice it but went the long route of having both strings duplicated.

I can only think of one other instance where a counterclockwise movement cause a string to break. This topic, is of course, about breaking a string with a test blow. I hate that even worse than I do breaking a string with the tuning hammer!

Every so often at the Shout House, one will let go while I'm tuning. Most of the time, if I'm on that wire, I can hear it before it happens; the pitch starts heading south. Even when that happens, I still jump.

The vast majority of the plain wire breaks on those pianos are at the capo bar. Bad scale design, anyone?

You must be or have been a dirt bike rider. If you never crash, you're not riding hard enough.

It is not necessarily bad design. It is metal fatigue.

Well, there is that. I just find it interesting they almost all break in the same spot. There must be a reason beyond simply fatigue, or they would break wherever the wire was weakest; to the best of my knowledge, metal doesn't fatigue uniformly. I could be wrong...

I have some that break at the loops(recall these are single-strung). Those occur at a bend, so that makes sense.

You are correct in that fatigue doesn't happen uniformly. The material fatigue happens where the strings bend the most - at the termination, which is why they break there. (Breakage at the bridge pin is a result of the same thing)

They certtainly will break more where the strain ranges crom 65% to 80% (real value lessened 25% to compensate for the bends)than in the mediums or low mediums with a large security margin. top basses can be much constrained too.

I have yet to see one go at the bridge pin on one of these, out of hundreds of string breakages I've repaired on these pianos. Interesting...

Treble strings seem to break more at the capo bar, perhaps because this is close to the strike point. I have seen many bass strings that snapped during play, they often part at the bridge pin. This is usually a symptom of metal fatigue as a result of heavy playing with the gas pedal depressed.

Yes, metal fatigue is the reason why any string breaks. Just imagine the way a string waves up and down within an envelope between two pivot points: the agraffe (or capo bar) and the proximal bridge pin. The material is stressed more at these two points than anywhere else in the string length. If the hammer happens to strike the string when it is at its maximum point upwards and the metal is already weak, that is why and where it breaks.

I have seen many strings that have broken at he capo bar and agraffe but also a few at the bridge pin. I recall many years ago, two strings of the same wound string, bichord unison in a brand new studio vertical piano breaking at a very unusual place: between the distal bridge pin and the hitch pin loop, about half way.

One of them broke during a fist time in service tuning, so a new string was ordered and replaced. The piano was in a restaurant. Two days later, the pianist called and said the other string of that bichord had broken in the same place while the piano was being played! The dealer asked me why this had happened. I could think of only one possibility: the string winding person had used the string cutters to pull the wire off of the spool and managed to nick the wire in that spot.

Have you ever noticed that when a string breaks when turning the tuning pin, it always breaks right at the tuning pin? The reason for the breakage is that the segment between the tuning pin and the first termination point is overly stressed. The first termination point is offering enough resistance to create more tension than the wire can bear.

This is the reason for the recommendation to put a slight counterclockwise movement on a tuning pin before attempting to raise the pitch. That will serve to relieve that bond that has set up between the first termination point and the string. It won't always help, of course but it does seem to me to have prevented many a string from breaking for me, even during very large pitch raises on older pianos.

I also firmly believe in using an impact type technique over a slow pull type for the same reason. However, there are two points of view on that. If one wants to break a piece of material, whatever it may be, doesn't one use some kind of sudden force rather than a slow bend? Either would work at some point but a sudden "whack" would seem to do the trick better than a slow strain.

However, an impact type technique serves to move the entire length of the string better than a slow pull. The slow pull is more apt to overly stress the first segment of the string between the tuning pin and the first termination point.

When the string does break, it breaks right at the tuning pin because this is the place where the wire is being bent and it is the origin of the stress. So, even though the wire is bent at the first termination point as well, there is more stress at the tuning pin when attempting to raise the pitch, so that is where the string breaks and it does that each and every time it happens.

bronze and brass wire on harpsichords break when the tension is lessened, and at the tuning pin generally. Something related to the elasticity of the metal which is better under tension if I recall exactly.

My tech, who I believe is well known to many techs at PW(he has written a book on tuning and invented a popular tuning hammmer), told me he once broke around six strings on a Boesendorfer. I think he said they were later found to be defective.

If they where the big unichords wire from the extreme bass they where so much tense at some point they could break as soon as they age enough.

Also with bass strings playing with different "stretches" will often fatigue the metal enough. I had 2 bass stings broken during a radio show presenting Helene Grimaud, for her next concert , simply because a new tuner joined the pool a few weeks ago and was tuning most of the basses in 12:6 (very large stretch ). Others put the basses higher once, twice, and when it came to my turn, after having be felicitated by Mrs Grimaud who said "of your are a good tuner ! that is rare !) She begin to play and 2 bass strings broke at 10 minutes interval !

SO it is useless to be a good tuner ! in that situation I should have left the extra low basses or not raise them as much, may be (and I was tuning very quietly in those times)

I have always wondered. Aside from string fatigue. Has anyone ever noted at what point a string will break from overtension? That is to say if you are tuning an A for example. How high in pitch can you go before the string will break? A#? B?

Hello, the way you ask shows that you are not aware that the wire us constrained differently depending the octave and scale.

Before breaking the wire get in a poorer elasticy zone where it tones bad and does not hold pitch.
Then it get to "plasticity zone" where it simply deforms
Then it breaks

With time the wire hardens and it is less elastic (and produce more inharmonicity)

On most pianos C3 can be raised a full M3 without attaining the elasticity limit and c88 could break with a strong half step rise.

When tuning, the "overpull" is limited to the tension lessening that will occur because of the bridge and soundboard move (due to more stress applied to them) AND to the part necessary to bring back the tuning pin in its original more or less "torqued" position .
The "no torque" concept is not possible assuming the wire is yet providing 70 80 Kg force on one side of the pin, but mostly, when the note is banged a supplementary stress is attaining the pin, if it is in a neutral position it will tend to lower or to move a little under the wave impact coming from the string, so the contrary pin torque is a security and a lock for the tuning pin.

I see the note raising when tuning as a mean to put it at a position from which it will "land" to the wanted pitch naturally

I think a rough rule of thumb is about 300 cents before it snaps.