Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Temperament and tuning stability?

I heard that heat can be used to stabilize the wire, and that was the process used in Schimmel factory.

Due to the particular tone their pianos had I always have suspected a particular treatment to the new wire, possibly the huge overstretching advocated by K.Fenner, as the once time I used that method, the wire had a very different tone, very clear, less inharmonic probably, but sounded a little too much "white metal" to my liking.

In any case my dear colleagues in the factories will have some questions from me (they love me

Here's the link from the last thread:
http://www.physicsforums.com/archive/index.php/t-230039.html
(I haven't read through it yet.)

Thanks , that is the same I find..

I edited my last post, here is waht I wrote :
It seem to appear that creep factor is negligible, in regard of pitch lowering, even if real (I call it the "hardening" of the wire)

In any case then, the main effect of stretch may come from the bends and turns who really "stretch" the wire.

The metal may also change its organization when put under stress.

I noticed that Paulello wire is stabilized very soon, if compared to Roslau.

Difficult to find studies on the subject. Discussions, yes, but searches are not so evident.

does a piano wire deforms

"creep" seem to be related to stress under high temperatures, does not seem to apply well for piano wire.

Then, one technique given to me for massaging new wire is to use a wooden T shaped piece than the stringers can push on while standing (the piano is then vertical).
The plain wire are then massaged up and down, and the job have beenn "done well if the strings are warm" afterthat (traditional method that may have been used in some piano factories)

Warmness... is it a sufficient level of warmness to modify something in the string metal itself ?

When looking at it , the piano wire is a complicated product. Dan posted us a link to an analysis of the strain resistance obtained while drawing, and saying higher strain could be attained, the metallurgy seem to be very complicated...

I am not saying creep does not exist. I wonder, though, if it actually significant for pianos owners and tuners.

Personally I no longer believe that stings "stretch" enough to flatten by 1/2 step. My experience and discussions with others have persuaded me that it is the new string slowly tightening around bends that appears like "stretch". This is corroborated by the unchallenged observation that softer wires such as Pure Sound and Paulello stabilize much faster than the harder, stiffer wires such as Mapes and Röslau. Itmakes sense that this would be the case.

I agree that a definitive and absolute scientific answer would settle the debate once and for all.

I suppose a fairly simple experiment could provide proof: bring a new string up to tension, measure and mark off a certain portion of the string within the speaking section. Then tune and re-tune for two years. Measure again.

Until someone does this or has other, more scientific proof, I will remain a convert from the "stretch belief" to the "compliance belief".

When I replace a string, I go through a regimen of coil tightening and such. The string is generally pretty stable within a month or two. But there are residual effects that last a while longer, which is probably due to creep.

Jurgen,

Which Paullelo, as there are 4 tensile stengths. The type "M" is in my understanding the equivalent of modern Roslau. Are you referring only to the softer type "O", "1" and "2" or the "M" as well?

Jim Ialeggio

As stated, I was speaking of the wires which are softer than M. & R.

http://www.astm.org/DIGITAL_LIBRARY/JOURNALS/TESTEVAL/PAGES/JTE11908J.htm

This is a scientific paper that states that there is relaxation during the beginning and less as time passes. I got this from the physics forum that a link was posted for. Kudos for that.

I went to Mapes a while back because I did not have any 15-1/2 gauge left and when the head stringing department guy came out I told him what I wanted and he asked if I had the old string. I thought heh I guess he doesn't think I can use a micrometer. Well he pointed out that the string was a little smaller than what a new one would be but that was normal on an old piano. Which it was off a 1920's Steinway. I will be asking more questions next time I go there.

Argh. It really amazes me that modern piano wire has been around for over a hundred years and there still seems to be so much we don't know about piano wire. I am not sure if the info is out there just spread so thinly and kept hush by manufacturers or it's just NOT known.

Well I think that properly bending the string around hitch pins bridges etc. is very important and will help a lot with the initial slackening but there is some stretch in the actual wire.


Well there is my two cents...If I put in a few more here and there I might just end up in EBVT!

I have seen that abstract, but it use high temperature. Is it used to simulate time ?

It sound coherent that some elongation occurs in time, anyway it is what is seen when we dismount old wire, but it may be because the elasticity limit have been reach at some point, due to the age of the wire...

I hope we will have more precise answers.

Anyway, the stretch of the wire is an important parameter when it comes to the design of a new scale, as was said to me by a reputable piano builder from an old brand. He stated that this parameter was allowing less pitch changes with the seasonal variations , i.e. the wire will change less in pitch.

I dont get if the wire elasticity is changing much with the relation to BS limit, but I can imagine that a more elastic wire could change less in pitch under more tension, than a less resilient one.

Seem that even the M quality, which is a little more resistive than Roslau, is at the same time softer.

The speed at which the drawing is conducted was said to me having a somewhat large influence on the softness of the wire.

But in the end the wire is not an homogenous material, the core is harder than the center (other terms may certainly apply)

This is the abstract from the above link:

"Stress relaxation data were obtained in tension tests using the vibrating string technique (measuring the resonance frequency) in spring steel wire of ASTM Grade A 228 (also known as music wire). The steel wire of 0.56 mm diameter had a 0.29% offset tensile yield strength of 1689 MPa. Tests were conducted at low temperatures in the range of 23 to 140°C, and at initial stress levels of up to 75% of the 0.20% offset yield strength of the wire. The test duration was to 4000 h at 23°C and to 100 h at temperatures to 140°C. The test results indicate a faster rate of stress relaxation during the early stage of stress relaxation, and subsequently a slower rate of stress relaxation rate with increasing time, as is usually observed. An empirical equation has been determined that fits the experimental data very well under the given test conditions."

As I understand this it says they used two separate tests one at 73F and another at 284F.

I wish I could view the PDF without paying $25 bucks! That ridiculous!

Thanks,

Daniel

There is a certain model of Yamaha P-22 Studio Upright where the two highest single Bass strings often broke. I have replaced dozens of them. Whether it is stretch or any other phenomenon (probably a combination of both), a full half step of instability has always been the case for those.

Recently, I had two of them break on a school piano that I was tuning for a performance by a traveling group of singers known as Opera for the Young. I tuned the piano on a Monday for a performance on Friday. I had long given up hope of splicing those strings but in that case, I tried once again and the splice on the first one failed, so I made the decision to place an urgent order for the two strings.

I put them on on Wednesday afternoon and tuned them both at +30 cents. Within the short time that it took after chipping them to +30 cents and putting the action back in along with the pedal rods, the strings had dropped that 30 cents. So, I tuned them again at +20 cents. I returned Friday morning and they were both at -20 cents. I re-tuned them to +10 cents at that time.

I put a note on the invoice that they may need to be tuned again soon. I did not hear a complaint from either the performance nor did I get a call to re-tune them after that but I fully expect them to be markedly flat again the next time I tune the piano. I should mention that I installed them the way I usually do with an extra "hook" at the opposite end of the beckett in order to prevent any beckett slippage.

A few years ago, I replaced all of the wound strings on my home piano, tuning them at +20 cents several times. Within a day or two the first few days, they were flat of pitch. It took about 18 months before they stopped going flat. During subsequent pitch raises of the Bass, I could hear a peculiar "creeping" sound that was disquieting because I was not sure what was happening. However, that eventually stopped. I believe it must have been the tail pieces of the strings creeping and the tail loops elongating until they eventually settled to where there was no more movement.

Whether it is stretch or any other kind of movement that takes place when new strings are replaced, it matters little to the tuner or the owner/user of the piano what the reason is. Flat is flat and having to re-tune new strings many times over a very long period until they finally stop going flat is always a concern. It is not advisable to try stretching techniques or to tune wound strings more than +20-30 cents initially because any more than that may damage them. Plain wire and bridges can also be damaged by stretching techniques. You just have to grin and bear it.

I have decided not to stray from equal tempermant. I want the painist to be able to play in ANY key. (whether f# or the key of C). The chords should sound alike