Norman,
Through my visits and piano servicing in a number of different music schools I want to add a different dimension to this discussion, because there are more variables than just the piano and the hours used.
The style of playing has a large impact. Certain high level teachers have a way of pushing their students to really 'drive' the tone out of the piano. I have seen examples where a school was breaking a lot of treble strings, and the school tech noticed it seemed to be one professor's studio and the practice rooms frequented by that professor's students!
I have also seen it where a school rarely broke strings, but then they hired a new head professor and WOW - the strings started popping! So for this reason I think that different schools' experience will be very different.
In visiting Juilliard over the past few years, I have heard from the techs there that the practice room pianos (all Steinways) tend to start breaking a few strings after maybe 3 years. When the string breakage gets to where a string is popping each week, then they schedule that piano for new treble strings. They told me that, for them, this is every 5 to 7 years in the heavily used piano major practice rooms. They also often replace the hammers at the same time.
Hammer shape and action regulation has a great effect as well. As the hammer contact area become flattened with string grooves the stress on the wire goes up. If the letoff is also very close to the strings, this is the worst case. So if a school has the luxury of enough technician hours to allow it (this is a big 'IF' today!) a light hammer filing and touch-up regulation annually makes a huge difference.
And, the piano itself does have an effect. If the string angle is steep up from the capo bar (more than 19° angle in relation to the speaking length) the stress on the wire is increased. Related to this is if there is a large contact area at the capo (the sharpness of the V underneath). If the capo also is not hardened, together with a broad radius and steep duplex angle, the string breakage will be very serious after a few years. The string digs into the soft capo bar and settles into a long groove, so the string cannot pivot at the capo bar during hard playing. So the string fatigues much faster.
In this case the fix is to file the 'V' to a smaller radius (radius of 2.0 - 2.5mm is good), eliminating the string grooves, file the duplex counter-bearing bars to set the angle at 18° or so, file the hammers, polish the capo nicely, and install new strings.
Some people like the Paulello XM wire in high stress pianos as well. I have tried this on a few pianos just recently, so for me the jury is still out whether they do last longer. I do not care for the tone quality so much, though. This is very subjective, so your opinion will vary. :-)
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Don Mannino RPT
Kawai America Corporation
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Original Message:
Sent: 06-30-2019 09:21
From: Norman Cantrell
Subject: String Metal Fatigue Timeline
All
I service at an All Steinway school and we purchased a large number of pianos in 2003. Most were put into service in 2006 when the building was complete. I have 8 Steinway L's in the practice rooms for the piano majors. To date I am not experiencing treble string breakage from heavy usage. As we are looking long term at maintenance schedules what has been your experience on the age of a heavy use practice room grand that starts to need restringing due to metal fatigue?
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Norman Cantrell
Piano Clinic
Lawton OK
580-355-5003
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