Using hard blows to test stability can be effective, but they can also cause damage to hearing, joints, and the piano.
Not only that, they are fatiguing and can annoy the customer.
The Bend Test is a nice alternative that can be done to test stability without having to resort to damaging hard blows.
Correction. 2:20 "That's really not what this lesson is about."
How to Learn How Much Bend is Too Much and How Much is Not Enough
It's not hard to imagine a stable string that goes out of tune if you bend too much, or an unstable string that tests as stable because you didn't bend enough during the test.
The following procedure is designed to help you get a feel for how much bend is appropriate for a given string. After a while you'll get a feel for how much bend you need to use on any string to accurately test its stability.
Method 1
1. Tune the string using whatever technique you think will produce a stable string.
2. Give it three hard blows. (If you aren't sure that you can hit it hard enough, try playing the note loud 10 times with the sustain pedal on all the time. This really challenges the stability.)
3. If it's stable, try the bend test on it. Increase the force slowly until the pitch changes. That amount of bend was too much. The right amount of bend that will correctly test the stability of that string is just a bit less than the bend that caused the pitch to change.
Method 2
1. Tune a string.
2. Do the bend test.
3. If it passes, play three hard blows or use the "10x with sustain" technique described above.
4. If the string stability fails under the hard blows, you didn't use enough bend in your bend test.
Remember: A long NSL or one with high friction and a lot of bearing points, will require more bend to change the tension by the same amount as less bend on a shorter NSL. (Hooke's Law)
Watch Lesson 9 and then...
