Dale, I must concur. When I string the Steinway's I rebuild, I don't get all those false beats in the treble. Never thought about that until you just said it. (light bulb lit).
Al Guecia
----- Original Message -----
From: erwinspiano at aol.com
To: pianotech at ptg.org
Sent: Monday, April 14, 2008 2:12 AM
Subject: Re: stretching wire -- a preliminary test
Jd/Bill
I have an observation based solely on experience. I can't prove it to any ones satisfaction but my own but here goes.
I sincerely believe that the wire can be deformed along it's length by over stretching & it is permanent. I state the case of every new Steinway. The treble seduction from not 70 ish on up are extraordinarily false. Now I don't want to get into bridge pins & all that again but my theory is that the stringers are over pulling this section excessively and creating the falseness by deformation.
I have my own shop experience to go along with this.
You see, I once had an excellent stringer before the Lovely & talented Beatrix took over that job.
Terry strung all my piano for about 5 years & she was very good. The only problem was that the notes in the no.68-70 on up were extremely false. One day as we were brainstorming this together she said well I always do everything the same I pull the wire up a half step over pitch ...just like you said. Shell shocked I said...I never subscribed to such a thing. It was a tense moment.
After this we only string pulling the wire only up to pitch, & the first pitch raise is only up to pitch. The next pitch raise we pull only 10 cents above pitch & then we let it settle.
Since doing this are false beats have been cut down by 80% or better.
We also switched to gold wire from mapes & this also improved things further.
So my assertion is that wire deforms when it approaches it elastic limit. Perhaps I'm off base but thats' my story & I'm stickin to it. My ears are happier but maybe this is a different piece of the puzzle
So tell me does this have any relevance.............if not I'll go back to bed....It's late
Dale
At 21:00 -0500 10/4/08, William R. Monroe wrote:
>I think the point for me is that there are other factors to consider >re: pitch drops in pianos than long-term elastic deformation of >wire, and they shouldn't be dismissed without due diligence.
Certainly not, but they can be eliminated in tests.
The test I am about to describe is very basic and not satisfactory to me, but if there had been no pitch drop from this test I would have waited longer before devising a more decisive test.
A length of 17.5 (1 mm) Röslau polished wire was stretched between two 7mm wrestpins knocked very tightly into a solid mahogany tapered piano leg about 42cm apart so that the wire was only slightly above the surface of the wood. The coils were well knocked down and the wire pulled firmly sideways while it was tuned to G-392. This requires a tension of about 150 lbs, which is roughly half the "elasticity limit" of the wire --300 lbs (Röslau advertises 395 lbs. as the breaking strain of this size).
Over the space of an hour the string was pulled and plucked repeatedly and made to hold its pitch exactly under repeated plucking.
During the day of the set-up there was no significant change in the pitch of the note.
Humidity and temperature remained practically constant.
When plucked about 24 hours later a fall in the pitch of the note of 4 or 5 cents was noted.
48 hours later the note is 9 or 10 cents flat.
We shall see.
The main objection to this test is that the unlikely but not excluded possibility of movement in or of the wood is not excluded. The next tests will eliminate this weakness.
JD
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