Mysterious unsolvable Yamaha double-striking uprights

Susan Kline skline@peak.org
Tue, 12 Jul 2005 00:03:54 -0700


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At 11:48 PM 7/11/2005 -0700, you wrote:
>I mentioned the plastic jacks because it was the only difference that I 
>could see. I don't see why they would make any difference either, though I 
>have not actually taken one out and held it side-by-side a wooden one.
>
>Loose hammer flanges sounds like a real likely culprit. How many times 
>have we checked the pinning on a brand-new hammer flange only to see eight 
>or ten swings? Since this is dealer prep I think I was actually avoiding 
>that as a possibility. However, now that it's been suggested as a possible 
>solution I can take that back to the dealer and find out how much they 
>want to invest.
>
>Springs will be the test after that. All I need to do is slip it out from 
>under the loop and stretch it out a bit, right?
>
>-- Geoff


Hi, Geoff

I suppose you could take an identical-sized wooden jack and install it in 
place of the plastic one, making sure that the pinning was the same, and 
see if the double-striking was any different.

I can see a good reason for initially loose hammer pinning in pianos 
destined to be sold in many different climates (like in North America.) If 
you pin so that the hammers are _just right_ in a dry climate, like the 
high desert, and then send the same piano to the South East, the hammers 
will seize. In this case, they probably decided to err on the side of 
safety, figuring that a loose hammer was better than a seized one.

I would try a few samples, pinning quite a bit tighter, and see how they 
work. If they seem good, assuming that the piano is not going to be exposed 
to muggy heat later, you could repin the whole set without all that much 
trouble, using Don Mannino's style of broaches.  I expect that you would 
find the flanges very uniform. A bit of hammer spacing afterwards, of course.

I haven't strengthened hammer springs on Schwander actions much, but I 
imagine one would proceed as you describe. Slip it out of the loop, using 
the Hart Spring Tool, pull it to a higher angle, (with the tool in the 
little kink at the end) then slip it back in.

Susan


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