Hello, It is not buckskin but ecsaine on Yamahas a kind of micro fiber product. I doubt it may react to water like leather. That said I also wish to be sure that the hump noticed is not due to some play or bad position of the jack dat the beginning of the stroke. If the cushion compress too much, the there is very high friction occurring between the jack top and the "buckskin" , can this friction push the buckskin or rob the tension from it, causing that deformation ? Good lubrification with Teflon powder should certainly help, but not very easy to attain there. Possibly there are more side effect to leave with too much play some actions than we believe. But also, taking back the play with the key capstan, while half the cause is lowered balance point induce a bad geometry also, this can be causing premature wear as well I'd say. So shimming under the balance is done , even with thin paper , before going farther in regulation - at the same time the dip can be corrected fast /rough shimming under the front rail. Checking the jack's alignment at rest may not be easy, but if we know what we are after it is certainly possible. I don't have a such large amount of vertical Yamaha under heavy use to treat so I only can hope for you that these are not hidden problems to come. I'll ask my friends of the conservatory about it. Best regards. Isaac OLEG -----Message d'origine----- De : caut-bounces@ptg.org [mailto:caut-bounces@ptg.org]De la part de Jim Busby Envoye : lundi 19 avril 2004 22:41 A : College and University Technicians Objet : RE: Re. Bobbling hammers on Yamaha upright So Jim, others, What's the real fix? File the buckskin, iron it, reglue it, water shink it (with distilled water)? I've had that "hump" and never found a quick way other than what Vinny said, or by tweaking the regulation. If only a few are bad ones, were they defective from the beginning, or did too much lost motion cause the jack to pound the hump there? With 337 uprights (203 of them Yamahas) you can see how this might interest me. Thanks. Jim Busby BYU -----Original Message----- From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of James Ellis Sent: Monday, April 19, 2004 1:53 PM To: caut@ptg.org Subject: Re. Bobbling hammers on Yamaha upright Yes Vince, changing to a thicker butt felt, and then re-regulating, might stop the bobbling, but it's not the fix I would like to see. That would also change the leverage ratio a little bit. The ratio is just fine the way it is. The problem is too much of a hump at the very front of the butt leather, making the jack have to move too far out before it will clear. This is the only Yamaha upright that I tune regularly that does this. It's about two years old, in a church chapel, and does not get used a lot, so it's not a matter of wear. As I said, the funny thing is, a few hammers do it badly unless I pound hard and really knock the jacks way back at let-off. The others don't, no matter how I play. Everything is lined up right on the money. At full key-stroke and let-off, neighboring jacks line up perfectly - same distance out. One bumps the butt leather, but the other does not. The other funny thing is, no one has complained about it. I don't think they even notice it. Next time I tune it, I expect to find a few more bobbling, at which time I will fix it. I'm glad I read all your various posts on the subject before it came time to tune this piano again. This is the first time it has started doing this. Having read your posts, I looked closely to see what was going on, and that's what I found. Thanks, Guys, Jim Ellis _______________________________________________ caut list info: https://www.moypiano.com/resources/#archives _______________________________________________ caut list info: https://www.moypiano.com/resources/#archives
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