Sice I started the S & S rest cushions thread that became CAF thread, my final solution involved many many things. I started with using protek to free the hammer flanges (remember the piano was outdoor for a week before this concert), Then I did the rep. springs that were a little weak. I did the wink test and all was good. What I didn't like was the fact that when aligned with the back of the knuckle's core, the jack had a broken line with the core (the jack was going at a backward angle to the knuckle core). I was still having failure. I also noticed that the hammer tails just after letoff were a litttle high from the top of the backchecks. Not much I could do there the day of the concert. Also, the angle of the backchecks were allowing the hammers to go down too much on a hard blow or when I pushed them down with my fingers after checking. So I changed the angle of the backchecks (moved the bottom toward the wippen while keeping the top almost at the same position). This helped a lot but I still had a few notes with failure. These were taken care of by easing the front keybushings a little and lubricating the keypins. The piano ended up being playable with no failure, but the tech had a hard day. Marcel Carey, RPT Sherbrooke, QC > Date: Mon, 17 Aug 2009 12:53:53 -0500 > From: cramer at brandonu.ca > To: caut at ptg.org > Subject: Re: [CAUT] CAF > > I agree that the cushions are there for a purpose, and on one occasion where > they needed to be thinned, I actually had to shorten the regulating screws > as well (clicking), though these were still well below the shank-rest line. > > All the same, I'm curious if our colleague (sorry I've dumped my deletes) > with the action with the CAF problems tried winking the jack to see if the > height regulating-button is bobbling (spring too weak to hold the lever > down)? > > If it's bobbling, adding cushion thickness might mask the problem, but it > sure as heck won't fix it. > > I'd also be real curious as to how many of our suspected CAF causes could > actually pass the (2) jack tests and still fail to repeat? > > Mark Cramer, > Brandon University > > > -----Original Message----- > From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of > Richard Brekne > Sent: August 17, 2009 12:39 PM > To: caut at ptg.org > Subject: Re: [CAUT] CAF > > Hi Fred. > > Yes I understand this... and of course have run into it, and I agree > that the degree the rest cushions act as a rebound for the shank is tied > to the hardness of the blow. I just never really thought about how often > the cushion actually serves this purpose. And I've not really considered > it in a repetition speed context. Most often when I see the shanks > <<too high>> above the cushions its because they truly are too high and > the hammer line simply needs to be dropped along with re-regulation of > closely related parameters. This is one of the reasons I do not hold a > 10 mm key dip as a spec written in stone as my good and respected > friend André does. I'd rather stick close to home on hammer blow > distance and fudge more on key dip...and perhaps a tad on letoff to get > an acceptable aftertouch. > > Eric and I had a nice conversation at the Bergen Festival this year > about a closely related subject.... finishing off the regulation he > likes to fine touch letoff/drop by adjusting the jack rest position to > get both actuated simultaneously. I mentioned I liked to also float the > rep lever height relative to the jack. Both are to a very small yet > effective degree fudgeable. > > Cheers > RicB > > Fred writes: > > ...There's the sympathetic buzz, but there is also a click on > impact, if a nut is "just loose." And it happens typically from mf > up in dynamics. Hence, the shank must be hitting the rail. I can't > say I have done detailed research (checking exact regulation > parameters and whatnot), but I have observed this very, very often, > and with the shanks set at normal distance from the felt on the > rail. So it is hitting the felt and compressing it enough to set > the wood in motion. BTW, I find that most individual cushions on > wipps have at least moderate indentations in the middle after years > of play (especially in the middle where they are played more). It > isn't because the shanks were resting on them. > > > _________________________________________________________________ Avec Windows Live, vous gardez le contact avec tous vos amis au même endroit. http://go.microsoft.com/?linkid=9660830 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20090817/a701a039/attachment.htm>
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