[CAUT] CAF

[Marcel Carey]

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.
> 
> 
> 

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