REPETITION

[Roger Jolly]

Hi Rogerio,
                 All the suggestions on this thread have been excellent,
one thought comes to mind if all centres and key bushings are correct.
Jack height with respect to balancier is some thing to check. On every
concert quality regulation I become anally retentive with regards to height
and position.  A must for max power and repetition.
 As a check try the following. very gently depress the heel of the jack you
should just feel a VERY small amount of friction as the tip of the jack
kisses the knuckle, the hammer should just 'wink'
or drop a small amount.  Releasing the jack slowly and watch it just return
to the spoon. If this adjustment is difficult to do, its a fair bet that
the knuckle has started to flatten. A cheater fix is to take 1/4" strip of
sand paper and strip file the knuckle to get the rounded shape  back on the
knuckle. Rub some powdered Teflon into the leather and try again.
  If the knuckles have flattened that badly perhaps it's time for new
hammers and shanks. On our University pianos after the third hammer
reshape, repetition does drop for the combined reason of loss of hammer
mass, and worn knuckles.
 Developing a very sensitive feel in you index finger, so that you can feel
every nuance of the jack is the best tip I can give to fine grand regulation.
 Hope this helps, but please post the your findings, we are all curious.
Regards Roger



At 06:10 PM 02/12/98 +0930, you wrote:
>Adjust the repetition springs so that they lift the hammer (without jumping)
>after you release the key pressure slightly and the hammer comes out of
>check.   If the tension on this spring is too little the jack can't get
>under the roller fast enough to give proper repetition particularly on
>repeated soft notes.
>
>
>Tony Caught   caute@accessnt.com.au
>
>--Original Message-----
>From: Avery Todd <atodd@UH.EDU>
>To: pianotech@ptg.org <pianotech@ptg.org>
>Date: Wednesday, 2 December 1998 8:14
>Subject: Re: REPETITION
>
>
>Hi  Rogerio,
>
>   Sounds like you've pretty much covered most everything. How about the
>backckeck adjustment? You say the friction is very good but you mention
>it in relation to the knuckles. How about the pinning of the hammer shank
>flanges, wippen flanges and jacks? Is the repetition spring groove gummed
>up with graphite or anything else?
>   Just some thoughts. Below is a list of grand regulation measurements
>from an OLD handout I got at a convention many years ago (probably the
>1970's). You don't say how old the piano is but I assume the measurements
>would be about the same. I don't have anything newer.
>   Let us know when you find the problem. Hope this helps.
>
>Avery
>
>>     I am with a great problem with a YAMAHA grand model G2 and I need
>>help. All the measures that I did on it I think that they are very good:
>>hammer weight, letoff, drop off, the jacks are  correctly under the
>>knuckles, key deep etc., etc. but the repetition is poor  ! The friction
>>is very good ( I used powder micro  Teflon).The repetition springs are
>>good. There are a problem : I haven't the Yamaha  measurements and I used
>>the relation key deep-hammer travel 1:5. What can I do in order to
>>increase the  repetition that is poor. Rogerio Cunha - IC Member of  the
>>Guild.
>
>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>Key Height (keybed to underside of key covering) - 64 mm (+1  -0.3)
>Key Travel - 10 mm (+0.2  -0.3)
>Hammer blow - 48 mm (+0  -2)
>Let Off - 3 mm in bass graduating to 1.5 mm in treble
>Drop - Let off plus 2 mm
>Sharp height - 24 mm (+1.0  -1.0)
>Backcheck - 16 mm in bass graduating to 14 mm in treble
>
>Just in case someone else has messed it up, the action spread (wippen
>flange center pin to hammer shank center pin) measurement is 112.5 mm.
> 
Roger Jolly
Baldwin Yamaha Piano Centre
Saskatoon and Regina
Saskatchewan, Canada.
306-665-0213
Fax 652-0505