Action modification results.

[Barbara Richmond]

Jon,

Knuckles out to 18.5 mm?  Do you run into many actions that use this 
specification?

Thanks,

Barbara Richmond, RPT
still working it all out in my head...


----- Original Message ----- 
From: "Jon Page" <jonpage at comcast.net>
To: <pianotech at ptg.org>
Sent: Sunday, February 04, 2007 9:57 AM
Subject: Action modification results.


> In the past few months, I've had 2 Young Changs and 1 Samick come
> through the shop. Great improvements have been made on all in
> regards to action geometry but I didn't document until this last YC.
>
> a. original survey
> b. Reshape hammers/taper/re-arc tails
> c. move knuckles out 1mm on shank to 18.5mm
> d. move stack back 3mm
> e. alter FW to target 38 BW
>
> Survey of C4
>    UW  DW  BW  F   SW   FW  SBR
> a  32   60    46  14  10.9  32    6.4
> b  26   52    39  13    9.9  32    6.3
> c  24   44    34  10    9.9  32    5.8
> d  22   38    30   8     9.9  32    5.4
> e  30   46    38   8     9.9  24    5.4
>
> Description:
>
> a.  The piano was difficult to play, one reason the owner sold it,
>      he wanted a lighter action and decided to go for a digital.
>      BTW this also is a PianoDisc.
>
> b.  Hammers were in the high top range. Reshape, square the tail
>      to the shank, taper width 10.5mm at top 7.5mm at tail. Remove
>      staple (.2g) from notes 64 and up to reduce shoulders.
>      Ending at 3/4 medium range. (at #64, SW increase jump)
>
> c.  Knuckle core aligned forwards of jack center pin. Action spread 113.5,
>      no room to shorten spread because the jack was already forward of
>      center on the let off button and capstan was on the rear of the 
> cushion.
>      Height of wippen rail OK. Jacks were burying into the rep stop felt 
> even
>      with 9.5mm dip and 48mm blow.  I expected a greater difference.
>      [In retrospect, I might have eliminated this procedure but I didn't 
> like
>      the angle between the jack and shank at rest.  The knuckles were 
> relatively
>      loose in the slot so no damage was done in removal and I reused them.
>      A veneer shim was glued in alongside the core upon reinstallation. 
> Then the
>      final survey (e) might have appeared something like this: 
> 30,46,38,11,9.9,29,5.9]
>
> d.  The capstans were on the rear portion of the cushion felt and behind
>      the Magic Line. The bass and tenor hammers were at odd angles on the 
> rail
>      to fit the strings.  Relocated stack back 3mm to align capstan on 
> cushion center
>      and Magic Line. This also improved the strike point in the treble 
> although I had
>      to move the keyframe forwards .75mm (predetermined before stack 
> location).
>      The bass and tenor hammers spaced to the strings with the shanks at
>      more comfortable angles to the rail and wippens.
>
> e.  Plays like a dream with minimal after touch. The FW is still high but 
> without
>      assist spring wippens there's not much else to do. 10mm dip, 45mm 
> blow.
>      Fortunately the hammers allowed for needle voicing which brought it 
> right down.
>      I think that even the PianoDisc operates better.
>
> Due to reducing the action ratio, the letoff buttons had to be turned up 
> to nearly
> maximum. This probably will cause some difficulty in their adjustment once 
> the
> hammers become worn.  For the next job, I'll either remove the buttons and
> remove ~3 to 4mm from the bottom or install wippens which have a wider 
> angle
> between the fly and tender; perhaps one with a screw adjust spring similar 
> to the
> Tokiwa M&H wippen, if not that wip with appropriate flange (preferred 
> option).
> I need to pull out the parts kit for comparisons.
>
> The Samick came out best of all because I was able to apply a Stanwood 
> TouchDesign
> since it had the spring assist wippen already (no screw adjust :-( This 
> needed to have
> the stack moved back, knuckles moved out on the the shanks, wippen rail 
> raised
> 1.5mm and spread increased to 114mm, hammer weight reduction with 
> shaping/tapering/arcing.
>
>
> NEXT !
> -- 
>
> Regards,
>
> Jon Page
>