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 >
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