Hi, Will:
I've done a few of these, though I don't claim to be an expert.
Sometimes the two brackets in the middle are not going to set on the frame, but may be a little above the feet on the keyframe. Check to see that after you install the stack that the hammer rail is still straight, after you tighten the screws, and not bowed down in the middle. Especially after you put the action back in the piano. If you rebed the keyframe from scratch, be prepared to do a full regulation. Often the glidebolts are down pretty far.
I'm not sure about the spread numbers. If the knuckles and jacks line up, you're probably in the right place.
If the stack is lower than it was with the old brackets, you'll have to lower the capstans. If you were to shim up the stack, you'll probably find that the capstans were probably in the right place. And that the bore distance was ok too. When I do this job, I try to change as little as possible, so to save time. I've never had to shim up the outer brackets that I remember, but I've done the inner ones a few times. Keep a long straight edge to check the hammer rail along the way.
It does seem that the downweight is a bit high. You might look to see if the capstans line up with the "magic line" at half blow/dip. A thread pulled taught from the lowest part of the balance rail hole to the center pin of the wippen should intersect the point where the wippen cushion meets the capstan at half blow. If your capstans are below or above this "line", there will be excess friction and leverage problems. As you stated that you had to lower the capstans a lot, you might want to analyze the system carefully to see if there is some reason to suspect a problem.
I hope I'm not muddying up the waters. I don't pretend to be an expert in grand regulation, but usually with these YC actions, all that is needed is to crank the letoff buttons back up (after the last guy turned them all down in a last ditch effort to regulate the #%$@ thing.)
Just a few thoughts...
Good luck.
Paul McCloud
San Diego
----- Original Message -----
From: Will Truitt
To: pianotech at ptg.org
Sent: 01/27/2009 4:20:19 PM
Subject: [pianotech] Young Chang Growing Brackets
To the List:
I am hoping to get a little bit of advice from my action ratio genius friends on the forum. I have a Young Chang G-150 which I have gotten and installed new action brackets to replace the old growing problem brackets. As best I can tell, this piano was built in early 1992, which would put it on the cusp between two action spread values of 112.5 and 113.5 mm. The spec sheet from Young Chang which I got some years ago says, “Action spread should be set to 112.5 mm. Models newer than 1992 = 113.5 mm.” I took that to mean that pianos made after 12/31/92. Which probably means that this piano should be set at 112.5 mm. But it is a little ambiguous, and I have been trying to call Derrick Cornejo at Young Chang for the past few days for clarification, but he is MIA, his mailbox is full, EVERYBODY’s mailbox is full, and even the operator is missing!
I set the spread at 112.5 yesterday. This I did by taking a thin piece of 1/8” brass stock, and carefully drilling two holes in it at exactly 112.5 on the drill press, and then installing two .050 center pins through these holes. Removing the shanks and whippens from their flanges at the ends, I screwed the flanges to the rail. Then I loosened the whippen rail screws, and moved that rail back and forth until the two center pins would go into their respective holes in the flanges. I then tightened the whippen rail screws, locking in the action spread at that position. So I am pretty confident that I have been very accurate at setting the spread at 112.5 mm.
I also needed to retap the screw holes in the rails, as the old screws would not go in very far. Once I did that, they turned nicely. I also had to plug and redrill the holes in the keyfram that screw the stack to the keyframe, as the two center brackets did not line up with the old holes. And longer screws for the taller bracket feet. No worries here.
I took the action back to the piano today. Installing it, the hammers were still blocking against the strings. However, when I set the hammer drop far enough away to be sure to get let off, I was able to back off the let off screws and achieve proper let off on several test notes. I set the drop then. I had already set the jack height and position in the window.
The anomalies here are thus: I was just barely achieving cycling through let off, with little or no aftertouch, without removing front rail punchings. The manual asks for 64.5 mm key height (which the piano was properly set at). I was getting about 9.4 to 9.6 mm key dip, and could achieve the 10.2mm by removing cardboard punchings. And it feels ok. I set the hammer blow distance at the factory spec of 47mm, but had to LOWER the capstans to achieve 4 or 5 mm to get it down to that value. At which the bottom of the shank is sitting about 3/16” above the hammer rest rail felt, which is adjustable and at its lowest setting at that point. The bottom of the let off rail is sitting about 1/8” above the back edge of the whippen. So everything is working, but there is not much room.
I also took touch weight readings on two notes: Note 27 was 55 g. DW, and 29 g. UW. Note 88 was 53 g. DW, and 36 UW. (These test notes had been regulated).
At first I was wondering if the plate was set too low. I didn’t have my string height guage with me, but I was able to get a string height at note 77 of about 198 mm.
But I think the hammer bore is sufficiently accurate to the string height. Note 1 was bored at 57 mm, note 27 at 51 mm, and note 88 at 49.5 mm. There is very little wear on the hammers. At let off, the test notes shanks are parallel to the string plane, not over or undercentering to any degree. And, with the hammer blow distance set at 47 mm and the jack position in the window adjusted to line up the back of the jack to the back of the knuckle core piece, they form a straight line. At let off, the bottoms of the hammer tails are even with the tops of the back checks. All of these things are good signs for action set up. Capstans are centered under their cushions.
At least on my test notes, it seems like the piano is going to regulate ok. It FEELS ok (for a Korean piano)
The only thing that is holding me back is the fact that I am having to lower the capstans to achieve the 47 mm blow distance, and remove punchings to get the 10.2 mm dip (which yields plenty of aftertouch). That part is odd, but I am assuming that the piano was set to the correct values for blow and dip at the factory way back when.
The essence of it is that if I decide that I need to change the spread after I have regulated the action, the values I have set will go out the window and need to be done over again. So I want to be right the first time.
So what will it be, boys and giris – is your antenna going up, or does everything seem hunky dory and I should keep the spread value of 112.5?
Thanks for your contribution.
Will Truitt
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