Here is an article written for the Partial Post, newsletter of the North Shore Chapter. Much of this is stolen from you guys, straight out. Mike Spaulding sent me a lot of material including Phil Glenn's material from 2003. I would like any responses or additions before sending this to print. Thank you all. The Weird Stuff: Young Chang Growing Action Brackets Bruce Dornfeld, RPT Many grand pianos made by Young Chang from 1990 to 1994 have unstable action brackets. The brands include Young Chang, Wurlitzer, Weber, PianoDisc and Cline. While the warranty has expired, Young Chang has been very good about getting new replacement brackets to us. Phil Glenn, RPT, while he was Young Chang’s National Service Manager explained, “The brackets are grey and die-cast from aluminum alloy. The vendor mixed the alloys incorrectly so that the metal becomes unstable. To our customers, I compare it to putting too much yeast in a bread dough mix. It generally takes from 2 to 5 years to start showing up. Do not judge the bad parts from appearance, because they may not show any signs of a problem. Remove them and throw them away… far away.” The problem that the player and you will notice first is the hammers block against the strings. After checking for other causes, like foreign material stuck under the keybed, etc., you should measure the action spread. If the metal is expanding the action spread will increase. The distance between the middle of the hammer center pin and the whippen center pin is the action spread. My preferred tool is a compass with a wheel for fine adjustment (photo 1). The center of the center pin is tricky to hold fast to with a tool like this, so locating the back of the hole for each center pin works better for me. For pre 1993 actions, the spread should be 112.5 mm. From 1993 and after, they should be 113.5 mm. The two actions also can be identified by the angle of their let off buttons; the newer ones are 90 degrees from the hammer rail, and the older ones angle back in toward the whippens. If the action spread is larger than the specs, the brackets are bad. The last job I measured by each of the four brackets before replacement. Where the factory spec is 112.5 mm, it was 113.0, 115.0, 114.0, and 112.5, from end to end. Things changed in the middle much more than the ends. If you take the action to your shop to repair it, take string height measurements for bench regulation first. Most of the actions I have found that need this had some regulation done at least once. If this has been done, you will need to do significant adjustments to let off at least. If no one has done any remedial regulation, the job could be done in the home in a half day or less. Getting a live person, or even a voice mailbox that isn't full, for Young Chang parts has been a challenge. It is best to dial direct: Sam Sun at 866-798-6979 extension 136. Have the model and serial number ready to get the right size brackets. Because the new brackets have thicker feet (photo 2), you will need longer screws (#8 – 1 ¼” round head) to secure the stack to the keyframe. On the workbench: remove the stack and place on bench with the keyframe out of the way. Record the action spread at both ends and by the inner brackets where possible. Remove an end bracket and replace it with a new one. Do not tighten screws now; leave them all a bit loose. Proceed to each bracket in turn so they are all on, but a little loose. Place the stack back on the keyframe and secure it with the longer screws, starting with the end brackets. The middle brackets should be secured with the rear screws before the front screws, since the 90 degree angle screws should be tightened first. You may need to plug and relocate some holes for the middle brackets. If the middle brackets are too long to fasten to the same wood on the keyframe, either reorder the correct brackets or glue and screw new hardwood to the keyframe to support the feet. When the stack is secured to the keyframe, it is time to tighten the hammer rail screws to the brackets. After the hammer rail is tight, the action spread will be set as we tighten the whippen rail. You may use the compass to measure the spread, but Will Truit, RPT has a more accurate method. He took a thin piece of 1/8” brass stock and carefully drilled two holes exactly 112.5 mm apart with a drill press. Then he put .050 center pins in the holes. After removing the center pins from the end hammer shank and whippen, and replacing the flanges on the rail, the guide is ready to adjust the spread. The center pins on the brass stock will both fit when the spread is perfectly set. Make sure all of the rail screws into the action brackets are tight. Remove the action stack screws and look at how the bracket feet all sit on the keyframe; shim any spots where gaps are. We don't want any twisting from unevenness here. After the stack is back on and all screws are tight, it is time to regulate. Let off, drop, and blow distance are the adjustments that would be off if they were adjusted to compensate for the growing action brackets. Jack alignment should be checked as well. When the action is back in the piano, be sure to bed the keyframe and adjust the strike point before looking at any other regulation adjustments. If your client wants a complete action regulation, that’s great – it’s due, but the adjustments above are the ones changed by the action bracket problem. I owe many thanks to Mike Spaulding and everyone who has posted to pianotech about this subject. Bruce Dornfeld, RPT bdornfeld at earthlink.net North Shore Chapter -------------- next part -------------- An HTML attachment was scrubbed... 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