Hi; Denise: Yes, this keytop replacement mistake is quite common. There is a check of proper alignment of the capstan and the key stick called the "magic line". Are you familiar with this test? Basically, you take a piece of thread and stretch it from the bottom of the key at the balance rail point, to the center pin of the whippen. If you press the key down halfway, the capstan contact point with the whippen heel should be on the "line" created by the stretched thread. The thread is used to create the "line", if you follow me. It is not apparent at a casual glance what the problem is. Doing this will reveal a lot of hidden problems. Suppose you put some new back rail felt on the keyframe, and now the keys have to be raised by adding punchings at the balance rail to get back the proper height and key dip. Now, you have to lower the capstans a lot just to keep the hammer line where it was originally. Sounds easy, but it creates a lot of problems with the geometry. You might want to check the archives and search "magic line". There is a series of articles in the Journal about key and action geometry a year or so ago. I can't remember the name of the series (somebody jump in here and help identify this). I made this mistake with the backrail felt on my mom's piano with a very compact upright action. I ended up with the action being extremely sluggish and unplayable, though at the time I couldn't understand how I had screwed up. In regards to the key buttons being at different heights on the pin, some of that is going to be there anyways because you need more dip for the sharps to raise the capstans to an equal level with the naturals when the keys are depressed. The easiest way to get more dip is to raise the key slightly at the balance rail. I can't envision what's going on with your action, so I'm sorry I can't comment. Removing the felt in the whippen sounds like a desperate move. You're going to have to replace it at any rate. (Sorry!). It does sound like you've got to go back and redo the keytop job and get the keys properly situated. You will learn a lot from this exercise. If it was easy you might miss some important details that you'd never have to deal with otherwise. So don't become discouraged. If I were to give some advice at this point, I'd stop everything and concentrate on the keytop problem. Anything you do at this point beyond that is going to confuse you further when the action doesn't work right. Go and get some thread and see if you can do the exercise I outlined above. I'll bet the capstan/heel contact point is not on the "magic line". Even if somehow it is, your geometry will never be right. It is possible that the key has been lowered at the balance rail to extent that the keystick is actually hitting the balance rail when it's being depressed, indeed causing a new fulcrum point. No way that action is going to work right as it is now without correcting the geometry problem. Soooo, it's time to move some mountains and get to work on the "real" problem. Forget what's been done so far, and start over doing it right. Hopefully some other techs are going to jump in here and correct me or offer better advice. I hope you don't mind if I post my reply to the list. (Otherwise, how did you find this discussion?). We're not engineers, but once we get off track by modifying the action or replacing parts, it's hard to understand where things went wrong. It is also common that new parts are just so slightly different than the originals that the action becomes sluggish, even though individually each piece has acceptable friction. I hope this helps. Paul McCloud > [Original Message] > From: Denise Rachel <pp-ff at verizon.net> > To: <pmc033 at earthlink.net>; <pianotech at ptg.org> > Date: 12/04/2009 12:33:43 AM > Subject: Re: [pianotech] Regulation > > Hello Paul, > > I've just gotten on this list, and the timeliness of this post is > perfect. I am having a problem regulating a Mason & Hamlin. I have > done extensive and exacting rebuilding on this instrument, including > new soundboard, but now that I'm almost done with the project, I can't > get it to play. I have installed all new Renner parts, and they seem > fine. I'd like to describe what I think is happening, and I'd be > grateful for your thoughts. > > The replacement plastic is about twice as thick as the original ivory, > and no planing was done. I noticed instantly that the buttons are not > even with each other, the white keys being lower at the front of the > button. So this is what I see: the white key does not go all the way > down, no matter how many punching I remove. Is this because the > capstain is digging into the whippen felts? Instead of the round top > of the capstain sliding under the felt, the straight back side of the > capstain is jabbing into it? When I force the key down really hard, I > see the key rises at the center rail. Some sort of invisible fulcrum > is being created between the rails. > > I've done the jack/knuckle adjustments, and roughed in the letoff and > drop on the bench. Springs are very tight still. At this stage the > black keys are behaving as I would expect. I have come across many > pianos where the jack addresses the felt at the front of the window > before the key is fully depressed, and the sensation is the same -- > mushy bottomless stroke. Just to be sure that this is not the issue, > I removed all the felts from the windows. > > I would love to hear your ideas. The person who recovered the keys is > a friend who lives nearby. I want to be absolutely sure I have this > properly diagnosed before I approach her. > > Thanks for your thoughts .... it would be nice to go about my > daily tunings without this nagging at me . . . . > > Denise > > > > > On Dec 2, 2009, at 10:09 PM, pmc033 at earthlink.net wrote: > > > Hi, Matthew: > > I've been out all day and just returned, so here's the scoop. The > > real > > cure for this problem is to determine (easy to do) whether the keys > > were > > shaved down a little bit so that the key is the same thickness with > > the new > > keytops as they were with the ivories. If the key doesn't have any > > evidence of being shaved, the keytops were simply glued onto the > > surface > > where the ivories were, and now the key is thicker. And that is a > > problem > > that isn't going to be easy to take care of. It means that you will > > need > > to remove the keytops and plane the keys down. I would suggest > > sending > > them out to a professional key service like Michael Morvan (he posts > > here > > often). If you simply shim up the balance rail punchings to make the > > sharps higher, the action is going to give you more problems than > > you had > > before because the capstans aren't going to be oriented the same as > > before. > > My friend, you are going to have to bite this bullet and get this > > done. > > You'll have to explain to the owner what has happened, and now > > you're going > > to make it right. Once the keys are the proper thickness, your > > sharp keys > > will be the correct height in relation to the naturals and you'll be > > able > > to regulate things to make it work. > > In order to regulate an action properly, you have to start from > > scratch. > > First thing is you bed the keyframe so that it sits on the keybed > > flat, and > > every keyframe glide contacts the keybed simultaneously. Then, you > > fit the > > keys and determine the correct height (you already said you had it > > right). > > And so on. Even though the keys are at the correct height according > > to > > spec, they are Thicker, and therefore the bottom of the keys is > > closer to > > the punchings. You will have to shim up the keys after you put new > > tops on > > them so that they sit in the keyframe at the correct height at the > > top, and > > the key dip is correct. > > Sorry to give you bad news. If you want to do the keytop job > > yourself, > > you can make more money on the total job. Check the archives for > > methods > > for planing down the keys for plastic keytops. > > I hope this helps. Best of Luck > > Paul McCloud > > > > > >> [Original Message] > >> From: <toddpianoworks at att.net> > >> To: <pmc033 at earthlink.net> > >> Date: 12/02/2009 9:12:18 AM > >> Subject: Regulation > >> > >> Yes, Paul, my client did say that she had the ivories replaced at > >> some > > point. > >> > >> The puzzling thing for me, though, is that the natural heights are > > exactly 2.5", which, according to specs, is correct. > >> > >> But like I said, the sharp heights are 3/8". So, you are saying if I > > increase the sharp height 1/8", I need to adjust the dip 1/8" more? > >> > >> I will try that, and then regulate those sharp samples. > >> > >> Thanks for the help! > >> Matthew > >> Sent from my Verizon Wireless BlackBerry > >> > > > > >
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