One scenario is that the screws are creating a bulge of wood, yes, by bottoming. The rail is hard wood. The tip of the screw tries to penetrate beyond what was originally drilled, but the forces are such that what happens instead is that the screw pushes wood up the threads, so to speak. The compression resistance of the wood at the bottom of the hole is greater than the ability of the wood contacting the threads to press the tip through. Something has to give, and what gives is the wood in contact with the threads. So you get just a little bulge right around the screw, and the flange is tight there but looser everywhere else. Don Mannino's suggestion of two strips of sandpaper, one in front and one behind the screw, is a good one, and would address the possibility I describe. I think the stuff Yamaha uses is nice (a strip on an aluminum rail). Seems like about 80 grit, but a red amalgam rather than aluminum oxide or garnet, like the stuff on sandpaper discs for disc sanders and the like. With the papers that have individual grits glued to the backing, some of the grits (bits of sand) can come loose and walk around, and make for less stability. The amalgam stuff (if that is the right term for it) seems thicker and more stable. If you have thicker paper, you will also probably eliminate the tip of the screw bottoming, so you won't be continuing to deteriorate the integrity of the wood threads (this kind of scenario leads to stripped holes). Regards, Fred Sturm University of New Mexico fssturm at unm.edu On Jul 10, 2009, at 1:56 PM, denisikeler at aol.com wrote: > Thanks for all the fast replies! > > When I tighten the screws tight, they seem very tight. I'm mean, > you are not able to move the flanges that easily with your hands. > The hammer rail is wood, how can the screw bottom out? > > The hammer rail bulging makes sense. That had not occurred to me. > > First I'll try screwing the screw into the rail without the flange > to see if there is a bottoming out issue. Then I'll remove the > sandpaper and try the 2 strip approach. What grit would someone > suggest? > > Thanks again! > Denis > > > -----Original Message----- > From: Don Mannino <DMannino at kawaius.com> > To: caut at ptg.org > Sent: Fri, Jul 10, 2009 11:11 am > Subject: Re: [CAUT] Wandering Hammers > > Denis, > > Between Jon Page and Marcel Carey I believe you will find the best > answer. Either the screws are bottoming, or the hammer rail is not > flat on top. Another washer will fix the screw problem, and using > two narrow strips of paper on the rail instead of one big one will > correct for any bulging of the wood rail. > > Don Mannino > > From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf > Of denisikeler at aol.com > Sent: Friday, July 10, 2009 4:57 AM > To: caut at ptg.org > Subject: [CAUT] Wandering Hammers > > List, > > At the Flint School Of Performing Arts, I have a Baldwin SD that the > hammer spacing will not stay put. About 7 years ago I put hammers > shanks and flanges in it. I used Renner USA shanks and flanges. > The problem is, no matter how hard you tighten the flange screw, the > hammers eventually move left or right after a few hours of heavy > playing. > > Some of my Ideas are: > > 1. replace the sandpaper on the rest rail with a heavier grit, which > might necessitate a slight let off and drop adjustment. > 2. the flanges have that little "notch" in the back, so I thought > installing bridge pins through the notch right into the rest rail. > I used to have a 9' Bechstein that I took care of that had the > same. > 3. remove a small amount of wood under the flange, so that > tightening the screw would transfer some of the grip out to each end > of the flange. My least favorite option. > > Any of you ever had this problem? Any help is appreciated. > > Denis Ikeler > > An Excellent Credit Score is 750. See Yours in Just 2 Easy Steps! > > An Excellent Credit Score is 750. See Yours in Just 2 Easy Steps! -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20090710/b7a469cf/attachment.htm>
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