This problem of screw angle driving the flanges to an uneven resting place is well documented in Ed McMorrow's book. He does a good job of illustrating it and discussing the solution. Alan > From: Fred Sturm <fssturm at unm.edu> > Reply-To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org> > Date: Wed, 20 Aug 2008 12:56:18 -0600 > To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org> > Subject: Re: [CAUT] S&S hammer flange rail material > > On Aug 20, 2008, at 6:51 AM, Chris Solliday wrote: > >> The one deviation from factory that I do now is add a washer on the >> top of >> the flange. It helps keep the flange level and particularly keeps >> the front >> from moving up or down which can alter the centerpin height. I think >> that it >> is important to maintain that measurement for many obvious reasons. > > Talking about the front of the flange moving up and down, I had an > early 1980's B I put new parts on last year, and when I had installed > the shanks and flanges, the fronts were all over the place. Put a > straight edge on, and there were gaps up to maybe 1.5 mm between the > highest and lowest. I traced this to bad drilling: the screws were > angled coming out of the rail, and they carried the flange with them. > (Put a straight edge next to the screws, and the drilling line had > about as much variance as the flange level). > My solution was to enlarge the screw hole a bit fore or aft (angle > matching the screw's, done with a round file), shim front or back of > the flange (all the way across, on the curved part), and then I found > I needed to chisel the top of the flange where the screw bears on it > at an angle to account for the angle of the screw. Otherwise, the > screw top would overcome the action of the shim. Not all that much > work, once I figured it out, but it sure was disconcerting to find. (I > didn't get it perfect, just addressed the worst culprits and figured a > wee bit of variation - 0.5 mm or so - wouldn't hurt that much). > Having those flanges uneven like that makes regulation a little > strange, especially the drop screws. I had had problems with that > action all along (original parts), but the most obvious part of it was > the too short tails (closest possible checking at 7/8" or more), and > so I never really looked into it, figuring I'd replace parts pretty > soon. > Anyhow, it's something to watch for. I've seen it on other Steinways > to lesser degrees, but this one was amazingly bad. > I think the new pan head, low profile screws have enough surface area > to make a washer unnecessary, but some of the old screws have pretty > narrow heads, so adding a washer isn't a bad idea. > Regards, > Fred Sturm > University of New Mexico > fssturm at unm.edu > >
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