Problems with semantics aside, there seem to be advocates for both sides of the issue. They can't both be right. Honestly, I don't know what the answer is. In terms of practicality (a separate matter) I would not hesitate to raise the string height fractionally for fear of a slight change in leverage (if there is one). Getting the bridge up to an acceptable height if it is vertically challenged would, in my view, trump any changes that might be introduced to the action. I find the opportunity to vary the bore distance in virtually every Steinway I rebuild even if I go to such pains to level the plate, raise the treble side, make the bridge height more uniform, manipulate the aliquot thicknesses, add vertical hitches, etc.. If the string heights are fractionally off, I usually don't do anything but with this B I'm currently working on I probably will account for the 3+mm rise in string height from the low tenor to the treble. It does pose a certain dilemma though: I could alter the bore distance and change the leverage, or I could use a uniform bore distance and, because the string heights vary, alter the regulation. Which is better, I wonderJ? David Love www.davidlovepianos.com From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Jude Reveley/Absolute Piano Sent: Tuesday, March 24, 2009 6:51 PM To: pianotech at ptg.org Subject: Re: [pianotech] Increasing bridge height I agree in spirit while I take issue with your premise. Perhaps I'm too hung up on symantics but to answer the question truthfully, does a change in string height that is matched in a change of hammer bore affect the leverage? The answer is undeniably yes. Granted a 5mm string ht/hammerbore change might only reflect a change of a few tenths per unit of action leverage. As to whether the change is significant or anymore of a factor than any other inconsistency within a piano from note to note is another matter. My point is to encourage accurate statements and to define the parameters in which we are working. To encourage changing string heights without a discussion of the affects on entrance height and action geometry is risky. It's tricky business, fer sure. Jude Reveley, RPT Absolute Piano Restoration, LLC Lowell, Massachusetts (978) 323-4545 ----- Original Message ----- From: "John Delacour" < <mailto:JD at Pianomaker.co.uk> JD at Pianomaker.co.uk> To: < <mailto:pianotech at ptg.org> pianotech at ptg.org> Sent: Tuesday, March 24, 2009 7:22 PM Subject: Re: [pianotech] Increasing bridge height > At 11:24 -0700 24/3/09, David Love wrote: > >>It does? How. If you raise the string plane and increase the bore >>distance accordingly so that the shank angle at rest is the same as >>it was before, how does the leverage change? > > It doesn't, of course. A tiny difference in the initial touch weight > will result, but so tiny as not to signify anything. > > JD > >>>Of course, changing the bore distance does affect the entire action >>>leverage... >>> >>>Jude Reveley, RPT > > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090324/41633ca6/attachment.html>
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