This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Vince- Wow! Easy to calculate. (I thought it was one of those progressions to = the infinitesimal formulas.) This gets exactly to the unanswered question when setting front weights, = i.e. one in front or two in the back? etc. In fact it should be fairly easy to make a reference chart in, say half = inch increments. I'm rebuilding an action after Xmas, and I just might knock out the old = weights, plug the holes and go for broke. Thanks very much! This is a real Xmas present! Ed Sutton ----- Original Message -----=20 From: madelyn mrykalo=20 To: College and University Technicians=20 Sent: Friday, December 19, 2003 8:47 AM Subject: Re: Touch weight Ed- We measured the weight in grams of a lead for the mass (m). I.e. 14.1 = grams for a 1/2 inch lead is usual, then for r we measured the distance = of the lead from the middle of the balance hole to the middle of the = lead in inches. So I=3D14.1X4" would be for one lead (I just picked a = figure 4" for the distance). Then if there is another lead, do the same = for it, adding it to the first lead. So I=3D14.1X4" + 14.1X2" (if the = second lead is 2" from balance) and so on. This gets some figure that = sort of arbitrarily represents the moment of inertia, larger in the = bass, and graduating to smaller as we go up into the treble. I think = with some research the moment of inertia figure can come to mean = something to us. Empirically finding out what kind of figures pianists = like would help set a general standard, I think. It seems to me right now if you can get those figures to graduate = smoothly you can really even out the feel. Another question arises as = to should we smooth out those figures between the sharps and naturals or = let the sharps have a "lighter" number as they naturally do, because of = their shorter length. Ed Sutton <ed440@mindspring.com> wrote: Vince- Never having learned calculus, I don't know how to work a formula = like this. Assuming that I have -Strikeweight continuity within Stanwood's suggested range -Frontweight continuity within Stanwood's ceiling -Even and acceptable DW & UW How can I use this formula to improve action performance? Thanks! Ed Sutton ----- Original Message -----=20 From: madelyn mrykalo=20 To: College and University Technicians=20 Sent: Friday, December 19, 2003 12:56 AM Subject: Re: Touch weight Hi- Of course you can have acceptable DW's & UW's and at the same time = have a wide range of moments of inertia, some which may be acceptable = and some which may not be. Or the front weights could be too high. = That's why I don't think UW/DW alone tells us enough about how the = action "feels". =20 =20 Here is a formula for moment of inertia (I): I=3D m1r12 + m2r22 + m3r32 + ... + mnrn2 =20 =20 Where m is the mass and r (radius) is the distance that the mass = is from the balance hole of the key. The key itself has some moment of = inertia too. =20 So the action in question (Wim's D) might weigh off acceptably (DW = and UW), but also may have a too heavy a front weight, and/or moment of = inertia. =20 Stanwood has come up with a good standard of front weights. = Moment of inertia standards are a little more ambiguous at this point. = More importantly is that the moments be reasonably smooth from key to = key. Vince Mrykalo University of Utah -------------------------------------------------------------------------= ----- Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/caut.php/attachments/52/fb/07/0a/attachment.htm ---------------------- multipart/alternative attachment--
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