Stephane, As you felt personally insulted, I will apologize to you publicly, so here I do. I apologize to you Stephane, to have presumed that your instruments are too heavy in touch, but with a 50 g BW, I harly could find an instrument nice to play. I hear you proud of your touch and tone, and you send there figures that show that you don't even try to match original's parts weight, or to weight off the keys so to keep a more usual touch. I don't call that restoration, that is all. If you want the good hammers and shanks you should obtain copies of originals, not using the catalog parts. I sometime get hot because some don't seem to undertand the same concepts and ideas that are lenghtly explained on this list, while acting as experts in the field. We of course neet to be satisfied by our results, bu that is not the same thing to put new parts on an instrument and have it musical and playeable. Day in day out, I spend numerous hours that I can't be paid enough for it to have old pianos or even more recent ones corrected to the point the action became controllable, the tone pleasing, and the piano tunable by a normal standard. How will I explain to my presumably happy pianist that just baught this restored instrument, that the hammmers have to belightened, the key weighted, etc ? Tht is why I tend not to make gifts, that should be lost anyway , actually. Time is precious as we get old. Sorry for your sensibility. Regards. Isaac OLEG > -----Message d'origine----- > De : pianotech-bounces@ptg.org > [mailto:pianotech-bounces@ptg.org]De la > part de Stéphane Collin > Envoyé : samedi 2 novembre 2002 20:32 > À : Pianotech > Objet : Re: action ratios > > > Hi David. > > I plan to do a more in depth study of your metrology. > Maybe I sould not dare to jump into this discussion before > that. But isn't there a certain analogy between ratios > given by geometry, and ratios given by weight comparing ? > If difference exists, could you explain that ? > > Best regards, > > Stéphane Collin. > > > > ----- Original Message ----- > From: "David C. Stanwood" <Stanwood@tiac.net> > To: <pianotech@ptg.org> > Sent: Saturday, November 02, 2002 3:51 PM > Subject: Re: action ratios > > > | Dear Stéphane & Friends, > | > | I see some confusion in the discussion about what ratio > is. This is my > | view: When we talk about touchweight we refer to weight > ratios and in this > | regards we refer to strike weight ratio which is the > amount of weight, at > | the front of the key, that it takes to balance a gram of > weight at the > | hammer. When we talk about geometry we refer to distance > ratios which is > | the distance the hammer moves for a given unit of > distance at the front of > | the key. Stéphane shows an analysis with mixed types, > some touchweight > | and some geometry. One or the other please! > | > | The discussion that we have been having is about strike > weight ratios > | unless said otherwise. The calculation > | of strike weight ratio is found by determining the Top > Action Balance > | Weight which is front weight plus balance weight. It's > the total upward > | force at the front of the key from the hammer/shank & > wipppen. From this > | we subtract the Wippen Balance Weight which is the Wippen > Radius Weight > | times the Key Weight Ratio. The result is the Strike > Balance Weight or the > | upward force at the front of the key resulting from the > weight of just the > | hammer/shank. Divide this by the strikewt and we have > the strike weight > | ratio. > | > | I would like to offer a more direct way of determining > strike weight > | ratio... a "Short Cut". It also might help some to > understand conceptually > | what it is.... > | > | Short cut method for determining Strike Weight Ratio: > | > | 1. Make sure the key bushings are free and lubricated > with try Teflon powder > | (generally recommended whether or not your taking this measure) > | > | 2. Make a platform jig that may be mounted on the back of > the key for > | holding temporary weights: > | > | http://www.stanwoodpiano.com/ratioshortpic.jpg > | > | 3. Flip up the hammer and put key leads on the platform > at the back of the > | key: > | > | http://www.stanwoodpiano.com/ratioshort.jpg > | > | 4. Put key lead weights on the platform jig and arrange > them so the > | key/wippen are zero balanced. The key is zero balanced > when you throw the > | key down so it bounces back to center and when you throw > the key up it > | bounces down to center in a like motion. If the motions > are different then > | move the weights until the motion is the same in either > direction. You can > | also use a gram gauge and move the key up and down at the > front. When the > | scale readings are the same in either direction the key > is zero balanced. > | If the key has no keyleads in it then you can probably > use a small keylead > | at the front end of the key without using the platform. > | > | 5. Flip the hammer/shank down and leave the temporary > weights on the back > | of the key. The weight at the front of the key is solely > from the hammer > | and shank as the key and wippen have been zeroed out of > the equation. > | > | 6. Measure Up/Down and calculate the Strike Balance > Weight (D+U)/2. > | > | 7. Divide the Strike Balance Weight by the Strike Weight > to find the Strike > | Weight Ratio. > | > | Measure at least six samples to calculate an average > level of SBW. I > | recommend notes 16,17,40,41,64,65 to get a sampling > across the most played > | parts of the keyboard. > | > | Hope this helps... > | > | David C. Stanwood > | > | > | > | >> 5 mm dip gives an average 25.5 mm hammer rise (linear, not > | >> angular, but anyway I couldn't achieve a precision > | >> measuring so this matters). I assume this is a 5.1 > ratio action. > | >> > | >> Sorry for WW and FW, but this piano is in very last stage > | >> of rebuilding, and waiting for customers, so I'm not about > | >> to pull the stack out of it now. > | >> > | >> But I measured KR through length between balance point and > | >> front key, just above the front pin (243 mm) and length > | >> between balance point and whippen center for the rocker leg > | >> (no capstan on older Bechstein) (140 mm). This should give > | >> us a KR of 140/243 = 0.576 > | >> > | >> Here are the other measurements > | >> > | >> note DW UW SW > | >> C-3 60 40 8.4 > | >> C-2 60 39 8.4 > | >> C-1 63 47 8.9 > | >> C0 62 39 8.3 > | >> C1 57 36 7.3 > | >> C2 56 35 6.5 > | >> C3 56 32 5.8 > | >> > | >> What do you think ? > | >> > | >> Greetings, and much respect. > | >> > | >> Stéphane Collin. > | > | > | > | > | _______________________________________________ > | pianotech list info: https://www.moypiano.com/resources/#archives > | > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives >
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