On Wed, Jan 6, 2010 at 2:15 PM, V T <pianovt at yahoo.com> wrote: > Hi William, > > I think the concise explanation is that most of the inertia on the down > stroke does not come from the key stick with its lead. The hammer weight > is the largest single contributor. So, you might as well chip away at > that first. Reducing the action ratio is actually more effective because > of the things Frank said. Rotational inertia is proportional to the > radius squared, but only to hammer mass to the first power. > > So, if you reduce hammer weight by 10%, you get an improvement that is 10% > of the original contribution from the hammer. However, if you reduce the > action ratio by 10%, you get 0.9*0.9=0.81 which is a 19% improvement over > what the hammer was contributing before. > > As a side benefit, once you reduce the hammer weight and/or action ratio, > you can trim off some lead from the key stick and get a smaller > improvement there too. > > Another very simplified way to look at it is like this: > > A 10 gram weight on a 30 inch end of a see-saw has much more effect on the > inertia than a 25 gram weight on the end of a 5 inch arm. > > Vladan > > Thanks Vladan. I agree that hammer weight needs to be addressed prior to leading. I think my main flaw may be in ever seeing that leading could be anything other than a symptom of the rest of the system. Address the systemic issues first, leading then is done to match the system, and, not isolated and adjusted simply for the sake of making an inertia change at the front of the key. -- William R. Monroe, RPT -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100106/bbc19b1f/attachment.htm>
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