I think I would argue that the point of finest control is not escapement but the initiation of the key stroke. The friction in escapement itself must be so much greater than any capstan friction that I can't imagine how this might make a difference. While friction's effect might increase with speed, speed and momentum also mitigate the effects of friction. This is made quite obvious when weighing off an action and having to tap the regulation table to initiate breakaway. As you mention, however, the difference in measureable friction is probably so small that it's really of no consequence. The most efficient system, to me, would be lowest friction and the lowest ratio at the outset of the stroke. Thus the initiation of the stroke would be the smoothest and as the leverage and friction increased speed and momentum would compensate. The increasing ratio at the end of the stroke would, I suppose, facilitate power (though I think whatever power you've delivered to the system is probably not influenced that late in the key stroke) but more would facilitate soft playing by ensuring that the rate of acceleration was still increasing. It's all a bit theoretical though and while you might be able to calculate differences I wonder if you can really tell in practice. David Love www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of A440A at aol.com Sent: Monday, March 16, 2009 6:46 AM To: pianotech at ptg.org Subject: Re: [pianotech] capstain/wippen angle, was: key position at rest David writes: << Why wouldn't you want the minimum friction to occur the slowest rising rate of the key, the beginning of the stroke? The momemtum of the key will compensate for increasing friction later in the stroke. >> Two reasons: I think it best to have the least amount of friction and maximum ratio at the point of finest control, (escapement). The zero friction at this point assists control at ppp and the higher ratio provides maximum power at FFF. Reaching the the magic line at let-off provides this. The difference between maximum friction occuring at the beginning of the stroke or half way to the magic line is not measurable, but the difference in ratio is. So, why create a fall-off in the acceleration to avoid an immeasurable change of friction? I think friction's effect increases with speed, thus, placing it at the lowest speed in the event will minimize its effect. At this point, the major resistance is the inertia of the action parts. If the magic line is reached at let-off, what we have is friction decreasing and the ratio increasing throughout the stroke. Splitting the path on either side of the magic line creates a situation where friction begins to increase and the ratio decrease as we reach let-off. This can't be good. The same concept of steadily increasing ratio can be seen in the original idea behind Steinway's accelerated action; with the half-round slightly off-set proximally, the key ratio increased as the key was depressed, due to the fulcrum effectively moving towards the performer. In later production, the half-rounds appear to be drilled in the middle, thus negating the effect. Regards, Ed Foote RPT http://www.uk-piano.org/edfoote/index.html www.uk-piano.org/edfoote/well_tempered_piano.html <BR><BR><BR>**************<BR>A Good Credit Score is 700 or Above. See yours in just 2 easy steps! (http://pr.atwola.com/promoclk/100126575x1220439616x1201372437/aol?redir=htt p:%2F%2Fwww.freecreditreport.com%2Fpm%2Fdefault.aspx%3Fsc% 3D668072%26hmpgID%3D62%26bcd%3DfebemailfooterNO62)</HTML>
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