John, apparently I'm just as dense as Jason, because I don't think it was clear either. I would guess that profile means the arc described by the curved surface of the contacting parts, but that's just a guess. Is this correct? Or is it the part itself? Kerry Kean www.ohiopianotuner.com <http://www.ohiopianotuner.com/> _____ From: John Delacour [mailto:JD at Pianomaker.co.uk] Sent: Thursday, January 14, 2010 8:41 PM To: pianotech at ptg.org Subject: Re: [pianotech] Action Ratios At 16:51 -0800 10/1/10, Jason Kanter wrote: John, could you please add a definition of PROFILE? Jason, I though it was pretty clear from my definitions, which you quote in your message -- see the definition of KEY RISE, rendered bold below. "Contacting profiles" is a Pfeifferism that both I and Nick G. have used in this thread : At 13:11 -0700 12/1/10, Nick Gravagne wrote: In brief, this conjugate relationship is intended to minimize friction by creating a "rolling" rather than "sliding" friction at half-stroke and thus "minimize the slide path" of the contacting profiles (capstan, whip heel, etc.) Here are shown the arcs traversed by the capstan and the lever heel. Friction will increase as the arcs diverge. [...] On Sat, Jan 9, 2010 at 4:34 PM, John Delacour <JD at pianomaker.co.uk> wrote:<snip> DEFINITIONS: The BASE LINE is a horizontal line parallel with the key drawn through the balance point of the key. KEY DIP: An arbitrary figure of 8mm is taken as the (perpendicular) downward travel of the front of the (natural) key. (8mm of arc would make a really tiny difference) KEY RISE is defined as the perpendicular distance moved by the contacting profiles (lever heel and capstan top). The KEY FRONT LENGTH is the distance along the base line between the balance point and a perpendicular drawn from the key front. The KEY BACK LENGTH is the distance along the base line from the balance to a perpendicular drawn from the midpoint of the profile (the top of the capstan). The PROFILE HEIGHT is the perpendicular distance from the mid-point of the profile to the base line. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100114/e32832ed/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 9143 bytes Desc: not available URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100114/e32832ed/attachment-0001.jpeg>
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