Frank/Dave Perhaps we'll ahve to discard the involute theory as a simple model to help us think about this but Even so I visually see way less rubbing frictions with the angled capstan than many other conventional capstan set ups. I also would think that a wider faced capstan such as the old Stwy type would resist indentation some & provide a larger bearing surface to support the action weight/force in general. Thats my story...sticking to it. lol Dale -----Original Message----- From: pianoguru at cox.net To: pianotech at ptg.org Sent: Tue, 24 Mar 2009 6:50 am Subject: Re: [pianotech] Point of contact between capstan and wippen heel ---- david at piano.plus.com wrote: it doesn’t take long for the cloth surface of the wippen underside to wear to a different shape, such that in time convex capstan bears on convex wippen. Exactly. And that is another reason why the comparison to involute gears is eak. The involute curve, as applied to gears does not reduce friction. In act, it increases friction. To counter this in involute gear design, they use arder materials and improve provision for lubrication. You can't get much ofter than felt, which makes our application a weak candidate for the involute oncept. Frank Emerson -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090324/b0eb4f41/attachment.html>
This PTG archive page provided courtesy of Moy Piano Service, LLC