<html> <head> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <meta name=Generator content="Microsoft Word 10 (filtered)"> <style>  </style> </head> <body lang=EN-US link=blue vlink=blue> <div class=Section1> I’d have to agree with Keith in all this.  While aligning the jack 90 degrees to the shank is not unimportant, there is some tolerance and it’s seen frequently when converting original dimension Steinway’s to 17 mm knuckles.  The friction at the jack is not even seen in the measured touchweight since the knuckle rests on the balancier.  The only friction change might be during the let-off stroke and even then, at let-off, the angle of the jack relative to the knuckle would have rotated through 90 degrees to the shank anyway.  If someone is seeing a change in measured friction by aligning the jack differently, they should look elsewhere for the answer.  Having the capstan/wippen heal interface properly located on the magic line is a different thing altogether since the degree to which it is misplaced will contribute to less efficient lifting and more sliding and thus in increase in friction.  When moving capstans or shimming out wippen rails (or choosing straight versus slanted heal wippens) attention should be paid to where the capstan/heal interface will fall with the new parts and they should be selected accordingly, not based on what was there to begin with.    Unfortunately, rebuilding actions without making new keysets is often a series of compromises.  In terms of priority, jack/knuckle angle is lower down on the list that other things I can think of.  As I said, it’s not unimportant, but neither is it the most important.       <div> David Love davidlovepianos@comcast.net www.davidlovepianos.com </div> -----Original Message----- From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of Keith Roberts Sent: Tuesday, October 30, 2007 6:36 PM To: College and University Technicians Subject: Re: [CAUT] Digest, Vol 1103, Issue 85 Moving Wippen Rail     <div> On 10/30/07, Richard Brekne <<a href="mailto:ricb@pianostemmer.no">ricb@pianostemmer.no</a>> wrote: In anycase, moving the whippen rail is a matter of creating this alignment and not a matter of changing touch weight. <div>   </div> <div> Sorry Rick but that doesn't agree with the data. The action I was just working on Dale weighed off yesterday and he had been trying to squeak an extra lead out of the keys. It was weighing off with 4 leads in the bass when regulated. After the rail move it weighed off with 3 leads. This is because the resistance arm when measured to the top of the jack is not a direct ratio to the effort arm. The force has to be translated through the jack first. Remember weigh-off is only to let off so miss alignment of the core to the knuckle core will make no difference as long as the jack is pointed at the center of the knuckle. </div> <div>   </div> <div> So to figure the force directed out the jack, you make the line from wippen center pin to the jack center pin the x axis and then the tangent line is the y axis. By the number of degrees you calculate the amount directed back down the x axis and then you figure the resultant force vector directed down the jack. Then resolve the force at the end of the jack to the tangent line of the arc from the top of the jack to the wippen center pin. There will be a slight movement of the magic line but when 2 mm is translated in degrees back to knuckle it is nothing. </div> <div>   </div> <div> In any event like David Love said and what my mentor thinks agrees with the data: there is a change in the amount of weight needed to balance an action and there is no measureable change in friction. Personally I don't see how you can change the effort arm of the wippen and not effect a change in leverage. </div> <div>   </div> <div> That's my story and I'm sticking to it. </div> <div>   </div> <div> Keith Roberts </div> </div> </div> </body> </html>