<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Action Ratio and Dip and Blow and Etc.</title></head><body> <div>Hi Terry and all,</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">Yes, there is room in the rep lever window to move rearward up to even three millimeters. Take a look at the following photo:</font></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><img src="cid:a0624081bc2b083c458d5@[192.168.0.6].1.0"></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">You can see that the jack long axis and the knuckle core axis are pretty close to parallel with one another.</font></blockquote> <div><br></div> <div>Yes, it looks quite good. That jack tail angle also looks better than most contemporary efforts (which dig holes in the lett-off button felt). But you probably could take the knuckle slot out to 17 mm without upsetting the alignment, since the jack is kicked back a little towards the hammer centre when at rest.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">As you can see, I increased the wippen heel height quite a bit to get the heel/capstan interface on the magic line at half blow - that modification has decreased friction a fair bit.</font></blockquote> <div><br></div> <div>Indeed, this is always a good move. But just look at the above image, and watch what will be happening as you move the knuckle further out on the hammer shank towards the hammer without changing any other parameters. Especially note what will be happening to the contact point between the knuckle and the jack contact face. It will be moving towards the wippen/hammer-shank line of centers. The same tendency will occur if you reduce the diameter of the knuckle. Also, as you move the knuckle out, the wippen/knuckle-contact-distance from the wippen centre will be reducing in length, while the distance from the knuckle to the hammer centre will be increasing. Therefore, the overall hammer/key ratio will be reducing just as it does when you move the capstan towards the balance pin. Both adjustments therefore will reduce the hammer/key ratio.</div> <div><br></div> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">Take a look at the lead in the keys in the photo below:</font></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><img src="cid:a0624081bc2b083c458d5@[192.168.0.6].1.1"></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">That's where my concern about lead stems from. All front weights are 0.96666 of Stanwood's maximum front weights.</font></blockquote> <div><br></div> <div>Yes, I suspect that this action has a hammer ratio which is too high. The number of leads is always a tell-tale sign of a higher than desirable ratio (assuming of course that the keyboard weigh-off was done just after checking the friction of all the key bushes and centers)</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">Are you thinking that the slight loss of efficiency at not having the jack perpendicular to the shank at rest will be more than offset by the action ratio becoming more efficient by moving the knuckle out?</font></blockquote> <div><br></div> <div>The relationship of the contact between the knuckle/jack contact with respect to the line of centres will be the most significant factor.</div> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">I've never moved a knuckle before.</font></blockquote> <div><font face="Arial" size="-1"><br></font></div> <div>While it doesn't take too long to plug the knuckle slot and re-cut it, I prefer to check an action at tear down these days and make a decision on what to order, so that I don't have to do major custom work at the time of re-assembly. You can get the overall ratio you are looking for by moving the capstan line alone, but if you've got an action with a 15.5 mm slot distance from the hammer center, and you're using contemporary weight hammers with say 10.5 gr for the lowest bass, you'll need to move the capstan much further towards the balance pin to achieve a desirable ratio than you would if you ordered shanks with a 17 mm slot distance.</div> <div><br></div> <div>Ron O.</div> <x-sigsep><pre>-- </pre></x-sigsep> <div><font face="Times New Roman" size="+1" color="#0000FF"><b>OVERS PIANOS - SYDNEY</b></font></div> <div><font color="#000000"><i>   </i></font><font color="#0000FF"><i>Grand Piano Manufacturers</i></font><font color="#000000"><br> _______________________</font></div> <div><font size="-2" color="#000000"><br> </font><font color="#000000">Web http://overspianos.com.au</font></div> <div><font color="#000000">mailto:ron@overspianos.com.au<br> _______________________</font></div> </body> </html>