<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 5.50.4134.100" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face=Georgia size=2>Mistake 1; Assuming action geometry = would solve an upright weight problem.</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>Mistake 2; Assuming leading would = solve an upright weight problem.</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>Mistake 3; Assuming a little stronger = jack spring wouldn't hurt.</FONT></DIV> <DIV><FONT face=Georgia size=2>Mistake 4; Assuming... </FONT></DIV> <DIV><FONT face=Georgia size=2>Mistake 5; Assuming....</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>This is theory, I'm assuming I'm right.</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>I thought action geometry could solve = a touchweight problem on an upright. First clue; I have heard it said = (must be an old wives tale), "you can hang a heavy hammer because the weight of the = hammer doesn't matter in an upright".  True.  A mistake would be to = not lighten the hammer as much as possible. A too heavy of a hammer will = crush the butt leather and pressure the flange bushing and not have a clean = rebound. However, the ability to accelerate a heavy hammer is there. The key here = is knowing that the wippen in an upright is a 2nd class lever on the = lift and a 3rd class lever on return. In a grand, the opposite is true. So an = upright being a more efficient lift mechanism, mass is less important. = <STRONG>The upright action geometry is designed for proper</STRONG> <STRONG>distance/movement of the wippen</STRONG> and touchweight becomes = a factor of the spring tensions, a variable, instead of gravity which = is not a variable. You might want to change the geometry if the blow distance = was set at 1 and 7/8" with a key dip of 3/8" and a jack that hits = the letoff  rail. Damper lift also needs to be considered. Then the wippen = travel might need to be lessened.</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>Back to touchweight. The jack spring = is a significant factor in the touchweight. I had a 57 gram DW and a 37gr UW. = Both the tall Pianotech spring and the Schaff spring were too tall. I could = have determined this by measuring the height of the jack flange. The one on = this Knabe is short in comparison to the replacement options. So I replaced = the jack spring with a spinet jack spring from Pianotech and the DW became 47 = grams and the UW was 20 grams. I would have thought this was wrong if Michael = Gamble hadn't posted the target weights from the S&S manual. <STRONG>Thank = you Michael</STRONG>. Obviously the jack spring affects the UW far more than = the DW. It functions somewhat as a wippen return spring. It will aid in = lifting more weight at the front of the key. The effort of the jack spring is = a 2nd class lever. The effort of the hammer weight is a 3rd class lever and so = the hammer spring will have more effect on the DW than the UW. = </FONT><FONT face=Georgia size=2><STRONG>The springs control the DW and = the UW.  </STRONG></FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>Upward pressure is needed at the = capstan. This would be to maintain capstan/wippen contact during both the up and down = movement of the wippen. This upward pressure is limited by the weight of the = wippen and the low UW and the need of the wippen to drop quickly without the weight = of the hammer. Leading needs to balance the key against the wippen regardless = of hammer weight. The wippen needs to fall on it's own weight to allow = the jack to reset and have lost motion. <STRONG>Leading therefore should be to = balance the keys as an individual component.</STRONG>  Any change in feel = will come from the change in hammer weight on acceleration or messing with spring weights.</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>Please comment, discuss, call me = stupid or ignorant but substantiate and show the way.</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV> <DIV><FONT face=Georgia size=2>Keith Roberts</FONT></DIV> <DIV><FONT face=Georgia size=2>kpiano</FONT></DIV> <DIV><FONT face=Georgia size=2></FONT> </DIV></BODY></HTML>