<HTML>Joe, If you figure the jack is pushing on the knuckle, it would be causing th= e shank to bend backwards(downward).  When let-off occurs, I'd think th= at the hammer head would then catch up with the rest of the shank.... I'm just suggesting this as a possibility.  I claim no extensive kn= owledge of physics..... Dave In a message dated 4/28/03 4:55:01 AM Pacific Daylight Time, imatunr@srv= inet.com writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-= LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Would not that slow down th= e hammer? Joe Goss <A HREF="mailto:imatunr@srvinet.com">imatunr@srvinet.com</A> <A HREF="http://www.mothergoosetools.com/">www.mothergoosetools.com</A= > <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-= LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">----- Original Message ----= - From: <A HREF="mailto:Piannaman@aol.com">Piannaman@aol.com</A> To: <A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A> Sent: Sunday, April 27, 2003 11:32 PM Subject: Re: hammer velocity In a message dated 4/27/03 7:12:21 AM Pacific Daylight Time, <A HREF="= mailto:mjbkspal@execpc.com">mjbkspal@execpc.com</A> writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-= LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Between let-off and impact,= the jack, rep lever, and string are not in contact with the knuckle.  = The list of forces acting on the hammer/shank assembly consists of gravity a= nd center pin.  period.  Both are acting to decelerate the hammer.= </BLOCKQUOTE> Mike, What about the flex of the hammer shank?  When the jack releases, i= t is no longer forcing the shank to flex, thus allowing it to spring back in= to its original form a nano-second before striking the string.  Couldn'= t that cause acceleration of the hammer head?   </BLOC= KQUOTE> </BLOCKQUOTE> </HTML>