<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <TITLE>Message</TITLE> <META content="MSHTML 6.00.2900.2838" name=GENERATOR></HEAD> <BODY style="WORD-WRAP: break-word; khtml-nbsp-mode: space; khtml-line-break: after-white-space"> <DIV><SPAN class=864395615-30032006><FONT color=#000080>Wim,</FONT></SPAN></DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080></FONT></SPAN> </DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080>I would submit to you that the glue never lets go or moves - I think that when you heat the glue joint and twist the hammer, you are actually twisting the shank wood.  Unless you have just glued the shanks on in the past few hours, there is not enough moisture in the glue or shank to soften the glue up enough.</FONT></SPAN></DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080></FONT></SPAN> </DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080>The tip of the shank is usually the thinnest point, so the hammer is easiest to twist at this location, which I think is why it feels like the hammer is spinning on the shank.  When heating the full shank length, though, the twisting is spread out over a longer area.  I don't have any kind of definitive test results that say heating the full shank is more stable, but that has been my impression.</FONT></SPAN></DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080></FONT></SPAN> </DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080>If you have a suitable test hammer I'd be interested in hearing if you can continue to rotate the hammer - If I am wrong about this I'd like to know, as I have tried loosening hammer glue joints with heat alone and have never succeeded.  If the glue has actually loosened enough to allow the hammer to spin, then there would be nothing stopping it from spinning on around.  Give it a try.  Also, try a thumb nail into the glue collar after you heat it - does it feel soft?  Wood glues might.</FONT></SPAN></DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080></FONT></SPAN> </DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080>My understanding is that heating the wood temporarily softens the resins in the wood, allowing it to twist.  Once it cools back down the resins harden again, and the fibers are locked into place.  Humidity swings can affect the results, of course, but then humidity swings can affect the shanks in any case, whether they have been twisted or not.  If the fibers have been seriously twisted (more than 5 degrees??) it seems logical that they would be exerting more restoring force, and the wood resins might allow creep during high temperature / high humidity conditions.  Over-heating the shanks to the point where they begin to turn black is a bad thing - the resins are cooked, and will not be as resilient, changing the shank flexibility and strength.</FONT></SPAN></DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080></FONT></SPAN> </DIV> <DIV><SPAN class=864395615-30032006><FONT color=#000080>Don Mannino RPT</FONT></SPAN></DIV> <DIV><FONT color=#000080></FONT> </DIV> <BLOCKQUOTE dir=ltr style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000080 2px solid; MARGIN-RIGHT: 0px"> <DIV><BR> <DIV> <DIV>On Mar 29, 2006, at 6:38 PM, <A href="mailto:Wimblees@aol.com">Wimblees@aol.com</A> wrote:</DIV><BR class=Apple-interchange-newline> <BLOCKQUOTE type="cite"><FONT id=role_document face=Arial color=#000000 size=2> <DIV> <DIV>In a message dated 3/29/2006 1:17:00 PM Central Standard Time, <A href="mailto:garym@PIANOSERVICE.BIZ">garym@PIANOSERVICE.BIZ</A> writes:</DIV> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>I used to heat the glue joint to align hammers, until I found out that Titebond begins to break down at about 120 degrees, and loses half its strength at about 150 degrees. I got this info from a technician named Tom Patten in his class concerning fire damage to pianos. My understanding is he got this information from Franklin, the makers of Titebond. I assume this applies to other glues as well.</FONT></BLOCKQUOTE></DIV> <DIV></DIV> <DIV>It would be interesting to see how hot the glue joint becomes. I use a Weller heat gun, and put the nozzle about 2" or 3" from the glue joint. Then I do as Ed does, although I don't hold on to the shank with pliers. I sort of "swipe" at the glue joint until I can feel the hammer move. After all, in most cases, we're only talking moving the hammer one or two degrees, so it is not going to take much heat to loosen the glue joint. </DIV> <DIV> </DIV> <DIV>Wim </DIV></FONT></BLOCKQUOTE></DIV><BR></DIV></BLOCKQUOTE></BODY></HTML>