<DIV>I have carefully checked my Jaras string ht. gauge and it is right on.  I need to come up with a better rig for measuring the flange center pin ht. - something more stable, but I don't think I have a faulty measurement there.  The string rises ( different strings rise at different rates) as it goes toward the bridge.  I have wondered if the action rail could change height in the middle compared to the ends where I measured.  </DIV> <DIV>Humidity changes could cause a very slight change in string ht as the bridge rises but not enough to affect regulation I suppose.  If center rail glides are down to far they could affect flange center pin ht.     </DIV> <DIV> </DIV> <DIV>I bored some new hammers at 48 mm bore distance and they regulated well.  They were able to have 45mm blow, .390 (9.9) dip, and .030 aftertouch.  So, I guess that's the bore distance I'll use.  Thanks for all your help.</DIV> <DIV> </DIV> <DIV>Bob<BR><BR><B><I>David Love <davidlovepianos@earthlink.net></I></B> wrote:</DIV> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">Perhaps your string height measuring device is improperly calibrated. Or,<BR>you measured the flange center pin height incorrectly, or both. The only<BR>other possibility is that the strings run downhill to the bridge by the<BR>amount of the difference. That doesn't seem likely. <BR><BR>David Love<BR>davidlovepianos@earthlink.net<BR><BR><BR>----- Original Message ----- <BR>From: Bob Hull <BR>To: Piano tech<BR>Sent: 8/21/2003 8:03:08 AM <BR>Subject: Re: overcentering justified?<BR><BR><BR>When I measured the distance from the key bed (workbench) to the hammer<BR>flange center pin and subtracted it from the string height near the hammer<BR>strike point, why did it give me a 2" (50.8 mm) difference? This is a<BR>different indication of bore distance from when I put a line level on a<BR>hammer shank and compared a 50.8mm bore distance to a level on the strings.<BR>The 50.8mm bore shows that when the hammer is raised to the string the<BR>bubble indicates a slightly undercentering. The old 48 mm bore shows a<BR>shank that has almost exactly at the same level (slight rise) as the<BR>string. <BR><BR>Since the string ht. was measured at a distance about 130mm (length of<BR>shank to center of hammer molding) away from the center pin ht. it seems<BR>like it should have indicated<BR>the same distance as the level/bubble comparison test. ???<BR><BR>Why didn't it? Any ideas?<BR><BR><BR><BR>_______________________________________________<BR>pianotech list info: https://www.moypiano.com/resources/#archives</BLOCKQUOTE><p><hr SIZE=1> Do you Yahoo!?<br> <a href="http://us.rd.yahoo.com/evt=10469/*http://sitebuilder.yahoo.com">Yahoo! SiteBuilder</a> - Free, easy-to-use web site design software