Bob: I have found it awkward to measure the center pin height as well. The method I now use incorporates the Jaras String height gauge as well. That way, the string height and center pin height are taken with the same measuring device and even if the absolute measurement is off, it is the net difference that counts and it will be correct. To measure the center pin height, place a straightedge along the top of the hammer flanges extending out over the end of the action (I take measurements from both the bass and treble end BTW--sometimes they are different). Now place the Jaras gauge under the straight edge along side the action and take the reading. Then measure the distance from the top of the flange to the center of the center pin and subtract that from your initial measurement. That will be your center pin height. David Love davidlovepianos@earthlink.net ----- Original Message ----- From: Bob Hull To: davidlovepianos@earthlink.net;Pianotech Sent: 8/21/2003 7:19:55 PM Subject: Re: overcentering justified? 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. 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. 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. Bob David Love <davidlovepianos@earthlink.net> wrote: Perhaps your string height measuring device is improperly calibrated. Or, you measured the flange center pin height incorrectly, or both. The only other possibility is that the strings run downhill to the bridge by the amount of the difference. That doesn't seem likely. David Love davidlovepianos@earthlink.net ----- Original Message ----- From: Bob Hull To: Piano tech Sent: 8/21/2003 8:03:08 AM Subject: Re: overcentering justified? When I measured the distance from the key bed (workbench) to the hammer flange center pin and subtracted it from the string height near the hammer strike point, why did it give me a 2" (50.8 mm) difference? This is a different indication of bore distance from when I put a line level on a hammer shank and compared a 50.8mm bore distance to a level on the strings. The 50.8mm bore shows that when the hammer is raised to the string the bubble indicates a slightly undercentering. The old 48 mm bore shows a shank that has almost exactly at the same level (slight rise) as the string. Since the string ht. was measured at a distance about 130mm (length of shank to center of hammer molding) away from the center pin ht. it seems like it should have indicated the same distance as the level/bubble comparison test. ??? Why didn't it? Any ideas? _______________________________________________ pianotech list info: https://www.moypiano.com/resources/#archives Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software
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