<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> Hi Bob... Whilst I understand the usual this and that's about conversions and whatnots.... and I dont mean really criticize or anything... it would be nice if you stuck to either inches or mm for all your measurements... gets a bit confusing especially when reading replies with quotes. I took the liberty of converting them and  inserting in your reply. You changed the bore by just barely under 3 mm and you got Bob Hull wrote: <blockquote TYPE=CITE>David, The old hammers with the bore distance of 48 mm had a blow of 44.5mm and a dip of 11.11 mm to a 10.31mm.  Let off was very close, just backed down enough to not block, drop was a little much - 6.35 mm or more on some.  It plays well and  repeats well with this regulation.  I do not want the dip to be that much with the new hammers, and I want the drop to be tiny.</blockquote> Looks to me like you could have first lowered your blow abit and regulated key dip to around 10 most places... but that's quite the variance in dip you show... not knowing how much aftertouch variance there was makes it a bit hazy to guess at.. but I would suppose that more or less matched the variance in dip. Drop was way to much... and couple with a deep dip suggests to me that both the drop screws were regulated to low and that there wasn't a whale of a lot of aftertouch. If let off was reasonably close to 1.5 mm at the same time then something doesn't seem right. I mean... you had standard D bore length... short blow distance, deep keydip..... at yet little aftertouch for standard let off... Perhaps its just that the drop screw was screwed down so low that real aftertouch is hard to read into this scenario. If on the other hand you had good aftertouch and very close setoff.. you could had probably just regulated closer to specs and came out just fine. Hard in anycase to understand the need to go to a near 51 mm bore distance from this perspective. Having the hammers at exactly 90 degrees to the shank, while at the same time having the shank parallel to the strings is not necessarily a big << musto >> but if you are going to first insure this, then there are a few things you need to insure first before you decide what bore length you need to make that work. David Love covered that well enough including the ref to Bob Hohfs article series. As the thread deals with overcentering... you can allow yourself a couple two three degrees of freedom with the rake of the hammer to achieve a perpedicular to string plane impact angle for the hammer itself. Unless that also means that the shank is very far from level it shouldnt be a real big problem. Just a few thoughts... I havent followed the thread real close so excuse both the intrusion and whatever I may have missed along the way Cheers RicB   <blockquote TYPE=CITE>  In trying to understand your response I may need to clarify: The 41 mm blow I spoke of was what the new hammer with the 2 inch bore (50.8 mm) distance seemed to call for.  I tried to regulate a new hammer with that 50.8 mm bore at 45 mm blow (any more and it was resting on the cushion); 9.9 mm dip, and around .79 mm aftertouch.  I also checked all other regulation areas on this sample.  It would play with these specs but it would not repeat real quickly like another sample that was regulated with a short blow of 41 or 42 mm.  I also regulated the glides on the center rail to make sure key height wasn't being affected by how the old regulation.  I believe the keys were being elevated .5 to 1 mm by glides being turned down too low. The 50.8mm  bore gives me a hammer that is almost exactly level shank, but since the strings are not level I need to match my shank level to them, not just have a bubble that is in in center. you said "use metal washers and raise the stack to the standard bore dimension" - do you mean the 48 mm hammer bore dimension that a Hamburg D calls for?  I am wondering now why my measurement of string height (near the hammer strike point) didn't give me a shank that matched the string angle?  I want to recheck that.  I will work more on try some samples before I plug the new ones and redrill. Thanks, Bob Hull <hr SIZE=1>Do you Yahoo!? <a href="http://us.rd.yahoo.com/evt=10469/*http://sitebuilder.yahoo.com">Yahoo! SiteBuilder</a> - Free, easy-to-use web site design software</blockquote> -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>  </html>