<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Thanks for your input Ron. Comments below:<div><br></div><div>Terry Farrell</div><div><br><div><div>On Nov 2, 2012, at 9:10 AM, Ron Nossaman wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>On 11/2/2012 7:30 AM, Terry Farrell wrote:<br><br><blockquote type="cite">To the best of my knowledge, it seems to me that the hammer boring<br></blockquote><blockquote type="cite">for an American square grand piano (or any piano) should result in<br></blockquote><blockquote type="cite">the diameter axis of each hammer either being parallel to its<br></blockquote><blockquote type="cite">respective string(s), or if not parallel, then purposely angling the<br></blockquote><blockquote type="cite">hammer diameter axis a few degrees toward parallel with the hammer<br></blockquote><blockquote type="cite">shank. Is that correct? Should hammers be bored so that there is<br></blockquote><blockquote type="cite">always some appropriate bias toward the hammer diameter axis being<br></blockquote><blockquote type="cite">more parallel with the hammer shank?<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">That's what I observe on all vertical and modern grand pianos, and<br></blockquote><blockquote type="cite">makes sense for clearance. I believe the same applies to a square<br></blockquote><blockquote type="cite">grand.<br></blockquote><br>Well, I'm not an action designer, but I'm a fair to middlin' mechanic. Look at the difference between the angles of the strings to the shanks between modern pianos and that square. You have a whole different world there, and nothing you do will make it work like a modern piano, or even an intelligently designed mechanism. </div></blockquote><div><br></div><div>Absolutely. I'm in full agreement there.</div><br><blockquote type="cite"><div>Compare the old hammers with the new and see how the angles match. If they do, they aren't mis-bored. </div></blockquote><div><br></div><div>Well, therein lies part of the problem. Hammers were replaced some decades ago with a set of hammers that were bored and shaped by a kindergarten arts & crafts class. The new ones are pretty close to the bad old replacements, but I assumed (yeah, I know) that the boring would be based on the string grooves, not the replacement boring. That appears to be where the improperly bored angles come from.</div><br><blockquote type="cite"><div>If they aren't mis-bored, rejoice that you don't have to learn the hard way from scratch what they need to be to work.<br></div></blockquote><div><br></div><div>So, it appears that I do have to learn the hard way from scratch what they need to be to work. And hence, the question.</div><br><blockquote type="cite"><div><blockquote type="cite">On the <font class="Apple-style-span" color="#9d1e8f">(new)</font> set I have, the bass hammers are close to parallel with their</blockquote><blockquote type="cite">respective bass strings, but starting in the low tenor and going up<br></blockquote><blockquote type="cite">the scale, the hammers start to diverge from being parallel with<br></blockquote><blockquote type="cite">their respective strings, but the deviation from parallel with the<br></blockquote><blockquote type="cite">respective strings is toward the diameter axis of the hammer being<br></blockquote><blockquote type="cite">perpendicular to the hammer shank - not parallel with the hammer<br></blockquote><blockquote type="cite">shank. I'm sure you can easily imagine what kind of hammer clearance<br></blockquote><blockquote type="cite">problems that produces.<br></blockquote><br>The clearance problems should be worst in the bass and low to mid tenor. </div></blockquote><div><br></div><div>Right. But that's not what's happening because the bass are bored so the hammers are parallel with the bass strings (no deviation), but in the mid tenor, where the strings are more parallel with the shanks, the hammer boring makes the hammers not parallel with the strings, but the hammer angles deviate toward being more perpendicular to the shanks than the string angles.</div><br><blockquote type="cite"><div>Depending on the bore angle, your choice is between only hitting one unison with the hammer, or having them clear one another. Theoretically, there is a compromise where each is possible, if you squint just right and are good with a sharp knife and sanding paddle.<br><br>At the absolute very best, the hammers BARELY clear and BARELY miss adjacent unisons. Plan on being there for a while. Except for certain pathological cases, aversion therapy works!<br></div></blockquote><div><br></div></div>I agree wholeheartedly with all that. But I still have the basic question:  Assuming I am thinking clearly here, what kind of maximum bias toward parallel with shank from parallel with strings is appropriate? I realize you can't go too far because you want the hammer contact point to be close to a line at the apex of the hammer, but how far is too far (assuming the hammer doesn't end up hitting something else)?</div><div><br></div><div>I guess I'm looking for a number, if there is any, that would apply to a normal piano action (not a square). I know I will have to use that kind of information and see how it might apply to my square grand. I know that no one is going to give me a number for the square. But maybe my most basic question is this: the existing hammers in the tenor are bored so the hammers are about 10 degrees toward perpendicular to the shanks from parallel with the respective strings. My common sense tells me this is WRONG - plain flat wrong. My common sense tells me hammers should be parallel with the strings where clearance allows, or angled slightly toward parallel with respective strings to improve clearance. I'm hoping that some background on how designers choose hammer boring angles in normal pianos will help guide me in my quest to make some intelligent decisions on my square.</div><div><br></div><div>Thanks so much for sharing your thoughts.</div><div><br></div><div>Terry Farrell</div></body></html>