<br><br><div class="gmail_quote">On Sat, Dec 1, 2012 at 8:36 AM, Dale Erwin <span dir="ltr"><<a href="mailto:erwinspiano@aol.com" target="_blank">erwinspiano@aol.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <font color="navy" face="Comic Sans MS, sans-serif"><font color="#000080" face="Comic Sans MS, sans-serif"> At some point my eyes kind of glaze over with splittin hairs on certain things and this is one. </font></font></blockquote> <div><br>Agreed, Dale. <br><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"><font color="#000080" face="Comic Sans MS, sans-serif">So I see it this way thru my smoke and mirrors.</font> <div><font><font color="#000080" face="Comic Sans MS, sans-serif">The inner rim has an approx 1 1/2 degree bevel cut into the inner rim at the factory. Set a straight edge on it & it becomes apparent.</font></font></div> <div><font><font color="#000080" face="Comic Sans MS, sans-serif"> We have a soundboard, be it rib crowned or other wise crowned. I don't care. It is dome shaped. </font></font></div></font></blockquote><div> </div> <div>Agreed; though at first, coming out of the rib press, whatever that may be, the board and rib assembly is more channeled across the panel grain than dome-shaped over all. Gluing on the bridge (assuming the bridge is hollowed underneath, as most are) begins the process of forming the dome, but it is after gluing to the rim that the board and rib assembly takes on a more decidedly domical shape than channeled. <br> <br>The shape of a dome is exceedingly rigid for its light weight. A clear advantage for our needs. A dome is a three-dimensional support system. A beam, whether crowned or not is the first dimension, a legitimate arch is the second (channeled) and the dome being the third (take an arch and spin it and you have a dome). With each successive progression from beam to dome comes order of magnitude load-resisting capabilities. <br> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"><div><font><font color="#000080" face="Comic Sans MS, sans-serif">So it has an angle at the edges. or...said another way...It is not flat. It rises in elevation from </font><font color="#000080" face="Comic Sans MS, sans-serif">the</font><font color="#000080" face="Comic Sans MS, sans-serif"> edge to the highest point in the board. So whats wrong with having an approximation of that angle cut into the inner rim which will match the rise in elevation of the board in some approximation. </font></font></div> </font></blockquote><div><br>Agreed. This reality, it seems to me, should not even be in question. Though, to be clear, the "highest point in the board" would actually exist below the point that would be established by a 1.5 degree rim angle, given that that a linear uphill rise off the rim would not begin to round off and slope downward as would the curve of a soundboard, be it a circle or parabola or whatever.<br> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"> <div><font color="#000080" face="Comic Sans MS, sans-serif">Not a damn thing and n</font><span style="color:rgb(0,0,128);font-family:'Comic Sans MS',sans-serif;font-size:small">ot everyone in a factory who ever designed a piano their way is an idiot Ron. </span></div> <div><span style="color:rgb(0,0,128);font-family:'Comic Sans MS',sans-serif;font-size:small"> </span></div> <div><font color="#000080" face="Comic Sans MS, sans-serif">For what its worth I have glued in several boards to inner rims that were cut flat and it does indeed flatten out the board a little. \</font></div></font></blockquote> <div><br>For sure.<br> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"><div><font color="#000080" face="Comic Sans MS, sans-serif">I'd prefer that not to happen. Do I cut the rim trying to match some idealized rise in elevation. </font></div> </font></blockquote><div><br>Technically and geometrically, the rim angle would have to change in direct proportion to the rib length (or for that matter to the constantly varying cross-grain length of the panel). Shorter ribs form less angle at their ends. This would be a difficult process to achieve and would be, in my view, a waste of time. Given that the shorter ribs imply less of a required angle at the rim, if the rim is angled / beveled at a more or less constant 1.5 degree, the shorter ribs would have to pressed down into the rim "pocket" as these would not normally mate, the rim angle being deeper than the angle naturally formed at the end of the rib / board. I prefer more than less, the 1.5 degree angle being a minimum. No harm done, and only an advantage to be gained. Interestingly, increasing or assuring the rim angle is fairly easily accomplished with a small red devil handled scraper. We do it here all the time. See <a href="http://www.amazon.com/dp/B001SBJIC6/ref=asc_df_B001SBJIC62286157?smid=AXPVI82I57KZA&tag=sdcbing4-20&linkCode=asn&creative=395105&creativeASIN=B001SBJIC6">http://www.amazon.com/dp/B001SBJIC6/ref=asc_df_B001SBJIC62286157?smid=AXPVI82I57KZA&tag=sdcbing4-20&linkCode=asn&creative=395105&creativeASIN=B001SBJIC6</a> for the scraper. When sharp, this tool is amazing.<br> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"><div><font color="#000080" face="Comic Sans MS, sans-serif">No. A waste of time. But to be sure.... No one would want the inner rim to be beveled in the opposite direction. Would they?</font></div> </font></blockquote><div><br>Right.<br> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"><div><font color="#000080" face="Comic Sans MS, sans-serif">jeez</font></div> </font></blockquote><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="navy" face="Comic Sans MS, sans-serif"> <div><font color="#000080" face="Comic Sans MS, sans-serif"><font>Dale</font><br> </font><br> <div style="color:navy;font-family:'Comic Sans MS',sans-serif;font-size:10pt;clear:both"><font color="royalblue" size="1"><b><font face="Georgia, Times New Roman, Times, Serif"><font color="black"><font color="mediumblue" face="Comic Sans MS, sans-serif">Dale Erwin R.P.T.<br> <font color="green">Erwin's Piano Restoration Inc.</font><br> </font></font></font></b></font><font color="darkgreen"><span style="font-style:italic"><b><font size="1"><font color="black" size="1"><font color="blueviolet"><font color="black"> <font color="black" face="Comic Sans MS, sans-serif">Mason & Hamlin</font><font face="Comic Sans MS, sans-serif">/Steinway/</font><font color="black" face="Comic Sans MS, sans-serif">U.S. pianos</font><font face="Comic Sans MS, sans-serif"><br> </font></font></font></font><font color="cornflowerblue" face="Comic Sans MS, sans-serif" size="1"><a href="http://www.Erwinspiano.com" target="_blank">www.Erwinspiano.com</a></font><font size="1"><br> </font><font color="crimson" face="Comic Sans MS, sans-serif" size="1">Phone: <a href="tel:209-577-8397" value="+12095778397" target="_blank">209-577-8397</a></font><br> <font color="darkgreen"></font></font></b></span></font><tt><tt><font color="darkgreen"><br> </font><br> <font></font></tt></tt><br> <br> </div> <br> <br> <div style="font-size:10pt;font-family:arial,helvetica">-----Original Message-----<br> From: Jim Ialeggio <<a href="mailto:jim@grandpianosolutions.com" target="_blank">jim@grandpianosolutions.com</a>><br> To: pianotech <<a href="mailto:pianotech@ptg.org" target="_blank">pianotech@ptg.org</a>><br> Sent: Sat, Dec 1, 2012 7:17 am<br> Subject: [pianotech] Belly talk<br> <br> <div style="font-size:12px;font-family:Tahoma,Verdana,Arial,Sans-Serif;margin:0px"> <pre style="font-size:9pt"><tt>Right... Regarding the "rasten", I'd like to take a step back, and come at this from a "what is physically possible" perspective. For the moment lets leave all design intent aside and look at this from a what is physically possible perspective. The question is "what are rebuilders actually achieving when they do this, as opposed to what do they think they are achieving". To be clear, I'm not talking about tonal results here. I'm simply talking about whether, if one of us said they were going to bevel so-and-so piece of wood at such-and such angle, they actually did what they set out to do...ie the "as built" wooden joint matched their intent. As someone with a background in setting up production runs where hundreds of 5 surface profiled joints had to fit dead nuts without hand adjustment, I had to learn how to prove what I was actually achieving in a particular process rather than assuming that I had achieved what I set out to achieve, wished to achieve, or though I achieved. Learning how to prove the "as built" conditions is a challenging task, much harder than one would expect, until one learns how to create and maintain trustworthy indexes. For any of us the "as built" and the intent can sometimes be wildy different things. Further, its hard enough to match intent to result in set ups where the parts are all straight lines, but with a piano where straight lines are few and far between, and joints are cut in tough to access places, its a whole other kettle of fish. I find this tug between intent and achieved results again and again in piano work. In this work the tug is accentuated because there simply is not a trustworthy reference point or index surface to be had, unless one purposely sets out to create and prove one, and then refer and correct all work back to that known index. So my take on this is, given my background, simply that the mating angle at the "rasten" is highly variable both from the rim's and the panel's perspective and thus unknown in its "as built" reality. At least from a rebuilder's perspective, the rasten joint is physically impossible to actually achieve with the intent techs claim they are shooting for. It only introduces complexity where the complexity takes on a mind of its own. I see the added complexity trying to control such a miniscule detail becoming gratuitous, and even worse fueling speculations about what one achieved without proving that one actually created the intended physical joint. This in addition to whether there is any tonal advantage at all in theory. However this is hypothetical anyway, because probably its never actually been accomplished. Add to this, that the majority of the "rasten" is along the short extremely flexible grain of the panel, and the claims of its value become more and more questionable. Jim Ialeggio -- Jim Ialeggio <span class="HOEnZb"><font color="#888888"><a href="mailto:jim@grandpianosolutions.com" target="_blank">jim@grandpianosolutions.com</a> <a href="tel:978%20425-9026" value="+19784259026" target="_blank">978 425-9026</a> Shirley Center, MA </font></span></tt></pre> </div> </div> </div> </font></blockquote></div><br><br clear="all"><br>-- <br>Nick Gravagne, RPT<br>AST Mechanical Engineering<br>