<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Unusual rib structure?</title></head><body> <div>Sarah and all,</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">Thanks for the feedback.  Rib crowned?  Interesting.  What characteristics suggest that?</font></blockquote> <div><br></div> <div>From the image, it looked as if the rib depth increased some towards the centre. However your measurements discount this. When the ribs are crowned the desired radius is machined into the top surface of the rib. This will result in a rib which is deeper in the center and shallower at the ends.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1"> I gather that rib crowning is a more recent development in piano technology?</font></blockquote> <div><br></div> <div>I don't know whether any of us can definitively say when rib crowning was first practised, but certainly it is more widely, though by no means universally practised today. Del is probably the best to comment on this, but you can be sure that not all piano makers will have divulged all of their manufacturing processes. The piano you have demonstrates that there are many different approaches out there. No one company or individual has a monopoly on good ideas - contrary to what some may claim.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">Is there some place I could read a brief history?</font></blockquote> <div><br></div> <div>The list archives is probably the best source. The two have most discussed the procedure on this list would be Del and Ron N.</div> <div><br></div> <blockquote type="cite" cite> <font face="Arial" size="-1">I measured the ribs for you.  I wasn't perfectly exact in my measurements (didn't have the time), but if you want more exact measurements, I'll get them for you later. </font></blockquote> <div><br></div> <div>Thank you for your trouble. The measurements you provided are more than adequate.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">Aside from the tapered ends, the dimensions are constant throughout the length of each rib. </font></blockquote> <div><br></div> <div>This would lead me to conclude that the ribs were not crowned. It is possible that they may have planed the ribs to achieve a uniform thickness after assembly, but it would nonetheless be unlikely.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">The bottom of each rib is rounded slightly </font></blockquote> <div><br></div> <div>This is normal.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1"> I didn't measure the lengths of the tapers.  The height and width of the ribs (in mm) are as follows (in order from treble to bass):</font></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">rib    h    w</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">1    difficult access</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">2    19    19</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">3    21    21</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">4    21    23</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">5    25    24</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">6    25    25</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">7    26    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">8    ?    26 (difficult access)</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">9    28    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">10    28    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">11    28    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">12    27    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">13    27    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">14    26    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">15    26    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">16    26    26</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">17   difficult access</font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">18   difficult access</font></blockquote> <div><br></div> <div>So the middle order ribs are quite deep, even for modern piano making standards. Its interesting that they have gone the Bösendorfer Imperial route, by chosing to make the longer ribs wider than they are high (actually 28 w by 26 h is very similar to the Imperial - not a good idea). This will yield a significant mass increase for only moderate gains in rib strength. They would have done better with a height of 28 and width of 26. But so often, piano makers are frightened to step off the beaten path into new territory.</div> <div><br></div> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">You are correct that the bass is rather dark.  Of course I like it that way.</font></blockquote> <div><br></div> <div>Indeed. I find dark toned low basses more interesting than usual fare we get from the current crop of concert grand makers.</div> <div><br></div> <div>Ron O.</div> <x-sigsep><pre>-- </pre></x-sigsep> <div>_______________________<br> <br> OVERS PIANOS - SYDNEY<br> Grand Piano Manufacturers<br> <br> Web: http://overspianos.com.au<br> mailto:info@overspianos.com.au<br> _______________________</div> </body> </html>