<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Increasing Crown</title></head><body> <div>Dale and all,</div> <div><br></div> <div>The idea for adding crowned ribs to an existing flat board was entirely the idea of David Kinney.</div> <div><br></div> <div>I must admit that when David mentioned that he wanted to add auxiliary ribs, I thought it was so much trouble, and difficult to get them in the high treble, that I felt it would be easier to rip the board out and build another one.</div> <div><br></div> <div>But I agreed that if he was prepared to endure such an experiment, that it would certainly be worth a try. He marked out the location areas for the ribs and cleaned off the finish, then wedged the board up using the back braces to approximately match the crown of the machined ribs. The auxiliary ribs were fitted to the board by screwing them through the panel. After the glue dried he removed the screws and doweled the hole using hammer shank.</div> <div><br></div> <div>I haven't seen the piano yet. But everything David does is executed to the highest standards. So you can be sure that the work will look very tidy.</div> <div><br></div> <div>I'll be travelling to his home workshop (1.5 hrs west into the mountains from Sydney) to see the piano as soon as the action is done. I'll forward a report to the list once I've seen and heard it.</div> <div><br></div> <div>Best,</div> <div>Ron O.</div> <div><br></div> <div>PS. A few responses to Dale's post below.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" color="#000000">  Great post. my cup o tea</font></blockquote> <blockquote type="cite" cite><font face="Arial" color="#000000">   I'm Interested in the Mechanics of how this was accomplished with the board still in the piano. Ie. How were these ribs  attached ? Removing the old finish neatly to get  a good glue bond ?how you determined the size & height of ribs & what consideration did you give to the effects of the old ribs that were flattened and pulling the crown down.</font></blockquote> <div><br></div> <div>The height and width of the ribs was determined by the physical space available regarding height. The width of 15 mm was arrived at after considering the two conflicting interests of making them as thin as possible to reduce the added weight, while providing sufficient gluing area to ensure a successful joint. After some discussion we arrived at 30 mm deep by 15 mm wide.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" color="#000000"> I assume this is a CC board to begin with.</font></blockquote> <div><br></div> <div>It would largely have been CC, although I understand that Bösendorfer do crown their ribs, so it may well have been a combo CC part Rib supported.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" color="#000000">Putting on new finish with beams and all in the way.</font></blockquote> <div><br></div> <div>Yes I know, what a pain.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" color="#000000">Pictures would be facinating.</font></blockquote> <div><br></div> <div>David's got a Canon 300D, so I'm sure he won't mind taking a few images once its all done. I could post them to our website for all to see.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" color="#000000">  Very interesting experiment. Resourceful & I might add clever thinking.</font></blockquote> <blockquote type="cite" cite><font face="Arial" color="#000000">  Dale</font><br> <font face="Arial" size="-1" color="#000000"></font> <blockquote><font face="Arial" size="-1" color="#000000">Hello all (and Dale, who I've CC'd since he could be off list at present)</font></blockquote> <blockquote align="center"><font face="Arial" size="-1" color="#000000"><b><br></b></font></blockquote> <blockquote align="center"><font face="Arial" size="-1" color="#000000"><b>A re-crowning exercise.</b></font></blockquote> <blockquote><font face="Arial" size="-1" color="#000000"><br></font></blockquote> <blockquote><font face="Arial" size="-1" color="#000000">A local colleague, David Kinney, is currently rebuilding a Bösendorfer (late-ish model 200, about 20 year old example I think). The sound board was collapsed but otherwise without any visible panel defects. As an exercise in sound board re-crowning, he commissioned us to build him a set of crowned sitka ribs for fitting in between the originals. We made them 30 mm high in the middle by 15 mm wide, so as to maximise the added stiffness without adding too much weight to the board.  We made them only long enough to match the un-feathered lengths of the adjacent original ribs</font></blockquote> <blockquote><font face="Arial" size="-1" color="#000000"><br></font></blockquote> <blockquote><font face="Arial" size="-1" color="#000000">I understand that the result is very successful. After doing the usual total internal refinish he has reset the down bearing throughout, which required a considerable packing height for most string sections. He says that about 50% of the unstrung downbearing angle sunk out once the piano was pulled to pitch, which is about on par with new factory boards. I haven't heard the piano yet as he is still doing the action. It'll be interesting to hear it once its up and running.</font></blockquote> <blockquote><font face="Arial" size="-1" color="#000000"><br></font></blockquote> <blockquote><font face="Arial" size="-1" color="#000000">Ron O.</font><br> <font face="Arial" size="-1" color="#000000"></font></blockquote> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1" color="#000000"> </font></blockquote> <div><br></div> <div><br></div> <x-sigsep><pre>-- </pre></x-sigsep> <div><font face="Times New Roman" size="+1" color="#0000FF"><b>OVERS PIANOS - SYDNEY</b></font></div> <div><font color="#000000"><i>   </i></font><font color="#0000FF"><i>Grand Piano Manufacturers</i></font><font color="#000000"><br> _______________________</font></div> <div><font size="-2" color="#000000"><br> </font><font color="#000000">Web http://overspianos.com.au</font></div> <div><font color="#000000">mailto:ron@overspianos.com.au<br> _______________________</font></div> </body> </html>