---------------------- multipart/alternative attachment Dale and all, The idea for adding crowned ribs to an existing=20 flat board was entirely the idea of David Kinney. I must admit that when David mentioned that he=20 wanted to add auxiliary ribs, I thought it was so=20 much trouble, and difficult to get them in the=20 high treble, that I felt it would be easier to=20 rip the board out and build another one. But I agreed that if he was prepared to endure=20 such an experiment, that it would certainly be=20 worth a try. He marked out the location areas for=20 the ribs and cleaned off the finish, then wedged=20 the board up using the back braces to=20 approximately match the crown of the machined=20 ribs. The auxiliary ribs were fitted to the board=20 by screwing them through the panel. After the=20 glue dried he removed the screws and doweled the=20 hole using hammer shank. I haven't seen the piano yet. But everything=20 David does is executed to the highest standards.=20 So you can be sure that the work will look very=20 tidy. I'll be travelling to his home workshop (1.5 hrs=20 west into the mountains from Sydney) to see the=20 piano as soon as the action is done. I'll forward=20 a report to the list once I've seen and heard it. Best, Ron O. PS. A few responses to Dale's post below. > Great post. my cup o tea > I'm Interested in the Mechanics of how this=20 >was accomplished with the board still in the=20 >piano. Ie. How were these ribs attached ?=20 >Removing the old finish neatly to get a good=20 >glue bond ?how you determined the size & height=20 >of ribs & what consideration did you give to the=20 >effects of the old ribs that were flattened and=20 >pulling the crown down. The height and width of the ribs was determined=20 by the physical space available regarding height.=20 The width of 15 mm was arrived at after=20 considering the two conflicting interests of=20 making them as thin as possible to reduce the=20 added weight, while providing sufficient gluing=20 area to ensure a successful joint. After some=20 discussion we arrived at 30 mm deep by 15 mm wide. > I assume this is a CC board to begin with. It would largely have been CC, although I=20 understand that B=F6sendorfer do crown their ribs,=20 so it may well have been a combo CC part Rib=20 supported. >Putting on new finish with beams and all in the way. Yes I know, what a pain. >Pictures would be facinating. David's got a Canon 300D, so I'm sure he won't=20 mind taking a few images once its all done. I=20 could post them to our website for all to see. > Very interesting experiment. Resourceful & I might add clever thinking. > Dale > >Hello all (and Dale, who I've CC'd since he could be off list at present) > >A re-crowning exercise. > >A local colleague, David Kinney, is currently=20 >rebuilding a B=F6sendorfer (late-ish model 200,=20 >about 20 year old example I think). The sound=20 >board was collapsed but otherwise without any=20 >visible panel defects. As an exercise in sound=20 >board re-crowning, he commissioned us to build=20 >him a set of crowned sitka ribs for fitting in=20 >between the originals. We made them 30 mm high=20 >in the middle by 15 mm wide, so as to maximise=20 >the added stiffness without adding too much=20 >weight to the board. We made them only long=20 >enough to match the un-feathered lengths of the=20 >adjacent original ribs > >I understand that the result is very successful.=20 >After doing the usual total internal refinish he=20 >has reset the down bearing throughout, which=20 >required a considerable packing height for most=20 >string sections. He says that about 50% of the=20 >unstrung downbearing angle sunk out once the=20 >piano was pulled to pitch, which is about on par=20 >with new factory boards. I haven't heard the=20 >piano yet as he is still doing the action. It'll=20 >be interesting to hear it once its up and=20 >running. > >Ron O. > > -- OVERS PIANOS - SYDNEY Grand Piano Manufacturers _______________________ Web http://overspianos.com.au mailto:ron@overspianos.com.au _______________________ ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/37/b0/6e/78/attachment.htm ---------------------- multipart/alternative attachment--
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