<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Sound board trenching and stuff</title></head><body> <div>Hi all,</div> <div><br></div> <div>A couple of weeks ago (can't remember the name of the thread or to which list it was posted), Dean May floated the idea of trenching the sound board at the rear, adjacent to A1, as an alternative means to cutting a full soundboard float.</div> <div><br></div> <div>As someone responded to Dean's suggestion, we've been trenching boards for many years now (since about the mid 90's). Seiler have been trenching the entire sound board perimeter for even longer. We tried this also, but after a serious of experiments over several years the idea has evolved to that which you see below. This image is of a Kawai KG6 that we're rebuilding at the moment. The trench depth is 5 mm, half that of the panel thickness. We fitted rib extensions and re-crown the board, fitted an Overs action and are in the process of a full refinish. We've kept the original bridges, even though the long bridge is a little lower than my preference. We've re-cut the notching and refinished the board. The plugged perimeter bolt hole (to the left of image) is a consequence of the Oak rim in these early KG series pianos. Oak is a good wood for rims but it is prone to corroding the fittings. Its not usual to twist off two or three perimeter bolts when removing a KG plate (we replace the original bolts with heavier gauge zinc plated coach bolts - with dome nuts fitted for looks - to avoid getting cursed-in-the-box sometime mid century). Normally, if replacing a board, we would use the Baldwin plate mounting system. But when re-crowning an existing board we leave the original plate mounting dowels in place. We typically will need to pack the stringing pillows by up to 5 mm at the mid-board area to establish a workable down bearing with a re-crowned panel.</div> <div><br></div> <div>I've taken a series of images of the re-crowning process for this rebuild. I'm putting them together for a class I'm giving in Auckland on the 29th. The New Zealand branch of the APTTA is holding a mini-convention in Auckland on Oct 29 and 30. Anyone feeling like a tax deductible weekend in New Zealand?</div> <div><br></div> <div>Ron O.</div> <div><br></div> <div><img src="cid:a06110427bf774601661b@[10.0.0.72].1.0"></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>