<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Making bridges</title></head><body> <blockquote type="cite" cite><font size="-1" color="#000080">Ah, Ron, we can tell you're not a wooden boat builder!</font></blockquote> <div><br></div> <div>That's right, strictly pianos in my case.</div> <div><br></div> <blockquote type="cite" cite><font size="-1" color="#000080">A good scarf joint will equal the strength of a solid wood beam. And it will have a slope of 1:8 (non-structural use) or 1:12 (structural use). </font></blockquote> <div><br></div> <div>Sure, but no one has to my knowledge built pianos bridges with such low scarf angles, since there would be a greater wastage of wood with a lower angle and it is not required from a structural perspective. While I was aware joint strength increases relative to the scarf angle, I felt it appropriate for the sake of brevity not to write a thesis on the matter. My apologies if you felt I didn't address the issue adequately. I mentioned the 1:5 joint as typical because that's what it is typically used in piano bridges.</div> <div><br></div> <blockquote type="cite" cite><font size="-1" color="#000080">The amount of slope also varies with the glueability of the wood being joined. Spruce bonds very easily, maple somewhat less so. Finger-joints, by the way, are simply a form of scarf-joint. In this case the scarfs are made short and are stacked for less wood waste.</font></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font size="-1" color="#000080">We can compromise on the slope of the scarf in the construction of piano bridges because it is a "non-structural" application. The absolute beam strength is not critical.</font></blockquote> <div><br></div> <div>Thank you.</div> <div><br></div> <blockquote type="cite" cite> <font size="-1" color="#000080">Del</font></blockquote> <div><br></div> <div>Ron O.<br> </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>