<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Capo Hardening, was: Tuning problems under capo ba</title></head><body> <div>At 1:27 AM -0500 25/1/03, Sarah Fox wrote:</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">I've wondered about this myself.  My Wissner's capo is very badly grooved.  I've shifted some of the strings slightly to eliminate their "zinging," but the capo will obviously need reshaping.</font></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">As far as I'm aware, different metals are hardened via different methods.  However, the fact remains that this usually involves heating and cooling for various periods of time -- something that's hard to do with something as large as a harp -- and difficult to do without stressing the metal and risking a crack.</font></blockquote> <blockquote type="cite" cite> </blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">I believe some ferrous alloys are hardened with magnetic fields,</font></blockquote> <div><br></div> <div>The process is called induction hardening. It is very effective since the depth of hardening can be controlled by the frequency of the magnetic field.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">perhaps with moderate heating.  Perhaps this could be a useful alternative?  I have no idea how this is done, though.</font></blockquote> <div><br></div> <div>An induction coil has to be constructed such that the desired magnetic field is developed where it is required.</div> <div><br></div> <blockquote type="cite" cite> <font face="Arial" size="-1">Alternatively, does anybody ever grind the original capo off and overlay a hardened bar, fitted for height? </font></blockquote> <div><br></div> <div>We do this all the time with the front duplex bars, you can place them in best position for de-tuning and at the shortest possible length. The Steinway D we did late last year has the cleanest treble we've ever heard on a D. I ground the original duplex bars off and filled the plate topography with body filler before positioning the bars. Looks very tidy and I like to clarity now.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">It could be epoxied in place for a tight mechanical contact. </font></blockquote> <div><br></div> <div>There's enough down force from the string angle of turn over the bar.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">Of course this begs the question of what happens when a capo is ground and filed and ground and filed and ground and files -- until the downbearing is inadequate. </font></blockquote> <div><br></div> <div>Once the bar is hardened once, if it is done properly, the bar never deforms again. Furthermore, after six years of commercial service they tune as if they were restrung the week before.</div> <div><br></div> <div>Ron O.</div> <div><br></div> <div><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>