<table cellspacing="0" cellpadding="0" border="0"><tr><td valign="top" style="font: inherit;"><div>David, I'd like to point out that the type of iron in a Mason plate may also have a bearing on the nearly unique tone. The only one I've busted up (an 1890's upright destroyed by mice) was quite different from any plate I've smashed. It was very thick, but also very "clay like" (smashed into pieces so easily, that I was shocked!) I assume that this grade of iron was chosen for its exceptional acoustical "deadness" (minimal resonance with partials) but cast extra-thick to make up for its relative lack of strength. (I'm just offering this info, in case it may be of some help in your calculations.) Thumpe</div></td></tr></table> <div id="_origMsg_"> <div style="font-family:arial, helvetica, sans-serif:font-size:10pt"> <div style="font-family:times new roman, new york, times, serif;font-size:12pt"> <hr size="1"> From: David Love <davidlovepianos@comcast.net>; To: <pianotech@ptg.org>; Subject: Re: [pianotech] cutting down a MH bridge Sent: Thu, Nov 1, 2012 11:06:50 PM <table cellspacing="0" cellpadding="0" border="0"> <tbody> <tr> <td valign="top" style="font:inherit;"><div class="WordSection1">The bridge adds stiffness and mass to the system which raises the impedance.  I think it raises the impedance too much on those pianos because that’s what I hear.  I don’t really calculate the bridge contribution to the system but I have a preferred minimum and maximum based on my own experience.  The MH bridge exceeds my preferred maximum and the sound that I hear reflects that.      I suppose bridge characteristics can vary with ribs, panel thickness (and scales, for that matter) but I don’t think you should substitute bridge height for rib dimensions or panel thickness.   For me, rib scales and panel thickness are related to string scale (downbearing), size of the piano, number of ribs (of course), .  I don’t really see that the bridge should vary that much.  I think you will get different answers from different people as to what they think is the best combination for the treble bridge based on their own tonal preference and where in the treble bridge you are talking about.     This piano (MH)  has a bridge that at C88 is 40 mm wide and 37 mm tall.  Compare that with a Steinway B also in my shop now that has  abridge that is 33 mm wide and 30 mm tall.  I would say that the difference in bridge dimensions will account for some tonal differences.   The MH has a slightly higher tension scale  but not enough to explain the need for a bridge that much larger.   Of course, you can make a system which is too high in impedance any number of ways: ribs, panel, bridge.  But there probably is some ideal combination.  So far, left to my own devices, I prefer a bridge of somewhat smaller dimensions.  My method of calculating rib scales is not, or at least I prefer that not be, bridge dependent.      <div>David Lovewww.davidlovepianos.com</div>  <div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in;'>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of Encore Pianos Sent: Thursday, November 01, 2012 3:31 PM To: pianotech@ptg.org Subject: Re: [pianotech] cutting down a MH bridge</div></div>  How does it raise the impedence characteristics too much?   Why do you think it raises the impedence characteristics too much?   How much is too much and how much is just enough?   Since we are dealing with mass and stiffness, what would be the best combination for a treble bridge?  Should those characteristics for a bridge vary from piano to piano, depending on the ribbing, panel thickness, etc. etc.?  Will Truitt      <div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in;'>From: <a rel="nofollow" ymailto="mailto:pianotech-bounces@ptg.org" target="_blank" href="javascript:return">pianotech-bounces@ptg.org</a> [<a rel="nofollow" ymailto="mailto:pianotech-bounces@ptg.org" target="_blank" href="javascript:return">mailto:pianotech-bounces@ptg.org</a>] On Behalf Of David Love Sent: Thursday, November 01, 2012 6:08 PM To: <a rel="nofollow" ymailto="mailto:pianotech@ptg.org" target="_blank" href="javascript:return">pianotech@ptg.org</a> Subject: Re: [pianotech] cutting down a MH bridge</div></div>  I didn’t state but I have always felt that the MH bridge was too massive and raised the impedance characteristics too much.   David Love<a rel="nofollow" target="_blank" href="http://www.davidlovepianos.com">www.davidlovepianos.com</a>  <div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in;'>From: <a rel="nofollow" ymailto="mailto:pianotech-bounces@ptg.org" target="_blank" href="javascript:return">pianotech-bounces@ptg.org</a> [<a rel="nofollow" ymailto="mailto:pianotech-bounces@ptg.org" target="_blank" href="javascript:return">mailto:pianotech-bounces@ptg.org</a>] On Behalf Of Dale Erwin Sent: Thursday, November 01, 2012 2:33 PM To: <a rel="nofollow" ymailto="mailto:pianotech@ptg.org" target="_blank" href="javascript:return">pianotech@ptg.org</a> Subject: Re: [pianotech] cutting down a MH bridge</div>  Did I miss why you want to cut it down /remove mass<div>Dale Erwin R.P.T. Erwin's Piano Restoration Inc. Mason & Hamlin/Steinway/U.S. pianos <a rel="nofollow" target="_blank" href="http://www.Erwinspiano.com">www.Erwinspiano.com</a> Phone: 209-577-8397 <tt> </tt> <tt>  </tt></div>  <div>-----Original Message----- From: David Love <<a rel="nofollow" ymailto="mailto:davidlovepianos@comcast.net" target="_blank" href="javascript:return">davidlovepianos@comcast.net</a>> To: pianotech <<a rel="nofollow" ymailto="mailto:pianotech@ptg.org" target="_blank" href="javascript:return">pianotech@ptg.org</a>> Sent: Thu, Nov 1, 2012 12:45 pm Subject: Re: [pianotech] cutting down a MH bridge<div id="AOLMsgPart_0_8203852f-8eea-4fcc-9947-4f9b14417664"><pre style='background:white;'><tt>Or possibly a router.  I was trying to figure out how to build and position</tt></pre><pre style='background:white;'><tt>a guide so as to keep the cut a constant width through the curves without</tt></pre><pre style='background:white;'><tt>having to freehand it.  </tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>David Love</tt></pre><pre style='background:white;'><tt><a rel="nofollow" target="_blank" href="http://www.davidlovepianos.com">www.davidlovepianos.com</a></tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>-----Original Message-----</tt></pre><pre style='background:white;'><tt>From: <a rel="nofollow" ymailto="mailto:pianotech-bounces@ptg.org" target="_blank" href="javascript:return">pianotech-bounces@ptg.org</a> [<a rel="nofollow" ymailto="mailto:pianotech-bounces@ptg.org?" target="_blank" href="javascript:return">mailto:pianotech-bounces@ptg.org</a>] On Behalf</tt></pre><pre style='background:white;'><tt>Of Terry Farrell</tt></pre><pre style='background:white;'><tt>Sent: Thursday, November 01, 2012 12:06 PM</tt></pre><pre style='background:white;'><tt>To: <a rel="nofollow" ymailto="mailto:pianotech@ptg.org" target="_blank" href="javascript:return">pianotech@ptg.org</a></tt></pre><pre style='background:white;'><tt>Subject: Re: [pianotech] cutting down a MH bridge</tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>I'll second what Ron said. And if you do go that route, I know a guy in</tt></pre><pre style='background:white;'><tt>Florida that makes beautiful laminated bridges.</tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>But if I were going to use the original, then yeah, I'd fire up the bandsaw.</tt></pre><pre style='background:white;'><tt>You should be able to saw it pretty smooth freehand. Or you could make some</tt></pre><pre style='background:white;'><tt>sort of post on your fence (like a several inch bump - maybe a vertical</tt></pre><pre style='background:white;'><tt>board of maple rounded on the end at a right angle to the fence) right at</tt></pre><pre style='background:white;'><tt>the blade - that way you would have a guide for constant thickness and yet</tt></pre><pre style='background:white;'><tt>it would allow you to change the orientation of the bridge as you go along</tt></pre><pre style='background:white;'><tt>the curve. You'd probably have to do the doglegs freehand though.</tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>Let me know if I can help you.</tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>Terry Farrell</tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>On Nov 1, 2012, at 2:18 PM, Ron Nossaman wrote:</tt></pre><pre style='background:white;'><tt>  </tt></pre><pre style='background:white;'><tt>> On 11/1/2012 12:40 PM, David Love wrote:</tt></pre><pre style='background:white;'><tt>>> I'm putting a new board in a MH piano (AA) and considering trimming </tt></pre><pre style='background:white;'><tt>>> that massive 40 mm wide bridge to something more reasonable like </tt></pre><pre style='background:white;'><tt>>> 33mm.  Has anyone ever done that?  What was your method other than </tt></pre><pre style='background:white;'><tt>>> careful band saw and a lot of sanding?</tt></pre><pre style='background:white;'><tt>> </tt></pre><pre style='background:white;'><tt>> Make a new one. You'll even get the chance to make a better length</tt></pre><pre style='background:white;'><tt>progression across the breaks.</tt></pre><pre style='background:white;'><tt>> Ron N</tt></pre><pre style='background:white;'><tt>> </tt></pre><pre style='background:white;'><tt>  </tt></pre></div></div></div></td> </tr> </tbody> </table> </div> </div> </div>