So it's the 4' strings that are contacting the board? In that case, yes, I suppose you could put one under the 4' bridge. I have never run into that, but I don't see why it wouldn't happen. Probably due to the board being dried too much before installation, relative to its later environment. No need for hardwood as dowel material. It just supports the spring, and it is the spring tension that supports the bridge/board. You should know that the ribs on a harpsichord do not run under bridges. There are typically a set of ribs and a cut off bar to stiffen the area in the bass corner of the board closest to the player. The board is unsupported under the bridge. Additional support is offered by the 4' hitch pin rail, which is what holds the 4' hitch pins, and is mortised into the inner case rim. So the bridges ride on unsupported board, a few inches on either side. Which explains why there is usually at least a bit of a trough where the bridge is. Bridge rolling can be corrected to a degree by back pinning. I'll attach a photo. It's a simple procedure, drilling a hole at an appropriate angle below the string where it is originally, pounding in a pin (a center pin works), then pulling the string around it. Or you can capture the string when you first install the pin. Sometimes a bit of lowering of tension is helpful, but not usually necessary. I have not bothered lowering tension when installing a happiness bar, nor when back pinning. Fred On Sep 28, 2009, at 4:30 PM, G Cousins wrote: > Fred, > I'm guessing this should work on the 4' bridge as well. Yes? > Hardwood (dowel) not necessary. (??) Think hardwood would have any > affect? > Also, assuming lower tension prior to installation. > Gerry > > From: dmckech at ithaca.edu > To: caut at ptg.org > Date: Mon, 28 Sep 2009 16:54:51 -0400 > Subject: Re: [CAUT] soundboard possible OT for list > > Fred, > > In the version of this I heard a piece of cloth, felt or leather was > added to the top of the spring to prevent digging/indenting the > bottom of the soundboard. Thoughts? > > Don > > Donald McKechnie > Piano Technician > Ithaca College > dmckech at ithaca.edu > 607.274.3908 > > From: Fred Sturm <fssturm at unm.edu> > Date: September 28, 2009 4:41:40 PM EDT > To: caut at ptg.org > Subject: Re: [CAUT] soundboard possible OT for list > Reply-To: caut at ptg.org > > > On Sep 28, 2009, at 2:08 PM, G Cousins wrote: > > List, > I have an issue with a Harpsichord soundboard.(20 yrs old, not a > kit) 4' rank bridge is rolling due to board warping and waving. > Strings are now buzing from contact with board. I'm thinking perhaps > riblets or something around that line. > This is likely off of typical CAUT concerns or threads so if anyone > wants to discuss some ideas on this topic contact me off list for > more details. > Thanks, > Gerry Cousins, RPT > West Chester University of PA > cousins_gerry at msn.com > gcousins at wcupa.edu > > Typically the 8 foot bridge has gone down, and the hitchpin rail > has gone up. The cure I have used, maybe 3 or 4 times (always > successfully so far), is one I learned from Hubbard (though I > modified their instructions quite a bit), called at the time a > "happiness bar." It is one or two dowels (one in the middle, or > perhaps two at 1/3 distances) inserted from beneath, with a fairly > strong spring on top, a coil spring about the diameter of the dowel > or a little less. Drill a hole in the top of the dowel and insert a > smaller diameter dowel in the hole. The smaller dowel is about the > inside diameter of the spring, and holds it in place. The spring > will need to hit the soundboard directly under the 8 foot bridge. > The bottom of the dowel rests on the bottom of the case. > It's actually quite easy to do. Drill a hole (or two) in > appropriate places through the bottom (use a square to measure the > right distances in so that you will be under the bridge). The hole > should be a bit larger than the dowel, and large enough to insert a > finger or two comfortably. Measure the distance up to the bridge, > cut the dowel to be somewhat shorter. Have maybe three strengths of > spring available. Place the spring on the top of the dowel, held in > place as described above, insert in the hole. The spring should > contact the soundboard under the bridge, at which point you press > upward with one finger and manipulate the bottom of the spring so it > slides over and rests on the harpsichord bottom next to the hole. > And maybe decide that a different spring strength or length is > needed, so remove and adjust as needed. The hole needs to be large > enough that a finger can get in and pull the dowel back over to the > hole for removal. > I attach some photos from I class I taught that should help. > > > > Regards, Fred Sturm University of New Mexico fssturm at unm.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20090928/746a8a68/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: -30 back pin bridge.jpg Type: image/jpeg Size: 437580 bytes Desc: not available URL: <http://ptg.org/pipermail/caut.php/attachments/20090928/746a8a68/attachment-0001.jpg>
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