<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Michael G's mod A</title></head><body> <div>Michael and all,</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1">This close-up shows a metal shim which fell out of a place between the "dam" and the underside "nose" of the plate on my S&S 'A' . I stood it on the soundboard near its normal location. I can only hazzard its use as being intended to convey the pressure of the fully strung piano from the web to the dam and sound board. Any other ideas? It is about 1/4" thick.</font></blockquote> <div><br></div> <div>Take a look at the plate strut shown in your image, and note its vertical position relative to the string-plane of the strings. The string plane will run between 35 - 50 mm below the centreline of the plate strut. Clearly, the total string tension ( which will be between 16 - 18 ton for an A) will be trying to bend the struts down at the strut ends and up in the middle. Steinway have chosen to use quite small struts in this design, and this bowing of the struts will be tend to be worse with their instruments than say a Bösendorfer, which has much deeper and heavier struts (Bösendorfer don't use a horn system). The horn - wedge - tension collector system allows the back beams and case structure to take some of the load on the opposite side of the string plane, relative to that of the struts. This will help to prevent the bowing of the struts, stiffen up the whole assembly, and hopefully, result in better tuning stability and sustaining tonal qualities. A Steinway plate might still survive the string tension if the horn wedge was left out, but I'd be a bit nervous about its long term prospects, if it managed to get to pitch without collapsing.</div> <div><br></div> <blockquote type="cite" cite><font face="Arial" size="-1"> You can see the gap into which it fits. It was nor glued in place - should it be?</font></blockquote> <div><br> No<br> </div> <blockquote type="cite" cite><font face="Arial" size="-1"> I doubt it as the glue would give a deadness and tend to be elastic in situ. </font></blockquote> <blockquote type="cite" cite><font face="Arial" size="-1">Now all the strings are off, the soundboard gives a healthy bass "thwummm" of G# 0 @ A=431 when tapped with a fingers on the bass bridge. Having vacuumed off all the debris of ninety years I am about to gently wash the plate and soundboard with a damp cloth from a bowl of water with washing up liquid in.<img src="cid:a06110408bf12de06f1c7@[192.168.1.100].1.0"></font></blockquote > <div><font face="Arial" size="-1"><br></font></div> <div>Now that you've got it unstrung, I presume that you will be lifting the plate to see what's happening with the board.</div> <div><br></div> <div>A couple of compression ridges are visible in your image, to the right of the horn wedge.</div> <div><br></div> <div>Have a look at the following graphic I've drawn for you.</div> <div><br></div> <div align="center"><img src="cid:a06110408bf12de06f1c7@[192.168.1.100].1.1"></div> <div><br></div> <div>For a piano as old the one you're dealing with, there will be no way that the crown remains in a healthy condition. I know that some believe this is possible, but if you make up a plywood straight edge, with a cutout for bridge clearance, you will see immediately what I am referring to.</div> <div><br></div> <div>Almost all 90 year old boards will have collapsed to conform to the image graphic above. There will usually be some residual crown either side of the bridge, with a 'valley of collapse' running right along the line of the long bridge. You can usually place a straight edge under the bridge, on the under side of the board, and it will rock, showing that the crown has turned inside-out under the bridge. You can also try this on new pianos on the showroom floor, only to find that there is often an early onset of the syndrome.</div> <div><br></div> <div>Older boards in the second top string section will usually collapse as per the lower image in the graphic shown above. Again, using a plywood straight-edge, this is easy to see. Now they'll be some who'll swear and declare that their 100 year old 'wonder piano' still sounds as good as the day it was made even though the sound board might have sunken a bit. Well, I doubt that this is possible. While older instruments may still sound somewhat like a piano, they will in almost all cases sound significantly inferior to what they once were.</div> <div><br></div> <div>Well there you go Michael. There's a little project for you. Knock up a plywood straight edge during the week, and pull the plate next Sunday.</div> <div><br></div> <div>We've currently got a little project of our own going on at the workshop, doing a 'mouth-to-mouth job' on a collapsed sound board for a retired client. The patient in question is a Howard grand, which by the look of it was made by Challen of London. It was a bit short and 'honky' before we de-strung it, so I was already suspicious of the board. It turned out to be dead flat with a few small checks, which got significantly worse once we jacked it to what we judged to be an appropriate crown (I was a bit concerned that we might push the board of the rim altogether, but it held despite the creaking and groaning). While the crown is jacked we're giving it a heavy coating of epoxy on each side to produce of sort of epoxy/floppy-spruce sandwich (you never know, it might sound like a Hamburg D after all that epoxy - though I'll try to keep my expectations somewhat tempered). We'll set it up with just a small amount of positive bearing to see what sort of 'twilight performance' we can get out of it (there was no bearing anywhere at the time of pull-down). I gave David Love a call about the epoxy treatment, since I hadn't done it for over twenty years, and I remembered him talking about the procedure on-list some time back. As usual, David is a wealth of knowledge and was very helpful. We're also gluing a new set of bridge pins into the 'sad' bridges with West System epoxy.</div> <div><br></div> <div>Here's a few images of the process under way, with two showing the jacking operation.</div> <div><br></div> <div>Note that this piano has a sensible cut-off arrangement, whereby the inner rim and cut-off is bent as one piece. Very nice. The sound board is grossly under-engineered, but its going to have to stay that way. Both the piano and its owner are in retirement. This work might allow to piano to be reasonable company until she, ie. the owner, leaves this mortal coil.</div> <div><br></div> <div align="center"><img src="cid:a06110408bf12de06f1c7@[192.168.1.100].1.2"></div> <div><br></div> <div align="center">The 'jack' ends are made from free machining 5/8" hexagonal stock which is tapped with a 3/8" internal thread. Threaded rod (which is cheap to buy) can be cut to the desired length for jacking any piano. Two 5/8" or 16 mm spanners can be used for adjusting the jacks</div> <div align="center"><br></div> <div align="center"><img src="cid:a06110408bf12de06f1c7@[192.168.1.100].1.3"></div> <div align="center"><br></div> <div>Now I must get to work. I got up at 5 am to leave home around 6.30, and its 7.45 already. Aaaaah - the distractions of life. Now Michael - about that board?</div> <div><br></div> <div>Ron O.</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>