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BobbinBlueJay, you can upload images to the Piano World servers here. After you click Submit you'll get an error page: ignore that, and check your email for the link for your uploaded picture. Then use that link for an image in your post (go to Full Reply Screen, use the fourth button from the left on the posting toolbar, and choose non-floating image).
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Thanks PianoStudent88. Without those instructions, I don't think I'd ever figure that out. So here goes: Overview of the piano: Overview of the plate: Detail at the keyboard: Detail of two cracks at the high end (far right end: Detail of the crack on the left-middle strut: It was a nice looking restoration, but all for naught now, I guess. The restoration included a new pinblock as I recall. In that last tuning, he was driving some of the pins, I believe, but he did pull the key board, etc. and support the work with large clamps.
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Perhaps it's time to transfer "family history and sentiment" to a new piano. We already have a perfectly serviceable 1980(ish) Kawai. It was supposed to be temporary for the year that the Sohmer was being restored. Nothing special, but I guess it's the keeper now.
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I find those cracks to be most curious because they all show me anyway that there is a bending motion taking place with that plate given that they all are opening at the top, almost like the plate was lowered at the tail end maybe to compensate for some lack of downbearing, but then no shimming took place at the keyboard end of the pinblock so that any bending motion would be offset.Either that, or it was dropped and the capo bar was the point of impact. As far as repairing cast iron is concerned, I have had a couple of plates welded with no subsequent issues. The correct process is of course to heat up the plate and then it should be tig welded using high nickel welding rods. I am lucky to have found a fabulous welder here in Houston (American Heliarc) that is pure magic with a welder and scared of nothing. He will also happily tell me when things can't be fixed.
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There is or was a gap somewhere. The last one we saw was a new pinblock which turned out to be like 1mm thicker than the one removed and aparently it wasn't checked. Could have been anything, trash in the mating surface etc. Tig welding is the same way we do them, two different types of nickle rods though. Stiffer rod on the Filet weld and a slightly softer one at the showing surface so it can be smoothed out.
I realize Cast iron is the most ridgid material and cheaper but if they used cast steel they wouldn't ever have these issues. Blacksmith Anvils are made of Cast steel.
J. Christie Nashville Piano Rescue www.NashvillePianoRescue.comEast Nashville Bowling Green, KY Scottsville KY. Chamber of Commerce Member/Sponsor Putting inspiration in the hands of area musicians Through restoration/renovation
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From looking at the pictures I don't see excessive string bearing angle over the treble bridge which is what I would expect to see if the plate was forced to bend so much that it cracks. The bridge and board look original so the pin-block would have to be too thick for that to happen-and the angle of the string between bridge surface and speaking length do not look like the string plane is going uphill to the pin-block. Since there are two cracks in the treble most strut-I suspect the plate was dropped outside the piano most likely.
In a seemingly infinite universe-infinite human creativity is-seemingly possible. According to NASA, 93% of the earth like planets possible in the known universe have yet to be formed. Contact: toneman1@me.com
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old iron can be brittle, and that plate have zero flexibility, very tall and massive, but there must be some rocking motion from the pinblock, may be not well adjusted.
Professional of the profession. Foo Foo specialist I wish to add some kind and sensitive phrase but nothing comes to mind.!
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I have not noticed any age related brittleness in old plates. What mechanism would produce deterioration in grey iron under static load. They do not bend (plastically deform) over time in any detectable amount.
Steinways are typically bowed over the nose bolts by a little bit. Some plates will spring up 10mm at the tail.
In a seemingly infinite universe-infinite human creativity is-seemingly possible. According to NASA, 93% of the earth like planets possible in the known universe have yet to be formed. Contact: toneman1@me.com
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I have experience with gas welding and brazing particularly with tubular steel frames. I know enough from that experience to know how hard it would be to gas weld a cast iron frame like this. I've only tried my hand at TIG welding once, at least to get a feel for it. I can believe in the right hands maybe TIG welding could work. I'm also an architect with good background in structure. I had a great lecture in school about the history of iron and steel making. In the late 1800's you could read a building's structure by which parts were cast iron and which were wrought iron. I know that cast iron works in compression and can't take tension and therefore bending. These cracks come from bending somehow and the crack is on the tension side of the bend. Trusses are designed to have pinned joints at intersections of members so that every member stays in pure tension or compression, but a single casting like this will put the members in bending if the whole thing is racked. It's more like a Vierendeel truss. Yup, steel (and wrought iron) can take tension and therefore bending, so a steel plate might fair better.
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My understanding and experience with grey iron plates is that they will bend, (as in flex) but they will not deform, (bend permanently). They break when the flexing exceeds the strength. In essence they exhibit no plastic deformation from any load they carry. When the load is removed the casting returns to it original state.
A shock load distributed into the structure behaves somewhat chaotic in that the first impact point and any others that follow can magnify or cancel the distortion waves that move through the structure depending on timing and resultant combination vectors.
Grey iron has tremendous compressive strength but much less tensile strength.
In a seemingly infinite universe-infinite human creativity is-seemingly possible. According to NASA, 93% of the earth like planets possible in the known universe have yet to be formed. Contact: toneman1@me.com
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Ed there are different qualities of lamellar grey iron. The old one harden, due to phosphorous content in the often local mineral used.
That makes if memory serves a migration of carbon within the iron.
But I say that by memory, informations from iron molding association.
Also plate design of Steinway is poviding an "active" plate with thin braces , the sound of the plate is coloring the piano tone.
The plate pictured is passive type with massive braces in my opinion.
Bend way less , not intended too, those types of plates are not on dowels generally but on wood blocks , and the case can be more sonorous , the piano having a more soft and mellow tone then.
But I will have confirmation of those design points soon.
Professional of the profession. Foo Foo specialist I wish to add some kind and sensitive phrase but nothing comes to mind.!
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I have not noticed any age related brittleness in old plates. What mechanism would produce deterioration in grey iron under static load. They do not bend (plastically deform) over time in any detectable amount.
Steinways are typically bowed over the nose bolts by a little bit. Some plates will spring up 10mm at the tail. Actually, the automotive engine building companies used to dump engine blocks in a field for a couple of years to cure before machining them. Cast iron does "move" after it has cooled. It is to that factor that I attribute the springing up of plates (S&S & others). The assumption is that the installation was "stressless" but over time the plate or rim (or both) developed stress which is relieved when the plate is taken out.
Keith Akins, RPT Piano Technologist USA Distributor for Isaac Cadenza hammers and Profundo Bass Strings Supporting Piano Owners D-I-Y piano tuning and repair editor emeritus of Piano Technicians Journal
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A small bending up may relieve the strain from the tuning pins on the beginning of the braces , just a theory I heard, but not totally wrong.
How much should be the question...
I find about 34 mm at the tail of a recent Koncert 275 Boesendorfer. Not really impressing the factory guy I asked about .but their plate is not supposed to be torqued I believe.
Last edited by Olek; 04/22/13 02:32 PM.
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Keith, I have watched new Steinways having the plate installed and they bow them a little over the nose bolts. They call this part of "building tension into the piano".
Olek, what chemical change can occur in a casting that is warm and dry in a typical house? My understanding of grey iron in these circumstances is that it behaves like an inert substance. There is no way that I know of for ionic or covalent chemical bonds, nor the crystalline structure to change without great heat being added.
In a seemingly infinite universe-infinite human creativity is-seemingly possible. According to NASA, 93% of the earth like planets possible in the known universe have yet to be formed. Contact: toneman1@me.com
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Keith, I have watched new Steinways having the plate installed and they bow them a little over the nose bolts. They call this part of "building tension into the piano".
Olek, what chemical change can occur in a casting that is warm and dry in a typical house? My understanding of grey iron in these circumstances is that it behaves like an inert substance. There is no way that I know of for ionic or covalent chemical bonds, nor the crystalline structure to change without great heat being added. Good to know, Ed. I'm still learning. However, Steinway's practice doesn't necessarily invalidate the ongoing "curing" of cast iron, though. I've found plates warping up off nosebolts when unscrewed. If the only source of tension was cranking up the nosebolts, then they should be the highest point of support and the plate should remain in contact with them while floating above some point or points on the rim. Of course, another factor that could account for part (or most) of the phenomenon is the warping of the rim. Particularly being wood, stresses could develop which were in balance when the rim was first made but were released as the wood cures over the years. I'm sure you've experienced removing the plate from a piano when it appeared to have no tension in relation to the rim and then after repairing the soundboard the plate doesn't want to "lay down". Where does that come from? I have concluded it must be the rim -- which had been immobilized -- releasing stress, perhaps in combination with the drying process of preparing the board for shimming.
Keith Akins, RPT Piano Technologist USA Distributor for Isaac Cadenza hammers and Profundo Bass Strings Supporting Piano Owners D-I-Y piano tuning and repair editor emeritus of Piano Technicians Journal
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Ed I find that : A statistically significant increase in strength by aging at room temperature was observed in 23 of 25 independent studies in nine different foundries. This increase in resistance was 3.3% up to 13.5%. Curve as a function of aging time has a logarithmic form, the majority of aging occurring during the first ten days of storage. This increase in resistance is a function of time and temperature and can be accelerated by maintaining the specimens at temperatures between 85 ° C and 285 ° C prior to testing. The original doc is in French unfortunately http://cat.inist.fr/?aModele=afficheN&cpsidt=16806145It is also noticed as bore a hole in an old piano plate can show a more hard material than expected sometime. I was said it was a chemical process due to impurities in the cooked mix (phosphore). the same which is responsible for permanent deformation if one part of the plate is heated for welding (again that is not my specialty, I am just trying to have some global understanding)
Professional of the profession. Foo Foo specialist I wish to add some kind and sensitive phrase but nothing comes to mind.!
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Keith, I have watched new Steinways having the plate installed and they bow them a little over the nose bolts. They call this part of "building tension into the piano".
Olek, what chemical change can occur in a casting that is warm and dry in a typical house? My understanding of grey iron in these circumstances is that it behaves like an inert substance. There is no way that I know of for ionic or covalent chemical bonds, nor the crystalline structure to change without great heat being added. Good to know, Ed. I'm still learning. However, Steinway's practice doesn't necessarily invalidate the ongoing "curing" of cast iron, though. I've found plates warping up off nosebolts when unscrewed. If the only source of tension was cranking up the nosebolts, then they should be the highest point of support and the plate should remain in contact with them while floating above some point or points on the rim. Of course, another factor that could account for part (or most) of the phenomenon is the warping of the rim. Particularly being wood, stresses could develop which were in balance when the rim was first made but were released as the wood cures over the years. I'm sure you've experienced removing the plate from a piano when it appeared to have no tension in relation to the rim and then after repairing the soundboard the plate doesn't want to "lay down". Where does that come from? I have concluded it must be the rim -- which had been immobilized -- releasing stress, perhaps in combination with the drying process of preparing the board for shimming. I agree, releasing stress on an original piano must be done knowing that it may have been part of the sound of the piano. A dangerous situation, and one cannot avoid to think that the braces and rim have also moved under the stress and with age. But I believe that whatever acceptable tension within the piano case and plate, must be left if one want to find back the tone (I feel it have to do with the response time of the instrument) Piano rebuilders most often use a no or little stress solution when it comes to plate, I believe. A good understanding of the material used and the one of the plate design should help, while this subject is often left untreated, in my experience.
Professional of the profession. Foo Foo specialist I wish to add some kind and sensitive phrase but nothing comes to mind.!
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Another example that something is going on that cannot be attributed to any factory procedure is the wedge at the plate horn. How often does that just fall out after the string tension is released? Supposedly, it was driven in tight before the piano was strung up. Decades later, it just falls out -- or can be easily removed by hand before the plate is unscrewed from the rim.
Keith Akins, RPT Piano Technologist USA Distributor for Isaac Cadenza hammers and Profundo Bass Strings Supporting Piano Owners D-I-Y piano tuning and repair editor emeritus of Piano Technicians Journal
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Sell this handsome, but short, instrument to a decorator. Many pianos serve a purely ornamental purpose, and are only purchased so that the maid will have something else to dust. This will spare a working instrument. The owners would never find out whether it could be played or not, and if they did, they would be pleased to learn that it never needed to be tuned. And the daughters of the family would be pleased to learn that they could be excused from piano lessons.
If they should find that they want a piano that works, they might have the bucks and the risk-tolerant attitude to attempt the repair. Meanwhile, you are free to believe that this would happen.
Clef
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<Bump after a bit of a pause.> Sell this handsome, but short, instrument to a decorator. Many pianos serve a purely ornamental purpose, and are only purchased so that the maid will have something else to dust. ... Actually, talking to the tuner, he did say he once had to gut a piano for a stage production that wanted a prop that stage hands could get on and off stage between scenes, so I guess there is some need for prop pianos. He voiced a concern for possible further violent movement with a failed plate like this by just touching it, moving it or starting to dismantle it. Any thoughts on de-tensioning the strings? Backing off each string a little at a time in any particular order so as not to create a greater imbalance of forces and catastrophic failure? Though I'm not sure I'm up for the repair path, but it might be nice to know if there are any such talented TIG welders in this area (New York to Boston). You would think so given Connecticut is home to so many fabricators of jet engines, submarines, helicopters and firearms
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Piano
by Gino2 - 04/17/24 02:34 PM
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Piano
by Gino2 - 04/17/24 02:23 PM
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