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Hey all, I'll be doing a video series on a complete restoration of an Upright piano every step of the way. 4 videos in the series already. Like and subscribe to follow along. Enjoy! Here's my latest vid. -Chris
There is now 13 videos in the series. It's becoming an in depth course on rebuilding. The latest video is How Much water is removed from a soundboard when reducing the moisture content to a low percent?
Your dedication to detail is so good to experience. Long ago I was an electrical engineer and worked on everything from 95 ton electric furnaces to CNC machine controls. I worked with my hands and brain but like you, tools were my friends. Watching you working and being generous with your skills and knowledge has been such a rewarding experience. If things had been different 60years ago I might have as easily worked as an apprentice piano technician and would have been happy to have been apprenticed to the likes of the man 'Where Tone is the Key'. Keep up the videos and see you on PW. Ian
I think you'd have needed to be in the USA for that to happen, Ian! In the UK 60 years ago your 'apprenticeship' might have been in the piano workshop of a large musical instrument retailer, 'modernising' 1880s uprights by putting curved legs on them and, literally, cutting corners!
I have a 1950s Fletcher & Newman catalogue, and it has pages of all those casework modernising things, including many styles of curved legs.
Hey! BDB was right! The Hamilton Piano Co. West Palm Beach did a little video. Tone wood transducer devise. "check it out" the phenomenon. Funny!!! Mr. Chernobieuf saw this video and did not mention that he saw it after I asked if any one saw this thing. It is very- very interesting, it is what happens when the crowning forces the ribs into a curve.
Especially in the treble. The SB is on the ribbing! they do the work!
After I bust out the old junk, i replace it with brand new Seasoned Tone Wood. The main reason for that is because of the cyclical nature of humidity. Imagine what the wood goes through: a hundred years, four seasons per year of expansion and contraction, I could only imagine what the irreversible damage to the cells are. Look how much water a soundboard can take on and remove The damage was occurring across the whole panel and every cell long before the crack became the manifestation of the damage. Its not isolated. So what do i do with the old stuff? I put it in my wood stove, I usually have enough to keep my shop warm for a week. Then I collect the ashes (minerals from the tree) and spread it on my garden. This way I remove the clay content eventually and grow more food. Yum. And just like the other parts of the piano, I wouldn't reuse the hammers nor the strings either for practically the same reason wear and tear. -chris
Last edited by Chernobieff Piano; 07/22/2108:47 PM.
Yes crushed cells are only in your imagination,,,there are no crushed cells in these old old SB's. That thinking is extremely misleading and incorrect! What happens over time is the exact opposite! "shrinkage"
Richard, you don't seem to be appreciating the word cycle - expansion and contraction. When the cells crush against each other damage occurs, then that damage is further increased with the expansion resulting in tearing. Cycle means over and over again. The fact that you are removing an old board with cracks shows the damage result of many cycles. You don't have to take my word for it, here are a couple micrographs so you can see for yourself.
I as Chris knows, call it compression set. One graphic demonstration is to gently hit the wood with a hammer and do it harder then harder until you get a dent that don’t return to its original shape. There is physics in it that corresponds to the physical characteristics of the wood species and the mass and velocity of the hammer and the cross sectional area of the wood it’s hitting if anyone wants to go there. Dramatic moisture content changes in the wood is a similar hammer.
Oh! Bet a dollar! that micro-graph is not from an old piano SB, say a hundred years old. "BET"
Baloney! I say,,, Sure damaged cells but until we can reference the origin of this photograph and see for ourselves what this is. Please. Bet another dollar it's kiln dried.
Yes when we re-crown we do have to deal with some compression set but not in the extreme most everyone thinks. So far we haven't found any crushed cells, but just a little misshapen and only on the bottom side. It is not a problem. Next re-crown is an 1857 Bluthner 8'something? we will check on the crushed cells and let you all know if we find any.
Richard, You won't. The fact that you were/are looking for crushed cells shows that you're still not grasping the concept. The crushing and weakening occurs during the compression stage and tearing during the expansion stage. The cracks are a visible manifestation. Once there are cracks and separation, how can there be crushed cells thereafter? The compression is gone. Its not just a matter of reusing old wood, but the wood has been under various unknown stresses with unknown internal damages and thus has an unknown shelf life. I would liken it to putting bald tires on a new car.
A very good and well thought out question!! I'm sure there are many opinions as to choice.
I've tried various glues over the years, but drifted to T3 because of its strength and workability. It's the strongest Titebond at 4,000 psi, and it flows better than 1 and 2 and has a slight longer work time. Perfect for solo work.
The nature of the joint (vertical Maple Lam to soft spruce) i don't think will be a problem in a 100 years to bust apart nor to clean the rim surface as when it fully hardens it is easy to sand and chisel. And perhaps in the future they will have a chemical solution. But that's the future, my main concern is the client at hand.
Always looking for a better glue of course. Acoustic transparency was mentioned in another thread by Foote and it is another parameter bearing in mind. Hot hide glue is the time proven almost perfect glue except for its workability which causes problems. Adding urea to lengthen its work time weakens it.
Last edited by Chernobieff Piano; 07/29/2109:31 AM.