Piano scavenging adventures - ungluing the structure

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slowlearner
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Piano scavenging adventures - ungluing the structure

Post by slowlearner » Mon Oct 31, 2016 4:36 pm

Hey all,

In the last week or so, I've been pulling apart our family piano after it stopped holding tune. It's 135yo, so it's done it's time. The idea is use the timber for some instrument building projects. I've got as far as pulling the frame out.

Image

I'll soon be up to pulling the cabinet apart. It appears to be held together by hide glue. Idea on how to loose up the glue? I've got an electric heat gun? Would that do the trick?
Pete

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Re: Piano scavenging adventures - ungluing the structure

Post by kiwigeo » Mon Oct 31, 2016 4:57 pm

Heat gun on low setting should do the trick...
Martin

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Re: Piano scavenging adventures - ungluing the structure

Post by slowlearner » Mon Oct 31, 2016 8:51 pm

Cheers. :cl
Pete

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Re: Piano scavenging adventures - ungluing the structure

Post by lamanoditrento » Mon Oct 31, 2016 8:53 pm

I saw this great youtube vid about reversing hide glue joins

https://www.youtube.com/watch?v=5BiPbLjDT3I
Trent

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Re: Piano scavenging adventures - ungluing the structure

Post by slowlearner » Tue Nov 01, 2016 10:42 pm

^ That was great! Thanks for that link. :cl
Pete

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Re: Piano scavenging adventures - ungluing the structure

Post by slowlearner » Sat Nov 19, 2016 6:28 pm

Right, so this is as far as I've got with salvaging the soundboard. It's 135yo spruce... and probably was much old than that when felled in Europe some where. I won't horrify you with the butchery of how I got the bridges of off...

Image

My big problem now is, I don't want to hack all the braces off them lift the remains like I did with the bridges. The bracing is also 135yo spruce and would make awesome bracing stock.

Image

I've tried it with an iron... no cigar. And the heat gun is just too much. What I'm wondering about is steam, but I don't have a pressure cooker.
Pete

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Re: Piano scavenging adventures - ungluing the structure

Post by simso » Sat Nov 19, 2016 6:36 pm

Litle coffee machines are good for steamers as well

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Re: Piano scavenging adventures - ungluing the structure

Post by Kev3 » Sat Nov 19, 2016 7:27 pm

Dismantled a piano myself. A heated up palette knife and a water spray bottle lifted the braces. Mind you the hide glue was quite brittle on mine.
Gotta couple of crates of the keys and hammer mechanisms etc that I still haven't found a use for but was loathed to dump :D
...............
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Re: Piano scavenging adventures - ungluing the structure

Post by lauburu » Sun Nov 20, 2016 6:12 am

You could try one of those renovator multitools https://www.bunnings.co.nz/bosch-profes ... _p00276902
Use the long cutter and work your way under the brace while trying to avoid damaging the soundboard.
I pulled apart a wooden frame piano a few years ago. The most useful parts were four spruce columns about 100mm square. Wonderful bracing material.
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Re: Piano scavenging adventures - ungluing the structure

Post by blackalex1952 » Wed Nov 23, 2016 1:08 pm

I use radiant heat bathroom lamps mounted on a microphone stand along with a surface thermometer. I forget the temperature I use, but I basically work a warmed palette knife into the joint until it comes apart easily, then keep the temperature at that point. The heat is easily controlled by the distance the lamp is from the work. The heat lamps set up a heat gradient which, if not too steep, penetrates the timber to the glue line. Patience is the key, ie not pushing the heating process too fast. If I am removing a fingerboard or other parts where the surrounding parts of the instrument are vulnerable to heat damage, I use aluminium foil over wooden cauls as heat shields. It is important to watch the surface temperature where a finish is involved.
Slowly allowing the heat to penetrate is best, rather than a steeper heat gradient where the surface heats too rapidly. This method is better than steam or a heat gun. Steam expands wood fibres and requires de humidifying, heat guns don't penetrate the wood but heat the surface first. Using heat lamps leaves both hands free and is the most adjustable temperature wise. -Ross
"Everything I say on the topic is based solely upon inexperience and assumption!"

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Re: Piano scavenging adventures - ungluing the structure

Post by slowlearner » Thu Nov 24, 2016 5:27 pm

I've spent the last couple of days pulling the spruce braces off the soundboard. Man, what a mission!

I tried steam after buying a cheap pressure cooker ($23). No cigar. The wood just got really wet and the thin paint scraper I was using was just tearing it up. So back to the heat gun, scraper and 1" chisel.

Image

Basically what I'd do is heat the scraper up really hot, then slip it under the brace for far enough that I could put the chisel under the edge to lever it up. Then I'd heat scraper and the timber (as gently as possible) and work my way along until the brace came off. Only 2 braces splintered. The rest came off ok. Which is really cool, because the braces are also spruce and will make excellent bracing for acoustic instruments. Sorry there are no "how to" pics but I needed 3 hands as it was. Holding a phone was impossible.

Image

The soundboard was cracked in a few places. The longest, largest board has the biggest crack, but then I already knew that. I'm not all that stressed about it, because I can easily glue it up. The panels are 8mm thick, so I can easily thickness sand them down for other instruments. All of the spruce in the piano was hard, well seasoned and really strong.
Pete

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Re: Piano scavenging adventures - ungluing the structure

Post by blackalex1952 » Fri Nov 25, 2016 12:05 pm

This may be of interest if you haven't already seen it...
http://www.frets.com/FretsPages/Luthier ... etest.html
Cheers! -Ross
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Re: Piano scavenging adventures - ungluing the structure

Post by slowlearner » Fri Nov 25, 2016 8:36 pm

What he reports there is pretty much what I experienced. Even when the glue failed it took some timber with it, no matter how much heat I put in it. If that's the way HHG generally works, I'll stick to my titebond.
Pete

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