Cracking soundboards

[Openwood]

Hang on, why does a crack in a soundboard actually matter? Please don't shout at me, remember I'm not a technician!

Yesterday I played an old baby grand suffering from a few cracks about 5 inches long and I couldn't detect any adverse effect on the tone, in as much as it sounded exactly like every other knackered old baby grand I've ever played.

Is it a case of trouble stored up for later? Then again, given the state of the thing, I don't imagine there is a great deal of 'later' left - in which case I suppose you could argue the cracks haven't been anymore detrimental than anything else that's happened to it.

I can see why a scale model of the grand canyon suddenly opening up in your soundboard could be a problem but these looked like very small cracks that had been there for a considerable amount of time.

Just curious!

[PianoGuy]

Hang on, why does a crack in a soundboard actually matter?

They don't often cause a problem. They are a sign that the humidity levels are, or have been too low, but since sound travels along the grain rather than across it, if the crown is OK, there are no buzzes and the ribs aren't off at the back I wouldn't worry about 'em!

[Barrie Heaton]

Steinway have a bit about it on their site.

Compression ridges can be more of a problem than cracks on a sound board but cracks that follow on after compression ridges tend to buzz

Compression ridges are caused by pianos being placed in too damp an environment thus causing the timber to swell this swelling first crushes the fibres of the wood taking out some of the planks elasticity, then when the plank can go nowhere else the boards swell up in ridges the glue joints on the belly bars becomes weak.

Now if the piano is them placed in a dry environment the planks contract and because the fibres of the wood have been crushed even when the piano is in the 45% zone you will see small splits. In a very dry environment when the plank splits the fibres tear the as the movement is grater so the planks tend to come unglued from the bars.



Barrie,

[Aly]

When the tuner declared our piano dead she said it was because the soundboard was cracked. She said, and showed us, that she couldn't tighten the pins any more as they just un-tightened themselves again. There wasn't anything for them to grip. It was funny to watch at first, the pins moving her big tool back again. But it did mean we had to find a new piano.

[Openwood]

Thank you for the replies, I had always thought these cracks were the kiss of death so thanks for clearing that one up!

[Brumtuner]

"When the tuner declared our piano dead she said it was because the soundboard was cracked. She said, and showed us, that she couldn't tighten the pins any more as they just un-tightened themselves again."

More like the wrestplank was cracked.

"It was funny to watch at first, the pins moving her big tool back again"

The mind boggles.

[PianoGuy]

You filthy, filthy swine Brumtuner!

[tuna]

Indeed, a lady-boy piano tuner!
Can't be too many of those around....

[sussexpianos]

The best thing for cracks in a soundboard/ loose ribs when you don't want to shim (bit expensive as you need to de-string etc) is to use Wurth polyurethane glue. I use it a lot for gluing panels etc but it stops buzzing noises when faced with lots of cracks. Its like a resin but starts to expand slightly on contact with moisture. What you get is a very strong glue with great gap filling qualities. Afterwards you clean up the excess and varnish over. I have used it on many jobs with loose belly bars and it works like a wonder. I had a job the other day to investigate a buzzing noise. I counted 7 splits in the board and a loose bar. 20 min later I had filled the cracks, stopped the buzzing and had a coffee. The resin expands into the crack and then holds the wood together by bridging the gap. Its safe on all finishes ( we like it as it dosn't effect Frenchpolish) and if you then want to carry out a more expensive job laterof shimming, you can easily scrap out the glue or i use an airgrinder with a Spurlock bit which makes perfect V cuts.The main problem with cracks in the soundboard is whether its affecting the downbearing or the tuning stability. Only by shimming will these be sorted. Cracks in wrest planks is another thing which requires a new plank.On an upright, forget it, too expensive. On a grand, depends if its economicaly viable, but more realistic.

[Barrie Heaton]

Cracks in wrest planks is another thing which requires a new plank.On an upright, forget it, too expensive. On a grand, depends if its economicaly viable, but more realistic.

Have you seen the trade price from T&P Preston they give you a free Wplank if have have a full job and that's uprights as well


We had a guy form the US come over to stay with us he use to fill all the holes with resin redrill for size 00 and put 2/0 pins in with a bit of talk on the pins to stop them clicking. I tried it on part of an old vert worked well, pins were very good the piano was for the tip and that is were it ended.



Barrie,

[David B]

they give you a free Wplank if have have a full job and that's uprights as well

another mind boggling scenario ?

[Openwood]

another mind boggling scenario ?

Well at the very least it's fifty quid well spent

[sussexpianos]

Mr Openwood,
how do you know how much it costs??

[Openwood]

Mr. Sussex,

My rates are highly competitive

[sussexpianos]

so you have done market research into this matter then?