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I asked several piano technicians if they can fix it. The one of technician said it can fixed very easily with CA glue and the false beat is uncommon in most pianos. The rest of piano technician said false beat can be mitigated but cannot be removed. The other technician said false beat is very usual in most of pianos and never cannot be removed and said CA glue is just temporary solution.

I was confused which technician was telling truth. By the way I don't trustnthe first tech as he couldn't solve the strange noise issue in past. After all, I solved it by myself by finding loose nuts inside of piano.

I am currently working on this issue myself. I know of three causes and all can be fixed, and one cause never gets mentioned.

1) Terminations are not clean. For example, the capo bar can be worn out with numerous grooves creating poor termination. And the bridge notching can be poor.

2) Loose bridge pins. Yes, CA glue has become a quick repair, but the real problem is the bridge cap.

3) Bridge cap material. This one is not ever discussed. Most caps are made out of hard rock maple. But I have come to the conclusion that todays HRM is not the same as what they used in the past. I have switched to a harder wood species with magnificent results. A simple rule is if you can leave a fingernail trail in the wood, it's too soft.
-chris

Seems to me that Ed McMorrow has pointed to the bridge cap in the past in this regard.

Peter Grey Piano Doctor

Currently my bridge caps are made from really hard boxwood, but since the material is now older than 130 years old, cracks have shown up and at least one crack produces an unclean sound that nobody has been able to fix, so I am looking at replacing the entire set of bridge caps. While I have found boxwood in sufficient quantity, that material is young and has not been dried properly, so it's unusable for the purpose.

What material other than maple is there that is readily available and dry enough to be usable for bridge caps?

Why don't you want to use Maple?

Whatever happened to the "stone tone" or whatever it was called granite bridges that were discussed a few years ago? I found this with a quick googling: http://www.slipperyrockgazette.net/index.cfm/pageId/631

Paul

Never mind, my technician has just found a source for dried boxwood that will cover both bridges in my Steinway and that's what we will use.

I don't want to use maple simply for the fact that boxwood is the original material. And since the acoustic assembly in itself is really beautiful, I'd like to keep it as close to its original state as possible, while doing the kind of rebuild steps that simply are necessary after 130 years i.e. strings, agraffes, capo bar evenness. We're even trying to keep the original pins, since they are firm in the pinblock and allow for nice tuning across the whole range.

What species is boxwood? I always thought it was rather soft.

Peter Grey Piano Doctor

The best bridge cap material in my experience is what friend makes for me.
Multiple layers of thin hard rock maple veneer glued with west system epoxy.
The laminate is superior to solid wood of any kind imho.
My Sauter upright has a laminated cap but it don’t look like maple.
No false beats.

https://en.wikipedia.org/wiki/Buxus_sempervirens

"Slow growth of box renders the wood ("boxwood") very hard (possibly the hardest in Europe) and heavy, and free of grain produced by growth rings"

I agree with Chris that the problem is in large measure due to the poor quality of the rock maple available to us these days no matter what the price. Anyone who has renotched the bridge on a hundred year old Steinway can tell you that wood was harder and denser than the rock maple available to us presently. The maple of 100 years ago came from large and mature trees where growth had slowed down and the resulting wood was tighter grained, denser, and harder. In contrast, modern trees are lucky to make it to 100 years before being harvested. So they are early and rapid growth from smaller trees, which means the lumber is softer and there is less lumber that is well quartered available for sawing. This wood is used by Steinway and other makers, and many of the pianos are rife with false beats. No doubt Chris has tried to find good well quartered Maple lumber for bridges, as have I. Too often we are disappointed.

Gene, I have made bridge caps from horizontal laminates of quartered maple veneer. I have used both West System Epoxy (in the way that Ron Nossaman used to) and Unibond 800. I went to the Unibond 800 because I decided that the epoxy did not do what Ron claimed it did - he was claiming that the epoxy saturated through the .6 mm. maple laminae, thereby hardening the maple beyond its natural hardness. All one has to do is look at the glue lines to know that is not true. It penetrates very little into the wood. And the wood veneers come from trees likely of even lesser quality than the quartered stuff we get for bridge stock. f there is a gain, it is not much. Making these caps is not hard, but it takes time that is not justified by the result.

I have been experimenting with alternative woods for bridge capping for several years. During that time I have become friends with a luthier wood supply with great knowledge of tonewoods, with about 200 different species in his barn. While I have been getting the best maple I have seen from him and he saws it dead on the quarter for me, it is merely very good compared to what else I can get. So I have taken advantage of his extensive knowledge to explore good substitutes.

The Janka hardness of rock maple is about 1450. I suspect that most of the maple we get does not approach that value. So I would be looking for woods of greater hardness than maple, ideally native woods. I am limiting myself to Janka hardness for this discussion, which is definitely oversimplifying things, as you need to attend to things like crushing strength, elastic modulus, modulus of rupture, and average dried weight. Also, porosity and tightness of grain. Put it all together and there are few woods that check all the boxes. Some woods that show promise are Black Locust (janka hardness of 1700), Persimmon (2300), Hop Hornbeam (1860), and American Hornbeam (1780). For tropical hardwoods, I have used both Greenheart (2530) and Pau Ferro (1960) in pianos. Pau Ferro seems to have all the good characteristics of maple, only better. Very tight and small pored grains. Drills and notches well, and does not chip. It is also an oily hardwood, so it must be glued carefully.

The issue that we have in the US for boxwood is a lack of availability. Also the trees are generally quite small, so suitable lumber is very hard to come by. Other than that, a very good wood.

Chris, I hope you will not consider your new substitute for maple a state secret and share the name of it, and what you like about it. That would enhance the discussion.

This G10 is a very nice material which I have in a couple of knife handles. Very easy to work with.

Gene, I have made bridge caps from horizontal laminates of quartered maple veneer. I have used both West System Epoxy (in the way that Ron Nossaman used to) and Unibond 800. I went to the Unibond 800 because I decided that the epoxy did not do what Ron claimed it did - he was claiming that the epoxy saturated through the .6 mm. maple laminae, thereby hardening the maple beyond its natural hardness. All one has to do is look at the glue lines to know that is not true. It penetrates very little into the wood. And the wood veneers come from trees likely of even lesser quality than the quartered stuff we get for bridge stock. f there is a gain, it is not much. Making these caps is not hard, but it takes time that is not justified by the result.“

West system with the proper adhesive fillers bonds the veneers very well. Never had any problems.
I thought that Ron used the plain unfilled epoxy just for coating and penetrating the top of the bridge cap - seems to leave a hard smooth surface that I prefer to dag.

Unless you starve the glue joint by too much clamping pressure, you don't need fillers to have a strong epoxy glue joint, one that is stronger than the wood itself.

Ron did use plain epoxy to coat the the bridge cap, and painted the notches and sides as well with it. His reasoning was that it could serve as a vapor barrier and the wood would move less with humidity changes. I have done the same. The coating would harden the top layer somewhat. Penetration would be minimal, no greater than anywhere else.
t

I chose Hickory. Its rated at about 1780, but the pieces i have are 1840. I go to the lumber mill and hand choose mine. I select the light color pieces. Hickory is perfect choice for me because it machines very nice and chisels very nice, is available everywhere, and its very inexpensive compared to other choices. When I switched from maple to hickory, the tone difference was huge, very clear. Much more clarity and sustain. When i was drilling bridge pin holes in maple, I could pull the pins back out with medium difficulty. With the same drill and pin size, drilling into hickory the pins could not be pulled back out.
It was never recommended for bridge caps, but i had to go with my gut and give it a try. Very glad I did.

-chris

I had considered Hickory, the Wood Database shows that it checks all the boxes. But it is not common to New England, so I focused elsewhere. There are a total of 13 different species of Hickory in North America. About half of those are on the softer pecan side. Which species are you using? From the Tonewood Data Source (a valuable online tonal resource if you have not seen it): " ...has tonal characteristics similar to Mahogany. tonally well-balanced and just a bit subtle in the mids, bright-toned, like a mahogany without so many overtones. " What is your sense of the tonal qualities of Hickory, by way of comparison to Maple? (my experience of Maple is that it is a bit thin and recessive in the mids when compared to some other tonewoods).

Are you able to get your Hickory quarter-sawn? Or can you get pieces large enough that you can re-saw it into quarter?

Another interesting tonewood that I left off my earlier list is Persimmon (2300). It is a member of the Ebony Family.

I have not used it yet, but I have enough black locust to cap a treble and bass bridge when I am ready. It has one of the fastest velocities of sound of all the tonewoods. It rings a long time in the tap test, and is credited with a long sustain. (i use a mid treble hammer on a shank to do my taps as opposed to the tip of my fingers. My friend Tom the luthier wood supplier likes this way of testing).

You've hit upon the lumber trades refusal to tag each tree's true genus. Only way to know is if you cut the tree down yourself. So hand selecting becomes important. I cut the pieces into 1/2" x 3/4" pieces and glue then into small panels so that i am in control of drying and bridge angle. Even the pecan when i have seen it identified was much harder than the maple. Harder woods are hard to get and expensive because the wood itself burns up chains and is hard to harvest. Plus gluing becomes more technical. After working with the hickory, i'm completely happy with it.

Fringe benefit = waste wood makes for great BBQ smoking!
What's the density of mesquite?

[sorry for the OT, I couldn't help it ;)]

I have read that they just throw it into the pile without much in the way of distinction. Tropical hardwoods can have many names that suggest something they are not, and more than one species can have the same "name". You really need the scientific name to know exactly what you are buying, as you indicate. Does the fact that you are working with such small pieces in the manner that you are mean that much of the stock is coming from smaller trees? (Which is a reality for a lot of available stock of certain kinds of woods).

Again my question, what tonal differences do you notice between Hickory and Maple?

these harder woods ask for deadly sharp tools that are kept that way.

the Average Dried Weight of Honey Misquite from the American Southwest is 51 lbs.