Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Matching hammers to belly, impedance, geometry

I've read a lot about the importance of matching replacement hammers to a piano's belly (soundboard) and action geometry.

Just how is the choice of hammers arrived at without resorting to guesswork and trial and error? Let's say that the piano in consideration is really old and therefore the soundboard and crown is not in the same state as when it was new. Therefore, just getting hammers that are like the original wouldn't work optimally.

So, how does one go about choosing the right set of new hammers?

Practice...and sometimes you still don't get it right.

Peter Grey Piano Doctor

Surely, there must be a better way, I hope.

The weight of the hammers should be the first thing you consider. Hammer weight has a profound effect on tone and touch. If you replace the hammers with heavier ones, the inertia of the hammer will rise, and the action will not play at all like it originally did.

In a grand:
Most of the time I get good results if the action is well regulated with a normal key and hammer travel and the key leads are normal like maybe 3 to 4 in the bass tapering to zero and maybe a couple keys with small leads on the back side of keys in the high treble, all friction regulated and normal touch weight like maybe 50 to 52 g down and maybe 30 or more g up, the hammers are close enough match.
Not to mention any machining of the hammers like tailing for checking or thinning/tapering.
If you go too light or too heavy the action regulation won’t be in a normal range.

I have read your posts a lot and understand you advocate light hammers. So, I have a Yamaha G7 of maybe 50 years vintage. So I go and order hammers. How do I choose between Gross 13, 14, 15, or 16?

So, how are we to know how light is too light and how heavy is too heavy, and what's just right? For the soundboard impedance, etc etc

Samples.

How many? Surely not a whole set? So this is trial and error? How many samples do you usually try before finding the correct ones? And how do you extrapolate the weight of a whole set and know what to order based on samples?

Also, as I've earlier theorized, the old soundboard wouldn't be the same state as the original. So if I choose hammers close to original weight, won't this be a mismatch?

I’d suggest an analysis of the existing piano before removing hammers or changing anything.
As for samples usually the first and last note in each section is good enough.
I would not put much emphasis on impedance.

The criteria I have used is whether it is a hammer that I feel I can work with, and whether it will fit into the piano and the budget I have to work with. Mass? I do not know what the original mass was, nor do I think that the manufacturer cared much. The mass is going to vary from note to note, and as long as it varies about as much as the original hammers did, well, new pianos vary a bit from sample to sample as well.

What matters is my ability to work with what I have to work with, and as I get better and better, there is less need to replace hammers.

May I suggest, as a rank amateur with no experience of changing hammers, that exchanging some hammers with lighter and heavier neighbours, not just next door neighbours, would help. Your record would show which weight is best for each note for the piano in its current condition. Then you could ask your hammer supplier for a best match.

Does it go without saying that the piano needs to be in a reasonable state of regulation first?

Sounds like a plan! Thank you!

A good quality hammer of the size and shape of the original plus a matching molding is what you need to know. As Ed says, excess weight increases inertia and removes pianissimo from the repertoire, screws up a glissando and fatigues the player. The hammer can be voiced to match the requirements but must first match the action.

When crown and bridges have minimally changed their position in relation to the strings then it's inevitable that the strikeline for the optimal position isn't what it was 50 years ago. Before getting new hammers you should slowly pull out the action mm by mm and listen to the sound of the hammers in different positions of their strikepoint as an absolute value of the position on the speaking length of the strings in the treble section.

A beautiful and perfect hammer that doesn't hit the sweet spot on the string is wasting quite some potential of the piano's capabilities in producing a beautiful sound.

A pianist strikes the string at region three-quarters of its length. A guitarist and violinist excites kick the string there too. Only gipsy cymbal strings sound right, I'm think. Make a piano construction where the hammer will cick the middle of the string and you won't need to creating the hammer shape or sounboard there.

I have asked the OPS question myself on forums and i have come to the conclusion that techs throw the impedance word around just to sound knowledgeable in science. But piano rebuilding is a craft, so that's the real mismatch.

Hammer selection is a preference most of the time. My process starts by asking the client what do they want. For instance many of my clients are piano technicians so they already prefer a certain hammer because they know the hammer and how to voice them.

When a customer leaves it up to me, I am very familiar with Ronsens, Ables, and Renner Blue Points.

A couple examples:
So i do a tap test first on the soundboard with the plate off.

I have an SD6 with a new light compression soundboard. Very Resonant and booming. I prefer to use Ronsen, but my client wants Renner Blue Points. Although i will voice them with Softener to increase sustain, and primarily leave the attack alone but correct for evenness.
Another piano I have is a Knabe 5' with a heavy Rib crowned board that doesn't resonate with a tap test but has nice crown. So i decided to go with Abel because it will add some sweetness to the attack.

Selecting size of the hammers:
Using the KISS method works 99% of the time. Weight the original hammers and aim for .5 to 1 gram less than the originals. Then I adjust the leads using the Fandrich weight bench system. I also do mock setups with an adjustable grand action to verify on unfamiliar brands, models, and especially on previously rebuilt pianos.

Hope that helps,
-chris

It does. Thank you

I’d agree with BDB’s perspective and also Chernobieff’s.

After years listening to and reading other technician’s perspectives I see that there are many perspectives. I don’t doubt the better ones get the results they want with their differing approaches, and that they’re going to have satisfied customers with these differing approaches if they do the work well (unless of course it’s completely off base).

The last piano I replaced the hammers on was a Steinway M. I used WNG Natural hammers which were heavier than the originals. Does it feel different? Yes. But the difference is better in my opinion, and in the owner’s opinion as well. Steven Jackson said above that heavier hammers will decrease pianissimo. However the pianissimo on this piano was improved tremendously (as was the tone)—for the first time since the owner bought the piano they feel like they can control pianissimo (I had previously regulated it with the old hammers trying to get whatever could be gotten out of them). The touch is a little on the heavy side but it’s nice to play.

The point is to not get too hung up on finding the ‘correct’ solution.