Hammer Hardness Measurement

Posted by: Grotriman

Hammer Hardness Measurement - 05/08/04 11:18 AM

Well I used my durometer. It's scale says "Shore A-2" not just "Shore A". I am not yet sure of the difference.

In the base the hammer felt on the side (equator?)is 85, the felt near the striking point is 90. In the treble it is 80 and 85 at the tip.

I will report back on my buddies' 1935 M&H.

My tech says the old Steinways had brilliant tone yet the hammers were spongy when you squeezed them. This is certainly different from the Grotrian Abel's where they are really hard!

Anybody else have any hammer information?
Posted by: lb

Re: Hammer Hardness Measurement - 05/08/04 11:33 AM

G
Ironic, but I checked a set of Abels just today.

This was a raw unmounted set and there were 94 hammers in the set and I just checked the strike point.

They ran a consistant increase from 84.3 on #1 to 98.0 on #94. There was one that was wild, #30 was 88.0, #40 was 90.6 but #35 was 83.9, other than this one immaculately consistant.

lb
Posted by: Grotriman

Re: Hammer Hardness Measurement - 05/08/04 01:21 PM

lb,

Please regard your measurements as much more accurate than mine as my action was lying in my lap and I was struggling to balance everything and take the measurement.
Posted by: lb

Re: Hammer Hardness Measurement - 05/08/04 01:35 PM

G

You have to stroke with whatever tools you can.

This piano company lets me come in and piddle around in their R&D dept on Saturday mornings when I am in town.

I was curious about the consistancy of their hammer supply and pulled one set out of a batch and tested it. Their equipment is a little better than mine in my shop.

lb
Posted by: Del

Re: Hammer Hardness Measurement - 05/08/04 01:59 PM

 Quote:
Originally posted by lb:
G
Ironic, but I checked a set of Abels just today.

This was a raw unmounted set and there were 94 hammers in the set and I just checked the strike point.

They ran a consistant increase from 84.3 on #1 to 98.0 on #94. There was one that was wild, #30 was 88.0, #40 was 90.6 but #35 was 83.9, other than this one, immaculately consistant.

lb [/b]
Unfortunately these numbers tell us very little about the tonal performance of the hammer.

During my hammermaking experiments a few years back we tried to come up with a way to measure Shore hardness that would help us predict the tone quality and harmonic spectrum we could expect from a given set of hammers. But to no avail. The problem is that a Shore Durometer measures only surface hardness whereas the tonal characteristic of the hammer depends on a complex mix of characteristics that are most closely related to an elusive mass/resilience ratio. The closest we came to was with a modified Resiliometer. The hammer would be thrown at a taut string with a given velocity and we then attempted to measure the return, or rebound, velocity. The difference figure gave us what we called a ‘rebound factor.’ Unfortunately the project was terminated before we learned much of any real value from it. Well, we learned a lot but the elusive tone predictor remained elusive.

Del
Posted by: Alex Hernandez

Re: Hammer Hardness Measurement - 05/08/04 02:04 PM

 Quote:
Originally posted by Del:
 Quote:
Originally posted by lb:
[/b]
Unfortunately these numbers tell us very little about the tonal performance of the hammer.

During my hammermaking experiments a few years back we tried to come up with a way to measure Shore hardness that would help us predict the tone quality and harmonic spectrum we could expect from a given set of hammers. But to no avail. The problem is that a Shore Durometer measures only surface hardness whereas the tonal characteristic of the hammer depends on a complex mix of characteristics that are most closely related to an elusive mass/resilience ratio. The closest we came to was with a modified Resiliometer. The hammer would be thrown at a taut string with a given velocity and we then attempted to measure the return, or rebound, velocity. The difference figure gave us what we called a ‘rebound factor.’ Unfortunately the project was terminated before we learned much of any real value from it. Well, we learned a lot but the elusive tone predictor remained elusive.

Del [/b]
Del,

Wouldn't the amount of bearing, combined with the belly assemblies ability to distribute and maintain energy also play a critical role in the character of its sound?

I feel that the hammer plays an important but finite role in the tonal character of the instrument. Am I barking up the wrong tree?
Posted by: Del

Re: Hammer Hardness Measurement - 05/08/04 02:09 PM

 Quote:
Originally posted by Alex Hernández:
Del,

Wouldn't the aount of bearing, combined with the belly assemblies ability to distribute and maintain energy also play a critical role in the character of sound?

I feel that the hammer plays an important but finite role in the tonal character of the instrument. Am I barking up the wrong tree? [/b]
Yes, of course. But the object of tests like these are to isolate the effect of just one component. In this case the hammer. It does little good to attempt any real understand the whole if we cannot understand the performance of the individual components.

Del
Posted by: lb

Re: Hammer Hardness Measurement - 05/08/04 02:11 PM

Well the almighty one has addressed me. I am in awe.

Del,I thought you said at one point that you wouldn't dignify my existence by addressing me, or words to that effect.

lb
Posted by: Alex Hernandez

Re: Hammer Hardness Measurement - 05/08/04 02:22 PM

 Quote:
Originally posted by Del:
 Quote:
Originally posted by Alex Hernández:
Del,

Wouldn't the amount of bearing, combined with the belly assemblies ability to distribute and maintain energy also play a critical role in the character of sound?

I feel that the hammer plays an important but finite role in the tonal character of the instrument. Am I barking up the wrong tree? [/b]
Yes, of course. But the object of tests like these are to isolate the effect of just one component. In this case the hammer. It does little good to attempt any real understand the whole if we cannot understand the performance of the individual components.

Del [/b]
Well that makes perfect sense. But why would one assume that a complete sense of tonal performance be achieved by isolating this component from the the other components that contribute to its overall character?

In the end doesn't the hammer introduce energy and establish the excursion of the string? It's elasticity and density determine how it does this. The rest of the story is written by the bridge/board/rim relationship.

I suppose the point I was making was that the harmonic spectrum of the hammer is also a reflection of these related components, is it not?
Posted by: Rick Clark

Re: Hammer Hardness Measurement - 05/08/04 03:17 PM

Women laugh at you guys, you know.

;-)

Rick Clark
Posted by: lb

Re: Hammer Hardness Measurement - 05/08/04 03:37 PM

Rick

Anything for a laugh, but are you sure just women?

Damn, I was just conducting a simple QC test to check the consistency of a supplier to the manufacturers specifications. I wasn't trying to part the Red Sea in the evolution of the piano.

lb
Posted by: Grotriman

Re: Hammer Hardness Measurement - 05/08/04 03:44 PM

 Quote:
Originally posted by Alex Hernández:
 Quote:
Originally posted by Del:
 Quote:
Originally posted by Alex Hernández:
Del,

Wouldn't the amount of bearing, combined with the belly assemblies ability to distribute and maintain energy also play a critical role in the character of sound?

I feel that the hammer plays an important but finite role in the tonal character of the instrument. Am I barking up the wrong tree? [/b]
Yes, of course. But the object of tests like these are to isolate the effect of just one component. In this case the hammer. It does little good to attempt any real understand the whole if we cannot understand the performance of the individual components.

Del [/b]
Well that makes perfect sense. But why would one assume that a complete sense of tonal performance be achieved by isolating this component from the the other components that contribute to its overall character?

In the end doesn't the hammer introduce energy and establish the excursion of the string? It's elasticity and density determine how it does this. The rest of the story is written by the bridge/board/rim relationship.

I suppose the point I was making was that the harmonic spectrum of the hammer is also a reflection of these related components, is it not? [/b]
Alex,

In any multivariable system where one is trying to improve the overall result, you hold all variables constant save one and try to determine the improvement by varying that one. Then move to the next variable.

Is that what you are asking?

Of course where the variables interact, this approach may or may not work based on the level of interaction.
Posted by: Del

Re: Hammer Hardness Measurement - 05/08/04 03:44 PM

 Quote:
Originally posted by lb:
Well the almighty one has addressed me. I am in awe.

Del,I thought you said at one point that you wouldn't dignify my existence by addressing me, or words to that effect.

lb [/b]
No, I don't think so.

If memory serves you were making a real issue of certain manufacturers and/or distributors hiding behind names that have nothing to do with who it is actually building them.

I was simply trying to make the point that piano makers are not the only ones hiding behind misleading or meaningless names.

I think it is nice to know who one is dealing with whether that happens to be a pianomaker or someone on the internet. I think a lot of nastiness would be avoided if folks were required to sign their real names to the stuff they write.

Sorry if this offends you.

Del
Posted by: Grotriman

Re: Hammer Hardness Measurement - 05/08/04 03:45 PM

Del,

The reason I posted the hardness was that someone in another thread asked for the numbers.

BTW are these numbers (85-90) typical in other hammers? Or are they unique to Abels?
Posted by: BDB

Re: Hammer Hardness Measurement - 05/08/04 03:53 PM

The hammer provides the all-important initial conditions of the excitation of the string. If not for that, everything would sound pretty much the same, if I remember my old differential equations class correctly.

If the hammer doesn't stay on the string long enough, if it is so hard that it bounces off the string before imparting its energy to the string, the sound will be thin, without much fundamental. If it is too soft, it damps more of the partials than is desirable.

One of the problems that we have understanding how strings works is that most people visualize them wrong. Even physics books will print these pictures of a string moving as the fundamental being this single arc in the string between the two endpoints, with the first overtone being an upward arc on one half of the string and a downward arc on the other half, and adding more up and down arcs for each overtone. The overall picture then looks like a number of little arcs superimposed on larger arcs.

Well, it ain't necessarily so. It turns out that when you actually add each of these overtones together, you actually get something that looks like the original fundamental, except that the high point of the arc is not in the center. Instead, it starts at the point of excitation (or where the hammer hits it), and moves to one of the endpoints of the string, flips over to the opposite side, and goes back the other way. Stretch a slinky or other big spring across a room, and you can see this.

The hammer provides the initial shape of that irregular arc. The qualities of the hammer determine the tone quality of the note.
Posted by: pete

Re: Hammer Hardness Measurement - 05/08/04 04:01 PM

Fascinating stuff.
Posted by: Del

Re: Hammer Hardness Measurement - 05/08/04 04:02 PM

[/qb][/QUOTE]Well that makes perfect sense. But why would one assume that a complete sense of tonal performance be achieved by isolating this component from the the other components that contribute to its overall character?

In the end doesn't the hammer introduce energy and establish the excursion of the string? It's elasticity and density determine how it does this. The rest of the story is written by the bridge/board/rim relationship.

I suppose the point I was making was that the harmonic spectrum of the hammer is also a reflection of these related components, is it not? [/QB][/QUOTE]


Again, yes, of course. But it is still necessary to understand, or at least try to understand, the characteristics of each individual part of the system. The failure to work toward this understanding has resulted in many pianos produced and shipped with mis-matched hammers.

If you have no idea what characteristics go into making a hammer with characteristics suitable for your particular overall scale how could you possibly decide which hammer to use? With any given scale some hammers will be too soft and/or light while others will be too hard and/or massive. It is useful to know and understand what is ‘hard’ and what is ‘soft.’ Until you know something about hammers how hammers work and how to predict their performance through testing and measuring how will you know where to start? Yamahas and Steinways require hammers of quite a different sort. Don't you think it will be advantageous for each manufacturer to understand how to measure and test for the physical characteristics of the hammers they specify and/or build?

Without some method of measuring and testing how will you be able to carry out even the most basic quality control? You can't just say, "Oh, well, it's all an interactive system and it will all work out in the end." Of course it is an interactive system but each component must function within certain design parameters and standards to form a unified whole.

Del
Posted by: lb

Re: Hammer Hardness Measurement - 05/08/04 08:18 PM

Delwin you said;
“If memory serves you were making a real issue of certain manufacturers and/or distributors hiding behind names that have nothing to do with who it is actually building them.”

Your memory is not any better than your perception was of the situation at that time. If you would have taken the time to read the whole thread that this occurred in you would see that it wasn't I taking issue. Oh, but it had nothing to do with taking the time to read it, it was a matter of perception.

You said;
“Unfortunately these numbers tell us very little about the tonal performance of the hammer.”

Again your perception of the situation was skewed, I was performing a simple QC test to determine the constancy of a supplier to a manufacturers specifications. Tonal performance was not a concern at that time.

You said;
“I think it is nice to know who one is dealing with whether that happens to be a pianomaker or someone on the internet.”

Look at my member number, I have been here from day one, and 2 years on the forum that preceded this one, a long time before you. I communicate daily with selected members here by, email, mail, and phone. I have been to some members homes and some have been to mine. I have not ever tried to sell or promote any product here.

It is nice to know who one is dealing with, but if you don't like it, don't deal. You addressed me remember.

You had a lot going for you, if you wouldn't have had that perception problem, you might have amounted to something besides a worn out technician writing pseudo scientific articles for the PTG journal

Keep Smiling
lb
Posted by: Del

Re: Hammer Hardness Measurement - 05/08/04 09:09 PM

 Quote:
Originally posted by lb:

You had a lot going for you, if you wouldn't have had that perception problem, you might have amounted to something besides a worn out technician writing pseudo scientific articles for the PTG journal

Keep Smiling
lb [/b]
I will.

Del
Posted by: byebye

Re: Hammer Hardness Measurement - 05/08/04 10:24 PM

Any opinions on this?

http://www.cs.ioc.ee/~stulov/smac03.pdf
Posted by: BDB

Re: Hammer Hardness Measurement - 05/09/04 01:57 AM

There's another analysis here:
Five Lectures on the Acoustics of the Piano.
Posted by: pete

Re: Hammer Hardness Measurement - 05/09/04 08:50 AM

Thak you BDB for that excellent and informative link.
Posted by: Bob

Re: Hammer Hardness Measurement - 05/09/04 09:42 AM

You can learn a lot by poking hammers with one voicing needle, determining which areas are harder than others and comparing it to the tone. Do this on different pianos, and get a better understanding of the piano hammer. Some things are just better done by hand.
Posted by: piqué

Re: Hammer Hardness Measurement - 05/09/04 05:57 PM

del,
please pay no attention to the behind the curtain. you are a very highly valued member of this forum, and you deserve all of our respect and thanks.

i am personally very grateful for the piano education you have given all of us, and hope you realize that you are held in the highest esteem here, and your presence adds tremendous value to this site.
Posted by: Steve Ramirez

Re: Hammer Hardness Measurement - 05/09/04 06:39 PM

Del, I didn't want to comment in this thread lest I give undeserved attention to your detractor.

However, I must say that I read all of your comments here and in other forums with great interest even when they pertain to things I find trivial or incomprehensible. Must be your writing style.

Thank you for contributing so generously.
Posted by: Grotriman

Re: Hammer Hardness Measurement - 05/09/04 10:35 PM

 Quote:
Originally posted by BDB:
There's another analysis here:
Five Lectures on the Acoustics of the Piano. [/b]
BDB,

Excellent! Thank you. Alot of info on hammer hardness. Also much else to look at. Thank you.

I also found MarkS's link as well when researching Estonia pianos... Very interesting as well, but will require my undivided attn when I can give it.
Posted by: Manitou

Re: Hammer Hardness Measurement - 05/10/04 09:19 AM

How quickly sides are picked and demarcation lines sketched in this forum.

I personally find worth in both members and would rather they both keep posting information, including occasional backyard rumbles, than try to pick my favourite and blast the other "detractor".
Posted by: Del

Re: Hammer Hardness Measurement - 05/10/04 10:19 AM

 Quote:
Originally posted by Grotriman:
Del,

The reason I posted the hardness was that someone in another thread asked for the numbers.

BTW are these numbers (85-90) typical in other hammers? Or are they unique to Abels? [/b]
My measuring of this type was done during the mid- to late- '80s and much may have changed among hammer makers since then. But, yes, the numbers you are getting are typical of many hammers. Most of them measured in the high 70s to mid 80s. The problem was that we couldn't come up with any consistent way to determine how hammers with some given Shore hardness readings were going actually sound once they ended up on a piano.

Del
Posted by: Del

Re: Hammer Hardness Measurement - 05/10/04 10:32 AM

 Quote:
Originally posted by MarkS:
Any opinions on this?

http://www.cs.ioc.ee/~stulov/smac03.pdf [/b]
This is the idea. This actually begins to define how the hammer works dynamically. It is a considerable extension beyond what we started to do. It gives an idea of how a specific hammer will actually work when it impacts a set of strings. Simply measuring surface hardness does not do that.

These folks, by the way, (in conjunction with Estonia) are doing some interesting work. While I take exception to some of their conclusions and application their basic investigations are coming up with some good basic information.
Posted by: Del

Re: Hammer Hardness Measurement - 05/10/04 10:39 AM

 Quote:
Originally posted by Bob:
You can learn a lot by poking hammers with one voicing needle, determining which areas are harder than others and comparing it to the tone. Do this on different pianos, and get a better understanding of the piano hammer. Some things are just better done by hand. [/b]
Funny you should mention that. This was another technique we tried. Inserting a needle into the hammer at various points while measuring and plotting the force required to press it home. While this was somewhat more reliable than measuring the surface hardness it was still not completely reliable. While I and another individual (who also had some considerable voicing experience) could ‘feel’ the difference it proved to be hard to quantify with numbers. It was also destructive — that is, testing altered the character of the hammer — and we were looking for a completely non-destructive technique.

Del
Posted by: Rick Clark

Re: Hammer Hardness Measurement - 05/10/04 11:06 AM

Since there doesn't seem to be any women looking at the moment, I guess I can throw in my own bit of geek knowledge here...

I think humidity needs to be factored in these hardness measurements. Although there seems to be a common notion that hammers in higher humidity are more "soggy" sounding, I find the situation in fact the opposite, at least in the case of modern hammers with significant tension in them. I find them brighter and believe they are harder. I believe I have also observed a correlation with the tendency of them to break strings.

Wool is hygroscopic and I believe there is a swelling that results from high humidity, making the tension higher. Wool is a kind of hair, of course, and look what happens to the hair on your head when you go from a place of low humidity to one of high humidity. For many of us, we find we have a new, unexpected hairstyle.

Regards,

Rick Clark
Posted by: piqué

Re: Hammer Hardness Measurement - 05/10/04 12:26 PM

hi, rick (woman lurking here, but not sure where the offense lies ).

i had wondered about the role of humidity myself. and the hair analogy is a good one (speaking as one who has naturally curly hair).

when humidity is around 53 percent, my piano sounds its best. in lower humidity, say around 42, i didn't like it as well. derick i think has also posted that his piano (the falcone) had longer sustain at lower humidity.

of course, since my treble hammers were replaced, i'm not noticing an "improvement" at higher humidity any more. but the tonal qualities do still change with even slight shifts in humidity. i find higher humidity confers a warmer richer sound. and lower humidity seems to have a tone with slightly less dimension to it.

i'm only experiencing this within a ten percent range, mind you.
Posted by: Rick Clark

Re: Hammer Hardness Measurement - 05/10/04 02:07 PM

Hi Pique,

My comment relates to a comment I made earlier in the thread.

Humidity also affects the way sound propagates through the air. So when there is a tonal change along with humidity change, one would guess that part of it is due to the change in hammer felt tension (for the tensioned *type* of hammer anyway) but also part of it is due to differences in the air itself.

However, I'm getting altogether too geeky here and must end it now.

Better to listen to music than listen to acoustics.

Regards,

Rick Clark
Posted by: piqué

Re: Hammer Hardness Measurement - 05/10/04 02:34 PM

 Quote:
Better to listen to music than listen to acoustics.
that would make a great tag line.

thanks for the insights, rick. hadn't thought about the density of the air itself being a factor.
Posted by: Grotriman

Re: Hammer Hardness Measurement - 05/10/04 06:14 PM

 Quote:
Originally posted by piqué:
 Quote:
Better to listen to music than listen to acoustics.
that would make a great tag line.

thanks for the insights, rick. hadn't thought about the density of the air itself being a factor. [/b]
Believe it or not, air is less viscous when it is humid. This has to do with the fact that the oxygen molecules are polar and have "magnetic" interaction with each other. When it is humid, the water molecules interfere with this attraction between oxygen molecules. In my experience, high frequencies are heard better in humid environments.