Brass alloy

[turf3]

Well, I'll readily admit I don't know about copper alloys that might have been in common use in the 1930s. That's well before the UNS which appears to have been instituted 1974. Of course there were standards before that, but I don't know what they were.

I dug a little more and I find C24000 "Low Brass" at 78.5-81.5 Cu and C25000 "Brass" (yep, just "Brass") at 74-76 Cu. I'd be willing to bet that the Buescher factory used one of these, of course in the 30s it would have been called something different, but the basic alloys of most metals have persisted just under different designations.

 

[David Dorning]

Well, I'll readily admit I don't know about copper alloys that might have been in common use in the 1930s. That's well before the UNS which appears to have been instituted 1974. Of course there were standards before that, but I don't know what they were.

I dug a little more and I find C24000 "Low Brass" at 78.5-81.5 Cu and C25000 "Brass" (yep, just "Brass") at 74-76 Cu. I'd be willing to bet that the Buescher factory used one of these, of course in the 30s it would have been called something different, but the basic alloys of most metals have persisted just under different designations.

That's interesting, Low Brass sounds very close to the Buescher composition.

 

[Dr G]

Thanks for doing this, David. It’s interesting to see the numbers.

Regardless of composition, the analysis won’t tell us the hardness of the brass, which is a function of processing, nor indicate its thickness, which also has a direct bearing on its functional strength.

A deeper dive would include hardness values and grain size measurements, but that gets into destructive testing.

 

[David Dorning]

Thanks for doing this, David. It’s interesting to see the numbers.

Regardless of composition, the analysis won’t tell us the hardness of the brass, which is a function of processing, nor indicate its thickness, which also has a direct bearing on its functional strength.

A deeper dive would include hardness values and grain size measurements, but that gets into destructive testing.

Exactly - this just tells us something about the material the makers started off with but nothing about the stresses they imparted during manufacture.

 

[turf3]

It's not just the work hardening and annealing that may have been done during the making of the horn tubes, it's also about the original work hardened condition - dead soft, quarter hard, half hard, etc.

 

[Woodpad]

A deeper dive would include hardness values and grain size measurements, but that gets into destructive testing.

Due to differences in structure brass has a wide range in elasticity as measured by the Young modulus.
There are some non-destructive measuring methods.

 

[Dr G]

Due to differences in structure brass has a wide range in elasticity as measured by the Young modulus.
There are some non-destructive measuring methods.

Whatever do you mean by that? What differences in structure are you referring to? Dislocation structures? Atomic matrix structure? Grain structure? Texture?

Beyond that, what does it matter in this instance?

 

[Woodpad]

What differences in structure are you referring to?

All of them. When you have a vibrating structure the elasticity is elemental in how the energy is converted.

 

[turf3]

Due to differences in structure brass has a wide range in elasticity as measured by the Young modulus.
There are some non-destructive measuring methods.

Actually, though I haven't checked the tabulated values, typically for a given family of alloys the modulus of elasticity varies very little indeed. For example, if it's steel, you may as well just assume E = 30,000,000 psi. Doesn't matter the alloy within the steel family; doesn't matter the heat treatment; it's all 30 million psi maybe +/- 1,000,000. Tensile and yield strength, yes; wide wide variation. But E is pretty much always the same for steel. I'd bet it's the same for "brass" alloys.

 

[turf3]

All of them. When you have a vibrating structure the elasticity is elemental in how the energy is converted.

OK, let's run that pop fly out. The sound of a woodwind instrument is created by standing waves of compression pulsations within the bore. What do you think the equivalent modulus of elasticity for air in uniaxial compression is, as compared to the modulus of elasticity of the brass forming the walls of the bore? I'm not going to calculate it for you, but if the difference is less than four or five orders of magnitude I'd frankly be astonished. Take a 1" diameter syringe full of air and push on the plunger and see how much displacement you can get; then take a piece of 1" diameter brass bar stock and push on the end of IT and see how much displacement you can get.

 

[mizmar]

I'd be interested in peoples views on what the important factors are when thinking about the material a sax is made off.
I'm no-ones mechanical engineer (except to 'er indoors, who's a humanities person).

My guess would be, given it's light and cheap enough;
1. that the material can be manipulated by man and machine into the shape of an instrument with sufficient precision to be basically in tune; and stay that way. e.g.
2. that the material is rigid enough so that through the usage cycle (taking out of the case, playing, marching, putting down, picking up, packing up, transportation etc) it doesn't twist or bend enough to put the tone holes out of alignment with the pads.

 

[turf3]

OK, a back of the envelope calculation indicates uniaxial modulus of elasticity for air (or any ideal gas) would be about 1.07 psi (at STP). For brass, approx. 14,100,000 psi.

So who here thinks that the material that's 14 MILLION times stiffer, is going to have any effect on the behavior of the air?

 

[turf3]

I'd be interested in peoples views on what the important factors are when thinking about the material a sax is made off.
I'm no-ones mechanical engineer (except to 'er indoors, who's a humanities person).

My guess would be, given it's light and cheap enough;
1. that the material can be manipulated by man and machine into the shape of an instrument with sufficient precision to be basically in tune; and stay that way. e.g.
2. that the material is rigid enough so that through the usage cycle (taking out of the case, playing, marching, putting down, picking up, packing up, transportation etc) it doesn't twist or bend enough to put the tone holes out of alignment with the pads.

Yep, that's pretty much it.

Thus C26000 for saxophone bodies. I didn't see where the XRF analysis of "key material" was done. If it was on the key cups then the apparent use of C26000 for those would make sense as they have to be formed into the cups. If I had to hazard a guess for rods and key arms I'd guess C36000 for its improved machinability.

 

[Dr G]

All of them. When you have a vibrating structure the elasticity is elemental in how the energy is converted.

You are blowing smoke.

I was hoping that you knew something about “vintage” manufacturing techniques that you could share.

 

[mizmar]

.... Also I guess it shouldn't be so brittle that it cracks under expected environmental assault (change in temperature, getting knocked) so we get dings and dents rather than cracks?

 

[Dr G]

OK, a back of the envelope calculation indicates uniaxial modulus of elasticity for air (or any ideal gas) would be about 1.07 psi (at STP). For brass, approx. 14,100,000 psi.

So who here thinks that the material that's 14 MILLION times stiffer, is going to have any effect on the behavior of the air?

Hmm, wouldn’t that depend on which way the wind is blowing???

Thanks for being here, Turf3. As always, I appreciate what you bring to the conversation.

 

[Dr G]

.... Also I guess it shouldn't be so brittle that it cracks under expected environmental assault (change in temperature, getting knocked) so we get dings and dents rather than cracks?

We are getting back to the classic “Selection of Materials” case study that proves time and again that brass was, and remains, the right choice for saxophones.

 

[mizmar]

We are getting back to the classic “Selection of Materials” case study that proves time and again that brass was, and remains, the right choice for saxophones.

Well, yes. I was wondering where "resonates around 440Hz" comes in... If anywhere

 

[Stephen Howard]

I'd be interested in peoples views on what the important factors are when thinking about the material a sax is made off.
I'm no-ones mechanical engineer (except to 'er indoors, who's a humanities person).

My guess would be, given it's light and cheap enough;
1. that the material can be manipulated by man and machine into the shape of an instrument with sufficient precision to be basically in tune; and stay that way. e.g.
2. that the material is rigid enough so that through the usage cycle (taking out of the case, playing, marching, putting down, picking up, packing up, transportation etc) it doesn't twist or bend enough to put the tone holes out of alignment with the pads.

A primary factor has to be ease of repair (which also ties in with ease of manufacture).
Things have to be fitted to the body such that they are strong enough to withstand use and (some) abuse.

 

[turf3]

Well, if you finger an indicated in-the-staff B on soprano, or first-ledger-line-plus-a-space B on tenor, or in-the-staff F# on alto, etc., then the air column of your saxophone will resonate at 440 Hz. (That's how woodwind instruments work.)