Roger Burdette's Saint Gaudens Double Eagles Book 4 4

[GoldFinger1969]

On 9/29/2024 at 9:23 PM, Henri Charriere said:

There appears to be a positive correlation between the number of posts on this Topic and the prevailing spot price of gold. 2,600+  Keep those posts coming!  

Well, it would be indirect if anything.  I would think the threads on Gold Price Forecasts would get most of the action, only to the extent that folks are looking at Saints as gold rises would this thread be relevant.

[GoldFinger1969]

On 9/30/2024 at 3:44 AM, dcarr said:

You can not determine what type of press was used based solely on the "sharpness". The strike fullness can indicate the tonnage applied, and possibly infer what type of press was used.  But "sharpness" is a function of the dies more than the press. If a piece is fully struck at 200 tons on a standard production press, and then the same dies are employed to strike another piece at 200 tons on a medal press, there will be no discernible difference between the two pieces. 

There were only a few presses employed at that time that struck gold coins and/or Saint-Gaudens DEs.

So I would guess Roger narrowed it down based on the strike.

[RWB]

On 9/30/2024 at 11:06 AM, GoldFinger1969 said:

There were only a few presses employed at that time that struck gold coins and/or Saint-Gaudens DEs.

So I would guess Roger narrowed it down based on the strike.

Each of the mints had at least 3 large presses used for striking S-G double eagles. All were toggle presses although we do not as yet know how many had fixed vs cycling lower die stakes. Completeness of detail is determined by die condition, planchet hardness, and pressure. This is clearly illustrated in the Morgan dollar series, where we have ample documentation and a large body of extant pieces.

RE: "If a piece is fully struck at 200 tons on a standard production press, and then the same dies are employed to strike another piece at 200 tons on a medal press, there will be no discernible difference between the two pieces."

The above quote is incorrect. Although dies and force might be the same, the manner of force application differs considerably. Metal movement, crystallization, boundary formation, shock wave propagation, etc. on a time graph all differ between toggle and hydraulic medal presses. The resulting coins will appear identical to the untrained, but they will have consistent differences upon careful examination. (I.e., an abrupt blow and a 'lengthy' squeeze are not the same.)

[Henri Charriere]

On 9/30/2024 at 11:04 AM, GoldFinger1969 said:

Well, it would be indirect if anything.  I would think the threads on Gold Price Forecasts would get most of the action, only to the extent that folks are looking at Saints as gold rises would this thread be relevant.

🐓: Yeah, so how come you chose this thread over the other one?

Q.A.:  Easy, this one's got 2,600 posts. The other one doesn't.

🐓  :  You mean you cheated just to get your point across?

Q.A.  Yup, always do!  🤣

[GoldFinger1969]

On 9/30/2024 at 12:13 PM, RWB said:

RE: "If a piece is fully struck at 200 tons on a standard production press, and then the same dies are employed to strike another piece at 200 tons on a medal press, there will be no discernible difference between the two pieces."

The above quote is incorrect. Although dies and force might be the same, the manner of force application differs considerably. Metal movement, crystallization, boundary formation, shock wave propagation, etc. on a time graph all differ between toggle and hydraulic medal presses. The resulting coins will appear identical to the untrained, but they will have consistent differences upon careful examination. (I.e., an abrupt blow and a 'lengthy' squeeze are not the same.)

You would think sometime over the decades someone at the Mint might have said how do 2 coins, same composition of metal, look when struck with the SAME dies but DIFFERENT presses ?

Was this ever done ?  

[GoldFinger1969]

1908 No-Motto MS-64:  Saw an infomercial over the weekend.  Didn't like the continued "rare" references based on total mintage of over 70 million....0.2% etc.....well, even 0.2% is 140,000 coins.  That's ALOT !!!  Esp. when the Registry+Type base are 50,000 tops which means the excess must be absorbed by the Investor class.

Which it was targeted at.....for $4,000.....when gold (in the infomercial and at the time of film editing) was just above $2,500.  For an MS-64, no Wells Fargo pedigree, that's a HUGE (obscene ?) premium to FMV.  I think you can probably get an MS-64 for about $2,700 or less when the gold price is at $2,500.  The show focused on ebay OFFERS for non-completed sales and used them as comps. 

Very deceptive. 

 

Edited Tuesday at 02:39 AM by GoldFinger1969

[dcarr]

On 9/30/2024 at 10:13 AM, RWB said:

RE: "If a piece is fully struck at 200 tons on a standard production press, and then the same dies are employed to strike another piece at 200 tons on a medal press, there will be no discernible difference between the two pieces."

The above quote is incorrect. Although dies and force might be the same, the manner of force application differs considerably. Metal movement, crystallization, boundary formation, shock wave propagation, etc. on a time graph all differ between toggle and hydraulic medal presses. The resulting coins will appear identical to the untrained, but they will have consistent differences upon careful examination. (I.e., an abrupt blow and a 'lengthy' squeeze are not the same.)

.

I absolutely disagree.

1) Crystallization. This is an aspect of the metal in a planchet prior to striking. Crystallization does not occur during the striking. It only occurs when molten metal solidifies (the slower the cool-down time, the more crystallization there will be). When using the same planchet and the same dies on two different presses, crystallization in the planchet will make no difference when comparing strikes by the different types of presses.

2) Boundary Layer Formation. This is a characteristic of fluid dynamics. There is really no such thing as room temperature "metal flow". Solid metal will bend, stretch, and buckle, but it does not "flow".  Boundary Layer Formation does not apply here because the shear strength of fluids is extremely low, while comparatively, the shear strength of metals (even soft types) is high.

3) Metal Movement and Shock Wave Propagation.

These are basically the same thing. The crux of the matter is the contention that the slower speed of a medal press will make a difference compared to the higher speed of a standard mechanical press (also known as a "toggle", "knuckle-joint", or "flywheel" press).

The important factor (and the only appreciable difference between the two types of presses) would be the strike dwell time. With a slow hydraulic "medal" press, when maximum tonnage is reached, the hydraulic pump will maintain the striking force for as long as the operator leaves the pump running. This could last a few seconds or more. With a standard mechanical press, the dwell time is shorter. Would that make a difference ? (answer below):

My circa-1986 mechanical Gaebener press (Denver Mint surplus) can strike about 10,000 pieces per hour, which is a faster rate than Double Eagle presses that the US Mint would have used. The stroke length (the total distance that the die moves down per strike) is 50mm. This is 500,000mm per hour that the die is moving down. But half the time the die is moving up (retracting). So the approach speed of the die is twice that, or 1,000,000mm per hour. This is just over 275mm per second (1,000,000/3,600 = 277.77). So, at full speed, my press will push the die towards the planchet at about 275mm per second. A standard Saint-Gaudens Double Eagle has a relief height of about 0.015 inch. A high-relief version, almost 0.030 inch (about 0.75mm). At 275mm per second, it would take the die (0.0027) of a second to form the strike. In other words, the dwell time that the die is penetrating into the planchet is 0.0027 second. Now the question is, how much of that 0.0027 seconds is spent at maximum tonnage. Since my press is powered by a massive flywheel, the maximum tonnage is instantaneous at one specific point on the flywheel rotation. For the sake of my calculations, I will use plus-minus one degree of flywheel rotation. this would be a minimum of 99.98% of the maximum tonnage ( SIN(89) = 0.9998 ). So 2 degrees out of 180 degrees would be 1/90 of the total travel time spent at (or very near) maximum tonnage. This is a very short time of about 0.0003 second (.0027/90)

The speed of the shock wave propagation is the same thing as the speed of sound in solid metal. Softer metals have a slower speed of sound. For my estimate calculations, I will use pure gold which is slower than .900 gold.

The speed of sound in gold is 3,240 meters per second. This is 3,240,000mm per second. The diameter of a Saint-Gaudens Double Eagle is 34mm). The distance from the center of the planchet to the edge is half that (17mm). So the time that it would take a shock wave to propagate from the center of the planchet to the edge is 17/3,240,000 = 0.00000525 second. This would be equivalent to about 190,600 oscillations per second. In 0.0003 seconds (the dwell time at maximum speed and maximum tonnage on my press), a shock wave would oscillate back and fourth more than 57 times. At each oscillation, the wave intensity diminishes. With a vintage US Mint mechanical press, it is likely that the shock wave propagation would oscillate more than 100 times at maximum tonnage.

If the striking was so fast that the shock wave would only reflect back and fourth perhaps 3 or 4 times, I could see there might be some difference between a relatively slow strike and the super fast strike. But with 57 oscillations (at a minimum), there would be no difference between this and a longer dwell time.

.

 

Edited Tuesday at 08:30 AM by dcarr

[GoldFinger1969]

On 10/1/2024 at 4:29 AM, dcarr said:

1) Crystallization. This is an aspect of the metal in a planchet prior to striking. Crystallization does not occur during the striking. It only occurs when molten metal solidifies (the slower the cool-down time, the more crystallization there will be). When using the same planchet and the same dies on two different presses, crystallization in the planchet will make no difference when comparing strikes by the different types of presses.

I'm not an expert here by any stretch, so I want to be careful here entering the arena between 2 giants.

However, from the book upon which this thread is based....the entire luster variable is a function of the microscopic deformations at the molecular level as the die hits the metal and great heat and pressure are brought to bear.  So crystallization, deformation, and other metallic changes occur at the atomic or molecular or chemical level which affect composition, appearance, surface texture, looks, etc.

Again, the exact description is covered in the book and maybe RWB's RoAC series.

[RWB]

On 9/30/2024 at 10:26 PM, GoldFinger1969 said:

You would think sometime over the decades someone at the Mint might have said how do 2 coins, same composition of metal, look when struck with the SAME dies but DIFFERENT presses ?

Was this ever done ?  

If you mean toggle vs hydraulic, I've seen nothing to suggest any such tests or examination was done. But, we are missing almost all of the routine documentation of the Engraving Department (and all other department records except assay and some M&R). Mint documents show consistent concern about the visual appearance of coins, and the importance of consistency as part of anti-counterfeiting activities.

[RWB]

On 10/1/2024 at 10:57 AM, GoldFinger1969 said:

Crystallization does not occur during the striking. It only occurs when molten metal solidifies

No. Mr. Carrr is incorrect. You are thinking only of initial crystal formation during phase change. Metal crystals are dramatically affected by force applied to metal as well as alloy consistency. Alteration of metal crystals is the primary reason for various heat treatments.

Edited Tuesday at 03:16 PM by RWB

[GoldFinger1969]

LUSTER:  From P. 633 of Roger's book, since we are talking about striking, dies, metal composition, and the like. 

"Luster, as understood by coin collectors, is the visual result of light reflecting off of thousands of tiny ridges and grooves of metal in the smooth (i.e., field) areas of a coin. These imperfections were created in a working die as the hard steel was stressed during the striking of thousands of blank planchets.

The original surface of a coinage die is smooth, somewhat satin-like and largely free of imperfections.  This die face is made of very hard carbon steel (mostly martensitic steel formed by rapid cooling of austenite steel) that has been tempered for toughness.  Modern techniques further harden the surface through applications of special coatings, but this was not done on dies made for Saiunt-Gadudens double eagles.

In use, the hard die face impacted a soft medal planchet composed of 0.900 gold and 0.100 copoper.  The pressure, or force, applied to the planchet was approximately 100 tons to 120 tons per square inch acting over a short period of time.  The energy of the blow pushed planchet metal into the recesses of the die so that the coin became a mirrror image of the die face.  With each blow of the die, an imperceptible movement occurred in the crystals of the die face.  Following several hundred strikes, the die face had distorted slightly so that the the fields were no longer completely smooth but consisted of microsopic ridges and grooves.  These radiated from the center of the die face and also emulated the general pattern of metal flow in the planchets.  Once metal flow was established, it tended to aid metal flow in planchets and the die surface then changed very slowly.

This type of surface alteration was most prominent in the fields of a die where movement of metal was grreatest and least inhibited by details of the design.  The portrait, inscriptions, and other design elements were subject to similar die deformation, but at a much lower rate and magnitude.  This explains why a coin shows luster in the fields but not in the raised areas."

[GoldFinger1969]

Just so everyone is clear:   Roger was quoting Dcarr and not me in the quote on molten metal.  I was quoting Dcarr and Roger than quoted me quoting him (hence why it looks like it's my direct quote ).

Edited Tuesday at 07:12 PM by GoldFinger1969

[dcarr]

On 10/1/2024 at 9:14 AM, RWB said:

No. Mr. Carrr is incorrect. You are thinking only of initial crystal formation during phase change. Metal crystals are dramatically affected by force applied to metal as well as alloy consistency. Alteration of metal crystals is the primary reason for various heat treatments.

No, crystals do not form during striking. The planchet metal, and any crystals within, are deformed by striking. Just like non-crystalline metal is also deformed by striking.

The point of this discussion is that crystals in a planchet will strike the same on either type of press (with sufficient tonnage).
So, contrary to your contention, crystalline planchets do not favor one type of press over another.

Heat-treatments (for hardening dies or softening planchets) also do not favor one type of press over another (given the same dies, planchets, and tonnage). Heat does not come into play at all during fast or slow striking (unless something has gone wrong). A coin struck with 300 tons of force will come off the press and still be the same room temperature. The only time a struck piece gets hot is when it is a very large broad-strike with a lot of metal distortion and stretching. But even then, it will be about like handling a hot potato (not hot enough to boil any water even if immediately submerged).

 

 

[dcarr]

On 10/1/2024 at 8:57 AM, GoldFinger1969 said:

I'm not an expert here by any stretch, so I want to be careful here entering the arena between 2 giants.

However, from the book upon which this thread is based....the entire luster variable is a function of the microscopic deformations at the molecular level as the die hits the metal and great heat and pressure are brought to bear.  So crystallization, deformation, and other metallic changes occur at the atomic or molecular or chemical level which affect composition, appearance, surface texture, looks, etc.

Again, the exact description is covered in the book and maybe RWB's RoAC series.

 

See my comments about heat in my post just prior to this one.

 

[dcarr]

On 10/1/2024 at 1:10 PM, GoldFinger1969 said:

LUSTER:  From P. 633 of Roger's book, since we are talking about striking, dies, metal composition, and the like. 

"Luster, as understood by coin collectors, is the visual result of light reflecting off of thousands of tiny ridges and grooves of metal in the smooth (i.e., field) areas of a coin. These imperfections were created in a working die as the hard steel was stressed during the striking of thousands of blank planchets.

The original surface of a coinage die is smooth, somewhat satin-like and largely free of imperfections.  This die face is made of very hard carbon steel (mostly martensitic steel formed by rapid cooling of austenite steel) that has been tempered for toughness.  Modern techniques further harden the surface through applications of special coatings, but this was not done on dies made for Saiunt-Gadudens double eagles.

In use, the hard die face impacted a soft medal planchet composed of 0.900 gold and 0.100 copoper.  The pressure, or force, applied to the planchet was approximately 100 tons to 120 tons per square inch acting over a short period of time.  The energy of the blow pushed planchet metal into the recesses of the die so that the coin became a mirrror image of the die face.  With each blow of the die, an imperceptible movement occurred in the crystals of the die face.  Following several hundred strikes, the die face had distorted slightly so that the the fields were no longer completely smooth but consisted of microsopic ridges and grooves.  These radiated from the center of the die face and also emulated the general pattern of metal flow in the planchets.  Once metal flow was established, it tended to aid metal flow in planchets and the die surface then changed very slowly.

This type of surface alteration was most prominent in the fields of a die where movement of metal was grreatest and least inhibited by details of the design.  The portrait, inscriptions, and other design elements were subject to similar die deformation, but at a much lower rate and magnitude.  This explains why a coin shows luster in the fields but not in the raised areas."

This is not the complete story.

Even if brand new dies with no luster on their surfaces are utilized, the very first strike from those dies can generate a piece with significant mint luster. The formation of mint luster has as much to do with the radial expansion of the planchet when struck, as it does with the texture of the die surfaces.

If a planchet is loose fitting in a collar, it will have more room for radial expansion and so it will have more mint luster when struck. Conversely, a planchet that is tight in the collar will not have as much radial expansion and will be struck with a lot less luster.

The main reason that proof coins are multi-struck is not to bring up the details. The first strike causes the planchet to expand radially up against the collar. And after this first strike the coin will have radial mint luster to some extent despite the dies being polished. But since almost all of the radial expansion occurs on the first strike, subsequent strikes have the affect of imparting the polished nature of the dies onto the coin because it is not expanding in diameter any more.

"This type of surface alteration was most prominent in the fields of a die where movement of metal was grreatest and least inhibited by details of the design.  The portrait, inscriptions, and other design elements were subject to similar die deformation, but at a much lower rate and magnitude.  This explains why a coin shows luster in the fields but not in the raised areas."

This statement (above) is not completely correct. While it is true that the fields of a coin exhibit the most luster, it is not that way because of details in the engraving that inhibit or interrupt metal movement. The reason that the fields have more luster is because that is where the highest stresses are. Luster is a form of metal stress. It is not as much a function of the (inaccurate term) "metal flow". The fields on a die are the highest parts of the die face, and these are the areas that penetrate the deepest into the planchet (and thus, experience the greatest stress).

[Henri Charriere]

🐓 :  Say, Quintus, what do you make of all this?

Q.A. :  It's hard to say, Ricky.  One member has hands-on experience with the coin-making process while the other has studied the subject in depth since the 20th President had an encounter with destiny in Washington, D.C.  I would venture to say this segment of the long-running thread is not unlike a tutorial.

🐓 :  You mean like, "Everything you always wanted to know about the Original Mint Luster on your MS-67 coin"?

Q.A.:  Pretty much.  What I do -- and have done my entire life -- is familiarize myself with each of the dueling viewpoints.  The Absolute Truth lies somewhere betwixt the two.  There are two sides to every story, and very often a third side.  This is what the Forum is all about and does best.  I wish I were more knowledgeable about the subject at hand.  Maybe this will whet my appetite to explore this in further detail.