I get a little dizzy looking at the eagle:

1840 rouble

Now I know that pre-1844 roubles were technically not struck as well as later coins, and that they used a die until it fell apart. I have some Russian coins with similar die cracks. But what would cause the swirly shape of the letters? Is this also due to die polish and/or wear? Has anyone seen anything like this before?

That is more significant than die polishing, more like something like die rotation whilst the coin was struck. But I cannot imagine how that could happen.

There are 6 significant die cracks on the reverse of the piece, yeppers, I am guessing this was one of the last from this miserable die before it gave up the ghost.

On first glance it does appear to be an over-zealous mint worker polishing the reverse
die. However Scottishmoney has a good point in that something else may have affected
the strike as well.

My inclination, however, is to think that most of the problem is due to the die polishing.

RWJ

Rotation of a die or coin during the very moment of strike. Note that letters are more "swirly" closer to periphery. Also during rotation metal in the surrounding fields was displaced and they look rough (it has nothing to do with die polishing).

WCO

I wonder how the die was rotated so violently, so much so that it blurred the lettering, this has to have happened as the die was being applied to the coin - like Ivan got pissed because he didn't get a potty break or something and decided to take it out on the coin.

Press has rotational momentum, it tends to rotate both upper die and therefore coin during strike.

WCO

Some interesting theories have been stated here. However, there are still some puzzles:

(1) Eagle and emblems show no signs of such motion. Otherwise, if the whole die (or planchet) were turning during the moment of strike, the eagle design should also show some signs of it, even if a bit less than on the lettering;

(2) The eagle and emblems show little sign of die polish, too;

(3) It appears to me that the distortion of the vertical elements of the letters is too great to have been caused by die polishing alone.

Now what about this theory:

(1) In order to strike the die from a hub (or from various hub pieces, as was common before ca. 1844), the die must first be heated (i.e. softened, then later annealed) to a point where it is possible to strike steel against steel without breaking the die or the hub ... the hub, after all, is also made of steel.

(2) Let's assume that the lettering was sunk into the die FIRST, before the eagle design! For obvious reasons, I believe that mostly it was done in the opposite order: First the intricate eagle design, then the lettering (the design having more detail should be done first; sinking the lettering, with the simpler design, could also occur at a later stage when the die was a bit colder). Of course, I'm no expert at die sinking ... maybe I have it backwards? But experience shows that many coins struck before this period also had convex planchets, which would mean that the eagle (i.e. whatever was in the middle of the coin area, as opposed to the parts near the edge) would have come in contact with the die first -- not the other way around (unless the die was constructed concavely, such that the force of the strike made the coin convex...in this case, the outer parts of the coin would indeed hit the die first... ).

Anyway, it LOOKS like the metal was still flowing when the letters were sunk, and not flowing when the rest of the coin was done. If the metal of the die was soft enough to distort the letters to such an extent, it could have cooled off enough to allow for a clean strike of the rest of the die -- assuming that the letters were struck first.

But there is something wrong with this theory as well: In 1840, the lettering was still applied piece-meal to the dies; even single letters were composed out of parts (thanks to RW Julian for this information!) If my theory were true, it would mean that all of the lettering would have had to be on a hub and sunk into the die as a unit! Perhaps they were experimenting with this technique as early as 1840?

What do you think??

May be my little theory is questionable, but here it is.

Upper die was turning during striking. Since there is no weakness in strike at the central part of the coin possibly all the metal flaws there were "repaired" by the farther movement of the die. Not the same is at periphery. It seems there was not enough metal to fill all the small elements of the die, even denticles at the border are missing and letters are weakly struck, so the die was unable to "repair" metal flaws resulted from its early movement into the body of planshet. This may be also true if there was not enough pressure to make fully struck coin.

WCO

Hi Guys,

Been away while RW Julian and I worked on a couple projects for RNJ and Numismatic News. Bob told me about this piece. Since minting tech is my thing, he asked that I comment.

First off, the die(s) were not rotating. Here's a couple points:

1. Note that the flow pattern does not materially affect the bottoms of the letters nor the beading around the eagle. If the die really was rotating during impact, these would likewise be affected, as would the central eagle device albeit to a lesser extent.

2. At the moment of impact there is a very large force applied along the vertical axes of the dies. Even if the dies were loose this would effectively lock the dies in that position for the remainder of the strike. It would thus take a rotational force in excess of the vertical force to rotate the dies during strike. If one looks at the engineering drawings of the Boulton press (see Cooper) there is no potential causitive factor for such a large rotational force. In sum, proposing that the dies were rotating during the strike is analagous to proposing that one could rotate a CD with a 2 ton truck sitting on it. For those who doubt this, the solution is simple: draw a free-body diagram and then calc the forces. Sorry, ain't gonna happen, its physics 101.

Nor is this die polishing or die sinking related. OK, so what is it? It's very heavy metal flow arising from worn and misaligned dies. The planchet may aslo have been poorly annealed.

This type of metal flow is not uncommon in coinage, or any stamped or rolled metal for that matter. It is rather common on US, esp. Capped Bust Half Dollars, Large Cents, etc., in sum all of the screw press coinage were the strike is an impact strike. This type of strike has specific metal flow characteristics, one of which is very heavy peripheral metal flow once the dies wear and being to loose their "basin" or buckle. This wear reduces the amount of pressure at the periphery resulting in the metal only partially being constrained by the peripheral elements. As a result you see heavy flow lines off the tops of the peripheral elements. (BTW, the Boulton press was a screw press, it was merely powered by a steam engine rather than by hand. Thus the strike charateristics are screw press, just heavier than a manually driven one.)

The "twist" is certainly interesting although I've seen it before, just not to this extent. Very cool. This was probably caused by the misalignment of the dies (note the heavier strike at the dentils on left), the dies wear/damage, possibly combined with a poorly annealed planchet. Also note that the obv shows similar flow lining under the wreath to the right of the bow.

Be aware that the heavy flow lines are a solely an artifact of the planchet metal flow. These lines do not show on the die itself. Numismatists once thought that these lines were "gouged" into the die by the constant erosion of the planchet metal flow. However, the US 1806 Half Dollar obverse die in the ANS collection disproved this. Late state coins struck for this die show very heavy flow lining at the periphery, but the die itself shows no such lines. Rather it shows just fairly heavy overall wear.

Hope this helps with the discussion and that I've answered to eveyone's satisfaction. Very cool coin. I'd strongly suggest a bid for those who are advanced collectors. Unless there are a lot of late state pieces of this variety I doubt you'll find another like this anytime soon.

ugh i feel dizzy...makes me feel like i just got off the tilt-a-whirl

Thank you for the comments, rittenhouse. Very interesting and informative as always.



Please explain how screw press works so I can understand how it is possible to move die up and down without rotation involved.

If there would be ONLY one force involved there would not be swirly flaws of metal how we see them. They show exactly how the powers were applied. Flaws of metal in the case of strictly vertical power would go from centre to periphery as straight lines. So there definitely was "second power". Correct me if I am wrong.

What possibility I missed is that die could be misaligned (not parallel to a planshet) and may be that was the source of "the second force" present during strike. However, in this case "twists" or "swirls" would be much heavier on one side of the coin than on the other and their direction and form would be different and I do not see it. Weakness of strike should be very dramatic on one side of the coin too and it is not also the case. What do you think?

In any case there were two powers involved and what we see have nothing to do with die polishing.

I also want to add, this coin is not something never seen, many 1830-s early 1840-s Rubles have about the same look, may be not this dramatic but still.

WCO

Thanks to both of you, WCO and rittenhouse.

I agree that elements of this kind of error are seen on lots of coins -- however, it is unusual that a coin with this kind of mint "errors" would exist in such a well-preserved state WRT circulation. It is indeed "AU", IMHO. As such, it is a highly desirable coin, but even more interesting for the fact that it was struck at such a late die stage (and that it is possible to tell the difference so clearly between circulation wear and striking features).

Thanks guys, very interesting.

Here is one of the latter die state but not as dramatic as the one in the link:



sorry, the lighting is terrible. It's a 1842 ruble by the way.

Thank you for this explanation. It is indeed helpful.

I think this might make a worthwhile article for an upcoming JRNS (hint, hint).

Neat coin, gx!

Neat coin gx, with a much more typical metal flow from the tops of the letters. The metal flow will vary in strength and direction due to a number of factors including die wear, die buckling, strike pressure, planchet hardness, position of devices, size of devices, etc.

Edited to add:

While flow lines are far more common on late state, I have also seen flow lines on earlier state coins. The cause is poor die pressure and/or poor basining of the dies.

WCO,

How a screw press operates without the uppper die turning is simple: the die is fixed to the upper die block, also called a slider. The block is held against the screw by various mechanical arragements including S-leaf springs, counter-weight and lever, or torsion isolation assembly. This isolates the upper die from the rotation of the screw. These are clearly shown in the photos and contemporary engineering drawings in Cooper.

For a further understanding I'd suggest you get a copy of Cooper. However, even this work is not complete enuf to answer the question as he does not go into metal flow mechanics. For this info you would need to consult several mechanical engineering texts. The Metals Handbook would be a start. A background in mechanical engineering helps (I was a Process and Quality Engineer in the metals forming industry).

Oh great, now Julian will be on the phone bugging me for another article!....... Just kidding. I'll see what we can do. Either the journal or the newsletter.

Thank you Rittenhouse. interesting and well said explanation. Does anyone have a source for this Cooper book? (Im assuming its The Art and Craft of Coinmaking; A History of Minting Technology .

Couldnt find it on the www. PM me, anyone, if youve got a copy for sale.

Thanks for suggesting literature, rittenhouse. I am not familiar with mechanics of a screw press of that time, once I find some time I will look into it. I appreciate the advise.

However, I am familiar with first law of Newton. Newton's First Law states that any object in a state of rest or moving in a straight line (uniform linear motion) tends to remain in such a state unless acted upon by an external force. So during strike there must be another force to produce non linear flows of metal. So what do you think what was the source of that second force if it was not an upper die?


WCO

Hi rittenhouse. Can you tell me the title of Cooper's book as I would be interested in reading it.

Thank you,
Hus

Squirrel got it. It's "The Art and Craft of Coinmaking; A History of Minting Technology" by Denis Cooper. Denis is a former Chief Engineer of the Royal Mint. After retiring he formed a firm specializing in minting equipment. I had the good fortune of personal contact w/ Denis in the early 1990s. He's very sharp on minting tech and a wealth of info. His book is THE reference for thos interested in historical minting technology. It's out of print but you can occassionally find copes on eBay or ABE Books.

My, my. You think yourself terribly clever. However, you just outwitted yourself again (obviously not a difficult task).

Even if Newtonian mechanics applied here (which it doesn't) amateur-hour pseudo-scientists always forget to read the little cavet published in most texts: the laws and equations are presented as idealized for general principles and do not take into account the effect of friction. So, even if Newtonian mechanics applied, you forgot FRICTION - the friction of the planchet against the dies and the friction of the molecules of the planchet against each other as the planchet deforms .

BTW, Newtonian mechanics only deals with the motion of macroscopic objects. This is the wrong area of physics to describe the deformation of materials under pressure. Look it up in wiki.

So, to your lack of knowledge of the presses, you can add a lack of knowledge of mechanics. Suggest you do A LOT of reading and study before you post again.

Is it really necessary to be rude?

Until this last reply I thought this was one of the best threads we have had in a long time. It was extremely interesting, with a lot of great information and a civilized exchange of ideas and opinions.
But we simply couldn't keep it up could we?

How very very sad.

Maya,

From WCO's wording and emoticon I took it that he was trying to be smart with me as he sometimes is. I do not appreciate that. Had he simply asked the question w/o trying to show his cleverness he would have received a polite response.

I any case I apologize to you since you took offense.

Here are some more thoughts on the issue: No matter how Bolton press worked I still think that upper die could have an ability to rotate by by 2-5 degrees (plus or minus). One out of many reasons is that a die may become loose and there is no need to dig deep into mechanics of press to understand that. Speaking about "friction of the planchet against the dies" friction is not a force, it can't move anything by itself, especially large quantities of metal. There must be a force. And friction unable to change direction of movement of large quantities of metal (assuming that friction is constant), there must be another force. If you remove a die from press and lay it down on a planshet there will be friction (friction at rest). But there will be no coin struck, no metal moved. For that you need force. About molecular friction, I think it is not molecular level (may be I am wrong, then correct me), metal was moved in large quantities, laws other than on molecular level are in force here.

regards,
WCO

Think of it like putting a piece of wood into a bench vise. You turn the handle and squeeze the vise, The handle goes around and around, but the vice only squeezes the wood, the vice jaws do not turn.

Thank you.

I obtained my copy from Charles Davis (a Massachusetts book dealer,
specializing in numismatics) in 1994 and he no doubt has a copy from
time to time for sale.

It is a book well worth owning for anyone interested in the technical end
of coinage.

RWJ

Hello, People! Maybe all of this coins just a bunch of fakes. Take the look at the rims. Thks. M.

mummytrol, if you are talking about the excessive "cud" on the edges, it's actually rather common on coins from that era.

Here is another example:



edit: And guys, negative/unrelated personal comments are subjected to be removed / deleted and maybe warned. Negative comments are not very helpful to anyone here so please kindly be thoughtful to others. I personally don't want to do this but will if it keeps going at this rate. Thanks

I ment letters oh the edge. In that 1842 rouble what picture i put before they are not straight. Thank you. M.

But none of the edge lettering is visible in the picture you supplied...so what do you really mean???

I will try to do a picture. M.

WCO,

Since you have stated that you do not know how the presses functioned, what you "think" is invalid. It is an axiom of logic that one cannot argue from a point of ignorance. I will state again: The design of all presses, including Boulton's, is such that the dies do not rotate with striking. Squirell had an excellent analogy with his example of a vice. The slide mechanism is such that it effectively isolates the movable jaw from the torque. Screw presses are even more torque isolated since even the slightest rotation during strike would have disastrous shearing effects on the appearance of the devices. It it not necessary to take my word on this, anyone can easily check by getting a copy of Cooper or a few mechanical texts.

And, as I previously pointed out, even if the dies were loose in the die cups, as soon as the strike begins the loading effectively locks the dies in place for the remainder of the strike. As with press design, you do not need to take my word on this. There are many, many coins out there that are "rotated die errors". If the dies continued to rotate during the strike, these pieces would show shear effects on the devices. Since they do not, the empirical evidence is that the dies lock under load. If this is insuffcient, one need merely consult with the engineers from a private or public mint.

Further, the science of Physics does recognize friction as a force. Again, it is not necessary to take my word on this. Just look it up in wiki. In fact, here's the link: http://en.wikipedia.org/wiki/Friction. If you're suspicious of wiki, you can google it and find many, many refs from major universities saying the same. If you distrust that, you can simply order a decent text.

If you wish more information on the internal frictional and structural forces affecting the deformation of metal you can simply consult the appropriate metallurgical texts. The "Metals Handbook" I mentioned previously is a great place to start. You do need a fair understanding of mechanics and physics, though.

I believe that fully covers this subject unless others would like me to expand (within the limitatons of a BBS) on some technical point.

My apologies gx. I became irritated at WCO's smart-mouthing. Usually I find this sort of thing amusing, but this time it caught me. I'll do better in the future.

Those are nice coins. I like the Russian double eagle.

Rittenhouse,

Since you gave me wiki to read about friction, may I also use an article from the same source that is a bit more advanced than the article you gave:

http://en.wikipedia.org/wiki/Coefficient_of_friction

In that article it states that "It is important to note that in all cases, Newton's first law of motion holds". In ALL cases, in gases, liquids or moving particles of metal under pressure, in all and any objects. You told me that I "forgot FRICTION" but you did not explain what friction has to do with our discussion and how it may impact the ever holding "first law of motion".

May be I was not clear but under "force" I meant "external force", not friction as force. What prevents movement of metal inside blank is internal friction. Friction acts in direction against movement, and external force can change direction of movement.

We can endlessly engage into this and dig too deep. However, here is one point. You are not trying to explain the phenomenon but rather trying to criticize my theory here and there. By doing this we moved far away from the initial discussion. So far we only agreed that it most likely has nothing to do with die polishing.

Many rubles struck before the middle of 1840's had more or less the same look with crude flows of metal visible on the surface with naked eye, however just some of them had "curls" of metal and others had linear (straight) flows of metal. Once Boulton presses were removed from mint in 1845-1846 (and may be some other changes to technology) the quality of Rubles improved and there were no more coins with heavy flows of metal on the surface. So I guess everyone was expecting from you an answer to a question, what was "defect" in technology that sometimes produced "curly" patterns of metal on a coin. We are not talking about single Ruble, we are talking about quantities of both kinds of rubles, even though kind with linear flows of metal found more often. I provided my own "theory" of what happened, from the beginning stated that it is "questionable", you criticized my theory, fine I can live with that. Now it is your turn to tell your vision of issue. You only gave the info that "... twist... was probably caused by the misalignment of the dies (note the heavier strike at the dentils on left), the dies wear/damage, possibly combined with a poorly annealed planchet". Both kinds of coins with linear and curly patterns could have more weakness in strike in one "corner" of a coin and heavier strike in another "corner" of the same side. So at least a relation of die alignment to the form of those patterns is not that obvious, explanation is necessary. Dies wear/damage would mean that ALL next coins produced by this die should have about the same curls, since they also would be struck by the same worn/damaged die. Please provide more info how wear and what kind of wear of a die may result in "twists" of metal we are discussing.

I will appretiate if you will be able to also answer the following questions: 1. Should be there a difference (or there may be no difference) in external forces to produce curls of metal versus linear flows of metal? 2. What may be a source of such "additional" forces then (if any)? 3. What exactly resulted in such a pattern of metal on a coin and what was different from coins with linear flows of metal?

regards,
WCO

WCO - The mention of rotation of Boulton presses (dies) brought this English cartwheel to mind:




I hope this is relavent to the discussion.


Bill

Bill, thank you.

Interesting and unusual example, for sure it is relevant here. Unfortunately, pictures are not that good so I am not sure what kind of error it is. If it is a double strike than it proves only that die could rotate between two strikes, however rittenhouse insists that same kind of rotation is not possible during single strike, i.e. not possible to strike coin with twisting (rotational) move of a falling die. I do not know mechanics of a press so unable to check elements that would allow (or prevent from) this kind of move or something that would result in such a move, I have to trust rittenhouse expertise here. All I know is that plastic flow of metal in those coins (with curly flows) for some reason was different than in other "normal" coins (with linear flows) and I want to find the cause.
-------------------

On PCGS web-site I found definition for "flow lines": http://www.pcgs.com/lingo.chtml?Letter=F

flow lines - The lines, sometimes visible, resulting from the metal flowing outward from the center of a planchet as it is struck.
---------------------
So linear (straight) metal flow lines where "metal flowing outward from the center" are common, it is what one expects to see on a coin. Curved (twisted, curly) flow lines are unusual. Plastic deformation of metal there went differently than on other similar coins for some reason and I want to find out why.

WCO

WCO,

OK, I now understand what you're trying to get at. The answer is quite simple, but I doubt you're going to like it. Here it is anyway: UNKNOWABLE.

The problem is we have nothing to analyse. Oh yes, we have a PHOTO of a coin showing odd flow artifacts, but that's all we have. In order to fully analyse the effect we would need the original press, the original dies and the original planchets. The problem with engineering failures is that they are exceedingly complex. There are usually several competing forces and cascading effects. Very difficult to analyse. The I35W bridge collapse is a good example. It's been 4 months and they still haven't settled on the root causes. And they have the bridge, the cars and a video! We have nothing.

Absent the ability to fully analyse all the contributing factors the only thing we can do is iterate the general causes of this type of defect and postulate based on the photo. I attempted to do that in my initial post. Perhaps I wasn't clear. Let me expand:

1. Flow lines are caused by the movement of metal. Metal will flow away from point of highest pressure.
2. Due to variation in the dies (high and low points), curvature of the dies and devices cut into the die, there are many points of high and low pressure across the surface. Thus the planchet metal may or may not flow in the idealized "radial pattern".
3. Die wear, cracks and buckling of dies alter the die shape and thus the flow.
4. Position, size, depth and direction of the devices will affect the flow.
5. Strike pressure affects the flow.
6. Planchet hardness affects the flow.
7. Parallelism of the dies affects the flow.
8. Frictional forces affect the flow.


We also know that heavy flow lines of this type are seen in low pressure strikes or late state coins with very worn and degraded dies. The dies in this example are late state and quite worn and degraded. We can also see that the dies are out of parallel. This led me to postulate that the twisting lines were caused by the misalignment of the dies and the die wear, possibly combined with a poorly annealed planchet.

I did forget to add one thing though. Documents in the Boulton archives show that Boulton's engineers were critical of how the Russians made the dies. They felt the die forgers and engravers did not follow the best practices and made relatively poor dies. So, we can add this as a possbile cause. However, we should see evidence of that on earlier state examples.

Anyway, there's your answer. Beyond this point the only thing you can try is to come up with the original dies and the press, or at least a reaonable full-scale reproduction of such, and run experiments. Of course you could just accept that you know the generalities and leave it at that. That's what I do. Figure it out to a point of reasonable knowing. Otherwise you're just gonna work yourself into a tizzy over nothing knowable. No thanks. Me? I'm gonna go play some golf.

BTW, you said: "do not know mechanics of a press so unable to check elements that would allow (or prevent from) this kind of move or something that would result in such a move, I have to trust rittenhouse expertise here." Actually you don't. I rarely ever make a statement without providing easily checked references. Just get the books. If you can't find Cooper, Boulton's engineering drawings were also published in the 1815 American Edition of the New Edinbugh Encyclopedia. In sum, the info is out there, all you gotta do is look.

That's the easy answer: UNKNOWABLE. You should say it from the beginning, strange only that you are pretty sure that it may be anything but not a complex movement of a die under more than one force. I though that may be there was a research for similarly looking coins, not necessarily Russian (with non linear flows of metal) and you are aware of it.

Anyway, thank you for your time and replies and pls. forgive me if you found something wrong in my posts.

Regards,
WCO

Your post indicates that you still don't get it. The cause(s) can not be known with the SPECIFICITY you desire. That is, we cannot state that Y and Z caused a pressure gradient of X in this area which in turn caused the curving flow lines. However, we can know what does and does not cause flow lines within the general parameters of coining by screw press. That is what I said in the beginning.