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Anyone have photos of Bust coinage with roller marks?
Realone
Posts: 18,519 ✭✭✭✭✭
I would love to see exactly what that looks like, thanks if you do!
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It is assumed that the surfaces of the rollers in the rolling mill were generally smooth, even polished, at least when new, leaving a smooth finish to the planchet strips, whereas the files used during the planchet adjustment process left a much more rough, striated surface.
The parallel lines seen on both of Barndog's half dimes could very well be roller marks, but they are more likely to be adjustment marks. It is impossible to tell from a two-dimensional image. Perhaps Barndog can tell us if the parallel lines are in relief (above the surface) or incuse (below the surface) of Miss Liberty's face. If they are in relief, they are more likely to be roller marks, representing gouges or scratches in the surface of the rollers. If they are incuse, they are much more likely to be from adjustment marks, from a file abrading across the surface of the blank planchet.
Notice that these planchet marks, whatever they are, appear only on the points of highest relief, representing the deepest recesses of the dies [the marks in front of Miss Liberty's lips on the top 1833 are from a very different cause]. Any similar roller or adjustment marks which would have been on other areas of the planchet, such as in the fields, would have been compressed and removed by the pressure of striking.
Nice coins, by the way, and although I always admonish collectors never to attribute a coin by looking at just one side, I will take a stab. The top 1833 appears to be an LM-9/V6 (I think I see a faint die crack from *3 to rim). The bottom 1833 appears to be an LM-7/V5, simply because I do not see a die crack from the rim to cap to B in LIBERTY.
<< <i>Should these marks affect the grade of the coin? >>
Alan, I don't know if they "should" or not, but at least in the case of higher grade mint state coins, they can. Even though they are mint-made, they can be seen as a distraction.
It seems more probable that the lines are the result of "damage" to the rolling stock as it enters or exits the drawing press.
If I am wrong, then somebody please explain how pieces of grit stuck to a roller which contacts the bar stock only one per circumference can cause parallel striations. Pits or other types of "point" damage makes sense, but not parallel striations. I appreciate how all these can be "lumped together" as "roller marks" but one "explanation" seems to defy the laws of physics.
Lane
Edited for grammar...
See http://www.doubledimes.com for a free online reference for US twenty-cent pieces
Term to describe the mostly parallel incuse lines seen on some coins after striking. These were originally thought to be lines resulting from debris “scoring” the metal strips before the blanks were cut. However, new research has pointed to the final step of strip preparation, the draw bar. To reduce the strips to proper thickness, the final step was to pass them through the draw bar. It certainly seems logical that debris in the draw bar may cause these lines, if so, then draw-bar marks or lines would be a more appropriate term.
machine. A rolling machine reduced the ingots to the proper thickness for the planchets.
Not quite the required reduction to the exact size, just a bit thick (done in the next step).
The ingots were not put through just once. They were reduced by increments and for silver
this usually required 8 passes (gold 10 passes). Between rollings the metal was annealed
to prevent breakage and making the metal soft enough to pass through. A one foot long
ingot became 6 feet long when done. The operator adjusted the thickness each time,
reducing it in small increments to the desired thickness for the planchet. Occasionally the
rollers would encounter a piece of especially hard metal. This is the culprit for the damage
to the rollers.
This is the drawing bench. After rolling to an approximate thickness it goes to the drawing
bench. Here you see two men each "drawing" a strip of metal through two vertically placed
rollers. These rollers are set for the exact thickness required for each coin. Thinner for
dimes than quarters, etc. The strip is fed in through the rollers after the end has been
hammered down so that it can enter the rollers. Once through there is a set of powerful
pincers that grab the strip. The pincers are attached to a chain underneath that pulls the
strips through the rollers. Thus the strips are finally reduced to the proper thickness for the
planchets of each coin.
From here the stips go to the planchet cutting machine to punch the blanks.
bob
Where did this come from? I've gone back and read all of the posts, and I can't see where anyone said that roller marks were caused by debris on the rollers.
<< <i>"Why would a debris on a roller cause parallel raised striations that run the length of the planchet."
Where did this come from? I've gone back and read all of the posts, and I can't see where anyone said that roller marks were caused by debris on the rollers. >>
Read the link from Mark's earlier post...that is from where it came.
Edited to add...
Here is the excerpt from the web page:
Little Bits of Grit - Each time the metal ingot passes through the rollers, the ingot gets a little thinner, because the rollers are moved a little closer together. When the ingot has been rolled this way enough times, it becomes the proper thickness from which to punch out the coin blanks. In order to cause a thick ingot of metal to get thinner, however, the rollers must exert a great deal of force. If any tiny little piece of stray matter gets onto the ingot or the rollers, (such as little shavings of metal, or dirt or sand,) the incredible pressure from the force exerted by the rollers will cause the foreign matter to carve fine lines or grooves into the sheet of coin metal.
Lane
See http://www.doubledimes.com for a free online reference for US twenty-cent pieces
<< <i>I do not believe US Mint personnel were making adjustment marks on coinage in 1833, thus my conclusion that these are examples of coins with so-called "roller marks" >>
I believe that the Mint was still hand filling down or "adjusting" over weight planchets even up until the civil war (maybe even into the 1880's).
The main reason that they show up less often after 1836 is the advent of the steam press, which usually exerted more striking pressure than the earlier hand operated presses, thus eradicating the evidence.
QN
Go to Early United States Coins - to order the New "Early United States Half Dollar Vol. 1 / 1794-1807" book or the 1st new Bust Quarter book!
planchets, at least in the making of Morgan dollars.
As discussed, planchet strips were reduced in thickness to nearly the required size
by rolling presses, which drew the strips between oppossing rollers under immense
pressure. Occasional softening of the planchet strips by annealing them in wood fired
furnaces and cooling with water was required during this process.
The planchet strips were then taken to the Drawing Benches where the strips were pulled
through an upper & a lower cylinder to bring the planchet thickness to it's final diminsion.
It is at this time, with the addition of tallow to ease this operation, that any foreign matter
remaining on the planchet strips, or the cylinders, such as metal filings, debris, etc. may cause
the grooves in the strips we call "roller marks". Foreign matter would be stuck at the cylinder
temporarily causing a scouring of the metal as it is pulled through the cylinders.
By 1901, with improvements in the power & accuracy of the roller presses and the annealing process, the drawing benches
were no longer used.
R.I.P. Bear