1980 Penny - Double Denticles...?

That is one crazy denticle effect on the rim of that penny, wert. I haven't seen anything like that before. Is the rim raised the full height all along where the denticle design is on it? How would any design get up there without compressing the rim? Hmm...

I've presented the same coin on Numicanada and after some discussion, Castor indicated that it depend on the blank being off-centered in the chamber and a loss of piston pressure on the press. Here is an illustration, in French, to help understand why on some coins you may have denticles on the rim.



The first picture shows the chamber. I've exaggerated the curvature of the working dies to understand the flow of metal of the blank.

The second image represents the process which is similar to rolling pie dough, metal flowing to the extremities. It helps that the working dies are convex.

The third image shows the contact points between the blank's rim and edge of working dies where the denticles are located.

The fourth image is a magnification of the contact point between the working die and the blank's rim. If there is a loss of pressure, metal flow will not be complete and the denticles may appear to be longer or a doubling effect on the rim as found on your coin.

Hope this helps

So what about the collar (the third die)? If there is a loss of pressure at the collar, would you not see early elements or evidence of a broadstruck coin?