1982 LMC Rim Trench - What Would Cause This?

I have been trying to imagine what might have caused this trench on the rim. My current thinking is focusing on a defective planchet being fed into the upsetting mill. Maybe it was slightly out of round and lacking a small amount of metal volume in the area of the trench. While I don't exactly understand how.

Thanks, coop. That definition of fining really does not fit what is going on with this coin. This coin has a clear trench. There is no evidence even of a fold over Rim Fin in this area of the coin. There is missing metal where there should be a full rim. A Rim Fin at least adds a very small amount of metal to some portion of the rim.

The only explanation I can think of seems to me to point towards the upsetting process and there not being enough metal to complete the rim in that section. That, in turn, points to some kind of planchet irregularity. It is as if the rim was never completely formed in this area. I can visualize the planchet having an elongated hollow tube along this area which causes it to take this shape during the upsetting milling process.

No problem, CM. I am just looking for someone to think this through with me.

Seeing this as a planchet void on the outer edge is as far as I can go in my thinking at this point.

That sounds logical, and looks logical on the coin as well. The counter probably "dug" the trench in the process.

Now that is an interesting possibility. I am trying to think about that. The way I understand it the fin will be a piece of very thin metal on the very outside edge of the coin vertical to the plane of the coin itself. In order to reduce the metal on the rim, some of that metal would have to be pulled off along with some of the metal of the rim itself. It would seem that the metal should come from the very outside of the rim, which did not happen here.

The other possibility, then, would have to be that the fin was folded over the rim in just this affected area (no sign of that anywhere else) and pulled off immediately during the conclusion of the strike. Perhaps there could have been some kind of planchet inclusion (which fell of or was pulled out by the fin) to contribute to that process. The weight of the cent is 3.07g, so that is a more likely possibility, I think, than if it were a zinc based planchet.

It still could be a planchet void, I think - which might be more likely with a copper based cent also.




When I look closely at the form and shape of the trench, it just does not have any of the characteristics of a mark from a counter. Counter marks I have see have also never been right on the edge of the coin, but always inside the edge by at least 5 to 10mm. Also, there is no evidence of a dig or gouge after the strike - no pressure ridge or metal scraps.

tweak - I don't mind you posting in this thread at all. Someone in a private E-mail has suggested to me that the cause of this may never be known - especially since it is not known to have been repeated on the cents, at least. If your quarter appears to be exactly the same thing, then that would be interesting!