Hi Everyone. I was thinking about this and wondering if a coin blank could miss the upset mill process and be fed into the coining dies. If so, what would the result look like? My guess is the blank would have an over sized diameter and therefor either be rejected in the feeding mechanism or be too large to properly fit into the die set. Any opinions? I am a Mechanical Engineer with experience in punch and die sets so don't be afraid to get technical. As an aside, I put myself through college in the 70's buying and selling US silver coins. When I got my degree, it never occurred to me to apply for a job with the mint. That would have been sweet! Thanks. Joe
i would think it would most likely become either an off-center, a broadstrike either centered or uncentered, or a partial collar strike. the diameter difference would probably be small enough that the feed equipment could handle it, but it probably could not drop down into the coining chamber. Since the anvil die and collar are still working I would think the broadstrike or partial collar strikes would be more likely than the off-center.
I don't believe that the blank is cut larger than the diameter of the actual coin. It's my understanding that the sole purpose of the upsetting mill is to squeeze the blank to partially form the rim so that when it enters the coining chamber, the metal can flow more readily outward from the center of the planchet and up/down to finish the rim. If the upsetting mill was bypassed, there would likely not be enough pressure to completely form the rim. The same would be true if the coin has a reeded edge (third side) and the metal has to flow into the recesses of the collar the full thickness of the upset rim. Chris
From what I always understood, the blanks (T1) were only slightly reduced during the Upset Mill process. The rim is basically for strength and to help reduce wearing out the coin...
The blanks are probably cut to the size of the finished coin and then reduced slightly in the upsetting mill. The coining chamber is the same size as the finished coin. If you try to drop a type I blank into a hole the exact same size you will find that it will almost never go in. This is because if the blank tips any at all, its distance across is now greater than the diameter of the hole and it will jam and not fall in.
