What happens with an oversized planchet?

Discussion in 'Error Coins' started by Asher, Jul 25, 2021.

  1. Asher

    Asher Member

    There's the hammer/anvil dies and the collar.

    This whole post makes the assumption that the collar is a bit larger than the planchet to allow metal to flow into a reeded collar and to allow a planchet to easily fit into the collar. Is there any standard difference in diameters?

    Say a planchet is slightly larger than what the coin press is set up for, but still fits into the collar? (The planchet is as large as possible to fit, so no off-centering) What would the struck coin look like? Just a slightly thicker coin?

    One reference I've used, but it's a bit advanced:
    https://coinauctionshelp.com/mintingprocesshistory.html
     
  2. Avatar

    Guest User Guest



    to hide this ad.
  3. yakpoo

    yakpoo Member

    My understanding is that the collar (the 3rd die) is comprised of segments that open to accept a blank then closes in tightly as it readies for the strike. I imagine that if the planchet was larger in diameter, there would be noticeable spikes on the edge where the collar can't quite close together...and a slight broadstrike, but that's just a guess.

    "Particularly of interest were the several references I found to the three-piece, segmented collars used for coining Saint-Gaudens double eagles. Examining the edges of this coin type you will find three raised lines running at right angles to the coin's obverse or reverse. These are the parting lines where the three pieces of the retractable collar met one another at the moment of striking."

    https://www.ngccoin.com/news/article/804/

    [​IMG]

    https://www.coinnews.net/2013/04/17/u-s-mint-at-san-francisco-coining-press-room/
     
    Last edited: Jul 25, 2021
    thomas mozzillo likes this.
  4. Insider

    Insider Talent on loan from...

    Not all collars are segmented.
     
    John Burgess likes this.
  5. Conder101

    Conder101 Numismatist

    What the OP is basically describing is a coin struck on a blank and not a planchet. The blank is the same size or possibly a tiny bit larger than what the finished coin would be. Normally when it would go through the upsetting machine that creates the "proto-rim" the diameter is reduced to slightly LESS than that of the finished coin. This allows the planchet to drop easily into the coining chamber, and then the force of the strike causes it to expand outward and fill the collar.

    In the case of a blank it does NOT fall easily into the chamber. Instead it is forced into the collar by the hammer die. It could go in slightly tipped. it could create an off-center strike, or it may just get pushed in in a centered fashion. But I would expect the rims to be weak on the finished coin because it doesn't have that added thickness around the rim created by the upsetting machine.
     
  6. Asher

    Asher Member

    Thanks for all the good technical stuff. I can’t imagine that the planchet (and I’ve always meant upsetted and any other process that is done prior to striking) is forced into the collar by the hammer die. What puts the planchet in position to be “forced” in position?
     
  7. Conder101

    Conder101 Numismatist

    My knowledge on this mostly comes from the old vertical coining presses, but after the previous coin was struck the anvil die rises forcing the coin out of the collar. Next the feed fingers move forward pushing the struck coin out and placing the next planchet over the face of the anvil die. The die retracts and the planchet falls into the coining chamber. In the case of a blank (Not a planchet, a planchet is smaller than the opening in the collar and drops in easily) the fingers have pretty much centered it over the anvil die but when the die retracts the blank does not just drop into the chamber (because it is basically the same size as the hole.). It may drop in on one side, or drop but be wedged at an angle, or it might even remain perfectly suspended above the chamber with it rim resting on the top edge of the collar. Then the hammer die come down and bam, forces the blank down into the chamber.
     
  8. Asher

    Asher Member

Draft saved Draft deleted

Share This Page