How do they put the reeded edge on coins?

ksteelheader

Just curious! I can't recall ever reading about it......Ken

byergo

It made it obvious if someone tried to shave precious metals from the rim.

nwcs

Well, there are 2 steps to producing the edge. The first is when the blank goes through the upset mill. This process squeezes the blank a little to produce a rim. When the planchet enters the coining press, it is slid over an anvil die. The planchet sits on it. Around the planchet is a collar that contains the design (reeded in this case) that will be on the third side. The hammer die then strikes down on the planchet and anvil die and heats up the coin surface, which flows into all the available voids which produces the obverse, reverse, and edge.

tporreca

Latest issue of Coin World speaks to this, pp 52 on the 6/16 issue.

Lakesammman

As NWCS outlined, it's the "third" die.

BillJones

U.S. coins since 1836 have had the reeded edge placed upon them when they were struck. The reeding is in the collar.

Early U.S. (half dime, dime quarter and all gold pieces) had the reeding added though a separate operation. The planchets were run though a milling machine that placed the reeding on the edge before the coins were struck. The same type of machine, which had the markings on two large strips, was used to place the lettering on the edge for half dollars and silver dollars.

cladking

Planchets are punched from strip, but these have to be "upset" before they are coined.
Upsetting is rolling the planchet edgewise between two heavy rollers which are too close
together for it to fit. This reduces the diameter a little and pushes up extra metal along
the edge which will form the rim and allow the reeding to fully form. Without the rim the
coins would not stack properly. The reeding itself is formed by a devise which retains the
metal in the proper diameter during strike.

Planchets are type 1's before being upset and are then type 2's.