Why Is The Rim Of an Off Center Strike Nickel Extra Thick?
 

I posted an item earlier today about finding an off center strike on
the obverse side of a Jefferson Nickel. I have had the opportunity to
measure the thickness of the edge of the coin from obverse side to
reverse side against a normal strike, and as I could see with the
naked eye when I first found the coin, when you look at this coin from
edge-on compared with a normal strike coin placed next to it, it is
thicker, even with the naked eye. I don't know what tolerances the
mint deals with in edge thickness, but here is what I found:

Using a pair of calipers and measuring the thickness of the edge from
obverse to reverse at 12:00 (top of Tom's head being 12:00), 3:00,
6:00 and 9:00... (A = off center coin, B = normal coin)

12:00 A = .078" B = .075" (thickest side)
03:00 A = .0785" B = .078"
06:00 A = .079" B = .078"
09:00 A = .078" B = .077"

For those of you who delve in this kind of thing, why has more metal
flowed into the rim, making the coin thicker at the rim? This strike
is not far enough off center to have chopped off any of the devices on
the coin, but is great enough that it is very obvious to the naked
eye. The edge with the narrowest wire rim is sharp enough to cut your
finger. Just looking for more education on the intricasies of this
great past time.

Subject: Why Is The Rim Of an Off Center Strike Nickel Extra Thick?
From: (MIckey)
Date: 7/24/03 11:57 PM Central Daylight Time
Message-id:

I posted an item earlier today about finding an off center strike on
the obverse side of a Jefferson Nickel. I have had the opportunity to
measure the thickness of the edge of the coin from obverse side to
reverse side against a normal strike, and as I could see with the
naked eye when I first found the coin, when you look at this coin from
edge-on compared with a normal strike coin placed next to it, it is
thicker, even with the naked eye. I don't know what tolerances the
mint deals with in edge thickness, but here is what I found:

Using a pair of calipers and measuring the thickness of the edge from
obverse to reverse at 12:00 (top of Tom's head being 12:00), 3:00,
6:00 and 9:00... (A = off center coin, B = normal coin)

12:00 A = .078" B = .075" (thickest side)
03:00 A = .0785" B = .078"
06:00 A = .079" B = .078"
09:00 A = .078" B = .077"

For those of you who delve in this kind of thing, why has more metal
flowed into the rim, making the coin thicker at the rim? This strike
is not far enough off center to have chopped off any of the devices on
the coin, but is great enough that it is very obvious to the naked
eye. The edge with the narrowest wire rim is sharp enough to cut your
finger. Just looking for more education on the intricasies of this
great past time.

It sounds like you've got a minor horizontal misalignment of the obverse
(hammer) die. Sometimes the edge is thicker on the side the die has moved away
from. That's probably because this has opened up a wider gap between die neck
and collar, and metal flows toward the path of least resistance.

Horizontal misalignments are sometimes associated with marked finning of the
rim, which will create a very thick edge. This may be due to a slight degree
of die tilt, which will increase the effective striking pressure on the side
that the die is tilted down toward.

In either case, if the edge is markedly thickened, you should see the design
rim (where the metal has flowed into the rim gutter of the die) lying just
inside a false rim that is in actuality a pressure ridge forced up between the
die neck and the collar.


Host: Error Coin Information Exchange (Yahoo:Groups); CONECA #2969.
Opinions expressed here are strictly my own.

Thanks for the detailed info Mike. I will check it out tonight and
post back. I don't have the coin with me at this time, but I believe I
was seeing what you are describing here.


In either case, if the edge is markedly thickened, you should see the design
rim (where the metal has flowed into the rim gutter of the die) lying just
inside a false rim that is in actuality a pressure ridge forced up between the
die neck and the collar.


Host: Error Coin Information Exchange (Yahoo:Groups); CONECA #2969.
Opinions expressed here are strictly my own.