The Australian Numismatic Society
A Paper given at the June
2020 online Conference
A
Study of
Off-Centre Strikes and Coinage Press Die Placement:
Australian Pennies
and Halfpennies by Paul M. Holland
Off-centre strikes occur when the coinage blank or planchet is
struck while not properly seated within the collar of the coining
press. If a significant portion of the
planchet lies outside the collar the coin will only be partially
struck, creating an off-centre error coin. Of special importance to the
present investigation is that off-centre
error coins tend to be bent or ‘cupped’ when the planchet is
squeezed against an inner edge of the collar by the downward force of
the moving upper die. This ‘cupping’
feature clearly reveals the orientation of dies in the coining
press. For example, if an off-centre coin is cupped toward the obverse,
then the obverse die was positioned as
the upper or “hammer” die the coining press at the top and the
reverse die as the lower or “anvil” die. It should be noted, however,
that not all off-centre coins show this
cupping effect clearly enough to reveal the orientation of the
dies in the coining press.
This can provide valuable numismatic information on predecimal
coinage, since the orientation of coinage dies is not otherwise
recorded in mint records. Thus the only
way to ascertain die placement in coinage press it is by the
study of off-centre strikes. Unfortunately, such error coins are
relatively rare (and often expensive) making
comprehesive study of them difficult. I’ve been slowly
accumulating examples of these for more than twenty-five years and with
a number of acquisitions made during my
visit to Australia in 2017, this now allows me to extend my
previous work on pennies[1] to halfpennies, and to provide more
comprehesive results for Perth mint pennies.
Examples of pennies struck off-centre at the Perth and Melbourne
mints, respectively, are shown in Figure 1. These reveal that the
obverse die was positioned in the
coining press as the upper die for the 1945 Perth Mint penny,
while the reverse die was on top for the 1949 Melbourne Mint coin.
Figure 1. Examples off-centre
pennies struck at the Perth and Melbourne mints.
Fortunately, it’s possible to independently confirm this orientation
for Perth mint penny dies based on a radio script from 1945 in Perth
mint records. In the transcript,
Mr HL Moore, the Foreman of Machinery, explains that
The bottom die for the reverse side is a fixture and the obverse or
head die is fixed in the moving head. As the blank is fed on to the
bottom die the moving head comes
down and stamps the piece, which as you see is held by a
surrounding steel collar. So both impressions are given to the coin at
the same time.[2]
The unusual observation of a reversal in die orientation for bronze
pennies between the two mints is clearly highlighted in the survey of
forty off-centre strike pennies in my
reference collection shown in Table 1. Note that in one case I’ve
supplemented these results using an auction photograph for a 1964 Perth
mint penny where the die
orientation was clearly discernable. The most important new
finding in these results is clear evidence that both coining press die
orientations are now clearly observed for
Perth Mint pennies of 1962-1964. More on that later.
Table 1. ‘Cupping’ orientation of off-centre error pennies by date and
mint.
Date
Mint Orientation Number of coins
1941 K.G Perth
Obv 1
1942 Y. Perth
Obv 2
1943 Y. Perth
Obv 1
1944 Y. Perth
Obv 4
1945 Y. Perth
Obv 1
1947 Y. Perth
Obv 1
1950 Y. Perth
Obv 1
1952 A. Perth
Obv 1
1953 A. Perth
Obv 1
1957 Y. Perth
Obv 1
1959 Y. Perth
Obv 1
1960 Y. Perth
Obv 1
1961 Y. Perth
Obv 3
1962 Y. Perth
Obv 1
1962 Y. Perth
Rev 1
1963 Y. Perth
Obv 1
1963 Y. Perth
Rev 1
1964 Y. Perth
Obv 1
1964 Y. Perth
Rev 1*
1947 Melbourne
Rev 1
1948 Melbourne
Rev 2
1949 Melbourne
Rev 3
1950 Melbourne
Rev 3
1951 Melbourne
Rev 1
1952 Melbourne
Rev 1
1964 Melbourne
Rev 5
Obv = Obverse is upper die; Rev = Reverse is upper die; * from auction
image.
Examples of halfpennies struck off-centre at the Perth and Melbourne
mints, respectively, are shown in Figure 2. These reveal that the
obverse die was positioned in the
coining press as the upper die for both the 1963 Perth Mint
halfpenny and 1959 Melbourne Mint coin.
Figure 2. Example off-centre
halfpennies struck at the Perth and Melbourne mints.
A survey of coining press halfpenny die orientation revealed by
seventeen off-centre strikes in my reference collection is presented in
Table 2. This includes results for
some sixteen Perth mint halfpennies from 1945 to 1963, but only a
single 1959 entry for Melbourne. This is perhaps understandable since
after 1944 virtually all halfpenny
production had been transitioned to the Perth mint, with the only
two halfpenny dates struck at Melbourne being 1948 and 1959. The Perth
mint halfpennies examined all
show the obverse to be the upper die, including twelve from the
years 1945-53, together with four from 1961-63.
Table 2. ‘Cupping’ orientation of off-centre error halfpennies by date
and mint (see text).
Date Mint
Orientation Number of coins
1945 Y. Perth
Obv 1
1946 Y. Perth
Obv 1
1947 Y. Perth
Obv 1
1948 Y. Perth
Obv 4
1949 Y. Perth
Obv 2
1951
Perth Obv
2
1953 A. Perth
Obv 1
1961 Y. Perth
Obv 3
1963 Y. Perth
Obv 1
1959 Melbourne
Obv 1
Obv = Obverse is upper die
So why should this information be of numismatic interest? Besides
providing unique information about the orientation of dies in coining
presses, this seems to offer the only
way to explain why ‘strike-doubled dates’ are relatively common
among Melbourne mint pennies, but are not observed on those from the
Perth mint. Such coins have
incorrectly been described over the years as being ‘double
struck’ or having ‘re-cut’, ‘re-entered’ or ‘re-engraved’ dates’. For
example, John Dean lists such Melbourne
mint pennies for 1948, 1950 and 1951 with catalogue numbers
P48A(a), P50A(a), and P51B(a).[3] Foster shows these for
Melbourne mint pennies of 1948, 1949,
1950, 1951 and 1952 in the first edition of his book (P50, P51,
P53, P56, P57).[4] Interestingly, neither author lists any for
Melbourne mint halfpennies or Perth mint
bronze coins. I show examples of such ‘strike doubled dates’ on
Melbourne mint pennies from my reference collection in Figure 3.
Figure 3. Melbourne Mint pennies
with strike-doubled dates.
In fact these are error coins, with no two precisely alike. They are
the result of a process known variously as ‘strike-doubling’,
‘mechanical doubling damage’ or
‘machine-doubling’ that is believed to be caused by
looseness in the die or coining press mechanism. This allows movement
of the die while it is still in close contact with
the newly struck coin. Here, a momentary lateral motion can be
imparted to the loose die allowing it to rebound during this vibration
and drag across the face of the coin
as it withdraws after striking the coin. This can produce the
flat areas of damage that are characteristic of strike or mechanical
doubling. I’ve made precision
measurements of the displacement shown in these flat areas on
Melbourne Mint pennies and my results reveal the largest to be 0.3 mm,
or about 1% of the diameter of
the coin.
Because areas on the coin with the sharpest changes in relief are most
affected, strike-doubling is especially noticeable at the date (a part
of the coin which is almost
always carefully examined by collectors). However other parts of
the design are also affected, for example note clear evidence of
“strike-doubling” at the bottom of the
kangaroo’s tail just above the dates in Figure 3.
Typically only portions of a coin are affected; for example, several
letters of the legend may exhibit strike-doubling but the date will
not, or sometimes only a few of the
date numerals may exhibit doubling. The close resemblance of
coins with strike-doubling to coins made from doubled dies can be a
source of confusion for collectors.
Generally, strike or machine doubling exhibits flat ledge or
shelf-like areas, whereas the features on doubled dies are typically
more rounded and will often show both the
doubling of portions of letters and the ‘splitting’ of serifs
(which are due to hub misalignments when pressing the design into the
die during manufacture).
The results of Table 1 also show that both orientations of obverse and
reverse penny dies in the coining presses at the Perth mint first
appeared sometime during 1962, and
both positions are observed each year from 1962-64. This seems to
coincide with two new coining presses coming into service at Perth in
1962 in addition to the five
already in use.[1] Here, Press #7 began striking pennies on May
30th, followed by Press #6 on July 3rd. Although the reason for both
die orientations is not understood,
it may be that these new coining presses were set up differently.
Previous survey results for some 305 Melbourne mint pennies with
strike-doubled date from 1947-1953 in my reference collection are shown
in Figure 4 as the dark
bars.[1] It should be pointed out that this is simply a raw
count of the number of these coins observed in my collection, and is
not a statistical sampling. Even so, the
results show a pronounced upward trend for the years 1948 to
1952, with a very sharp reduction in 1953, dropping from 89 coins in
1952, to only four in 1953. If a
relative comparison of these results to mintage figures (in
millions, light colored bars) is plotted using the same scale, the
years 1949-1952 show a substantial relative
excess (i.e the problem became worse). The sharp drop in 1953
suggests that strike or mechanical die doubling was probably recognized
as a problem at the Melbourne
mint by late 1952 and that corrective steps were taken. However,
without access to detailed Melbourne mint records for this period,
precisely what occurred is unclear,
although it seems likely that either repairs or maintenance to
the offending coining press (or presses) were made and improvements in
the regular maintenance schedule
were probably instituted.
Figure 4.
Distribution of 305 Melbourne mint pennies with
strike-doubled dates compared to mintage figures (see text).
It should also be pointed out that in 1953 a substantial reduction in
the relief of the reverse die from 1/2 to 3/8 relief or by 25% was
being instituted, and this was the
source of some controversy at the mint.[5] Although in fact, 1953
long 5, different 3 Melbourne pennies with the new lower relief reverse
are rare coins, amounting to
only a few percent of the 1953 pennies struck in Melbourne and
none of these appear in my Figure 4 survey.
In conclusion, the study of off-centre strike coinage errors offers an
unusual approach for extracting numismatic information and may lead to
important new insights. In the
present case, an examination of off-centre penny strikes reveals
differences in the placement of obverse and reverse penny dies in
coining presses at the Perth and
Melbourne mints. This helps explain why pennies with
strike-doubled dates are so common in Melbourne mint pennies compared
to those from the Perth mint. In
extending this study to off-centre strikes of predecimal
halfpennies, no differences in die orientation between the Perth and
Melbourne mints are seen, with the obverse
always being the upper die. This is consistent with no
strike-doubled dates being observed in these coins.
Acknowledgement
The author would like to acknowledge Bob Roberts and Joe Dettling of
M.R. Roberts for their help in obtaining off-centre strike pennies and
halfpennies crucial for this study.
References
1. Holland, Paul M., “Numismatic Information from the Study of Coinage
Errors”, Journal of the Numismatic Association of Australia, 14, 2003,
pages 41-46.
2. Personal Communication from Anthea Harris, Records
Coordinator and Curator, The Perth Mint, of an ABC radio transcript
recorded 22 August 1945 and
broadcast on 12 October 1945 at 9:08pm through 6WF and regional
stations, Perth Mint record PM5717; together with other information
from the Perth Mint
‘Die Account’ book.
3. Dean, John. Australian Coin Varieties Catalogue, 1st edn,
Hawthorn, Melbourne, 1964.
4. Foster, Derek J. Catalogue of Australian Coin Varieties, 1st
edn, Blacktown Auctions, Blacktown, NSW, 1964.
5. Holland, Paul M., “Mystery of the ‘Missing’ Reverse Die Type for the
1953 Perth Mint Penny”, Australasian Coin & Banknote Magazine,
Yearbook
December 2017/January 2018, pages 8-10.
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13th June 2020