This week's JR Newsletter starts with a response to Winston
Zack's inquiry from last week.
Dick Johnson wrote:
In answer to Winston's inquiry about sinking a design into a
die and the kind of press used to do this.
Surprise! The press used to sink a device into a die is the
same as one which could be used for striking coins.
The answer is the screw press. A very brief background of
the screw press.. The first such press was developed 1st century BC to
press grapes into wine. In 1506 an Italian engineer developed a screw press to
blank lead sheets to make seals for the pope.
In the mid 1500s screw presses were in use in European
mints. In 1652 John Hull obtains a screw press to strike his Pine Tree
shillings in America.
A collar and ejection mechanism is added to the screw press at the Bologna Mint
by Francesco Camrlli in 1786.
Matthew Boulton, father of the private mint, and his partner
James Watt add Watt's steam engine to their screw press enabling them to strike
coins in quantity (instead of hand feeding).
In 1792 David Rittenhouse obtains a screw press for the
Philadelphia Mint, and Adam Eckfelt builds additional screw presses biased on
that first one. In 1851 the London Mint adapts a screw press just for
their hubbing needs. In America
the Philadelphia Mint acquires a screw press specially for hubbing in 1892.
Screw presses can be found in machine shops today
for use in moderate pressing work.
I mentioned hubbing. The ancients knew of hubbing for use of
copying dies as early as circa 530 BC. Because iron can be treated (by
heating and rapid cooling) it can be hardened or softened at
will. A hub would be hardened and pressed into a soften die blank by
use of a screw press.
Now what the engravers did at the Philadelphia Mint was to
engrave the device image only in the correct size. Some engravers like to work
in the positive, having the image in front of the constantly, or carve the
image negative. Hubbing changes polarity. You need a positive hub to make a
negative die.
The device only was in this hub. All lettering, stars and
dentiles forming the border were added individually by punches. Tap a punch (of
hardened steel) into a soft iron die blank and it forms the image at the end of
the punch.
This diesinking is tricky work as the position of the punch
is critical. It must be in line (same base line) with other letters;. the
distance from the proceeding letter is critical, as well as the rotation of the
punch. Finally how hard the punch is tapped results how deep it sinks into the
die (to become a raised letter when struck). This depth must be uniform for all
lettering.
This method continued throughout the 19th century, at
the Philadelphia Mint even though it had a die-engraving pantograph (the
Contimin) in 1836, replaced by the Hill reducer in 1857. They obtained models
from sculptors, made patterns from these first in iron, later in copper. The
Mint used these machines for the device image only, preferring to add
everything else by punches.
It was not until 1920 and de Francisci's Peace Dollar, did
the Mint cut the entire image -- device and all -- on their Janvier
pantograph. Victor Janvier developed his machine in France
beginning in 1892 and pattend in 1999. Medallic Art Company imported the first
Janvier to America
in 1902 and sold one to the Philadelphia Mint in 1905.
Were it not for the Janvier die-engraving pantograph we
might still be engraving dies by hand.
Winston can find pictures of screw presses on Google
as well as Janvier pantographs.
Dick Johnson
Author, Editor, Senior Consultant
Cofounder - Signature Art Medals
Corporate Historian - Medallic Art Company
------
And speaking of Winston Zack…
Winston wrote:
Congrats Bob Feldman on being the first reported person to
reach 123/123 known capped bust dime die marriages. I'm sure there will be many
more congrats coming your way. Certainly your accomplishment underscores the
difficulty to reach such a goal. On average you added 2.5 new die marriages
every month!
We all look forward to seeing you upgrading your set in the
future. Not to mention, at the rate you acquired your capped bust set, you
should be able to acquire all 30 draped bust dime die marriages by this time
next year! And if you can do that primarily from eBay that will be all that
more impressive!
Best,
Winston
------
David Quint also wrote with his congratulations for Bob
Feldman and other comments:
An excellent JR Newsletter last week IMHO. The Finkelstein
article on early mint operations is excellent, I can't wait for the future
installments. The best thing I have on early mint operations is the Taxay book
on the US Mint and Coinage, which is quite detailed but hasn't been update for
50 years. The book does go into some detail as to how working dies were punched
by "gravers" which Winston Zack will find helpful in answering his
questions (the letters and stars were punched by hand, not machine).
I am blown away that Bob Feldman has built a complete set of
capped bust dimes (including the R-8 1827 JR-14), and that he did it in only 4
years. In the last dime census, we had 8 collections of 122 coins, and there
has never been a set of all 123 (Bob's capped dime collection was not even
included in the last census due to a communications issue). This is really
quite a feat and an event in the world of capped bust dimes. Congratulations to
Bob!
I've attached a recent study I did of the 1798 JR-4 obverse
die states. This variety exhibits a spectacular series of prominent die cracks
that traverse much of the right obverse field (the JR-4 was the only use of
this obverse die). I found all of the pics on the Heritage site.
David Quint
Editor: David's study of 1798 JR-4 obverse die states is linked here: http://www.docstoc.com/docs/173893104/1798%20JR-4%20Obverse%20Die%20State%20Progression.pdf
------
Finally, Peter Mosiondz, Jr. wrote with some book offerings:
The Early Coins of America,
Sylvester Crosby. 1983 Quarterman reprint. HB. DJ protected in Brodart Mylar®.
New. $25.00
United States Copper Cents 1816-1857, Howard R. Newcomb. 284
pp. 11 plates. HB. DJ protected in Mylar®. New. $25.00
Illegal Tender: Gold, Greed and the Mystery of the Lost 1933
Double Eagle, David Tripp. SB. New. $15.00
Million Dollar Nickels: Mysteries of the Illicit 1913 Liberty
Head Nickels Revealed, Paul Montgomery, Mark Borckardt and Ray Knight. HB. DJ
protected in Mylar®. New. $20.00
Add $3.00 Media Mail Postage
Peter Mosiondz, Jr.
JRCS #867
26 Cameron Circle
Laurel Springs,
NJ 08021-4861
856-627-6865
choochoopete(at)comcast.net
No comments:
Post a Comment