The Numismatic Bibliomania Society

PREV ARTICLE       NEXT ARTICLE       FULL ISSUE       PREV FULL ISSUE      

V14 2011 INDEX       E-SYLUM ARCHIVE

The E-Sylum: Volume 14, Number 9, February 27, 2011, Article 13

ENGRAVING ON THE POINT OF A PIN

Dick Johnson submitted this note on an amazing promotional item produced by the Groton Engraving Machine Corporation. -Editor

Point of Pin logo We have often seen the Lord's Prayer engraved on such exonumia items as elongated cents and religious tokens. But an experiment in 1935 by an engraving machine company proved their machine could reduce that lettering on point of a pin! Notice I said the point of a pin -- not the head!

The Groton Engraving Machine Corporation accomplished that feat of miniaturization in 1935. It was written about in an article published 1975 in the second issue of the Engravers Journal. They pulled up that classic article this week and put it on the internet.

To read the mammoth effort in Lilliputian activity click on: www.engraversjournal.com/article.php/14/index.html

Here are some excerpts from the article. -Editor

In 1935 it was decided by the Groton Machine Corporation to attempt a dramatic demonstration of the extreme accuracy built into Groton machines which could be understood and appreciated by the non-technical as well as the technical mind. It is true that the 300 characters which make up the Lordís Prayer had been printed in characters so small that a magnifying glass was necessary in order to read them; they had been cut on a single slug of type and had also been engraved by hand on the head of a pin. But such work had never been successfully done by machine.

Below is their account of their attempt to do this same engraving on the point of a pin. The head of an average pin is approximately 100 thousandths of an inch (.100" or 1/10") in diameter. The point is approximately 5 thousandths of an inch in diameter (.005") or about twice the thickness of a human hair or one sheet of cigarette paper. This article tells the story of how this was done.

The first step was to engrave the Lordís Prayer in the correct design to fit into a circle and of a size which would be suitable for the proper reduction. This was done with the aid of standard Groton copy type. The resultant master or pattern was a 2" circle in which the Lordís Prayer had been engraved.

Then a Groton pantograph was taken from the production line and a few adjustments were made such as disassembling the machine and checking all ball bearings for size and roundness.

The object of this test was to reduce the master copy of the Lordís Prayer to as small an area as possible and still have it remain legible under a magnifier. The machine was set to reduce the original copy 400 times.

Pantograph Lord's Prayer on Point of Pin

The engraving operation was performed by the very point of the cutter and difficulty was experienced in keeping an edge on the point until after numerous experiments, when a comparatively blunt bullet-shaped point was adopted. The next problem was that of polishing the surface to be engraved smooth and flat to within one hundred-thousandth of an inch. Many materials were used Ė different grades of rough, face powder, diamond-tine, etc., but finally it was found that polishing with a fine kid leather produced the finest surface. The kid seemed to have just enough dust embedded in it for proper polishing action.

The pantograph machine had to be insulated against vibrations set up in the shop floor. Although the machine was mounted on the concrete ground floor of their plant with wood block laid on top, the vibrations imparted from machines 100 feet away were sufficient to distort the engraving sufficiently to make it illegible. It was therefore necessary to use four rubber cushions 3" thick beneath the machine in order to eliminate this vibration.

The result of this experiment was the complete Lordís Prayer consisting of 300 characters engraved on the end of a platinum gold alloy wire within a circle of .005" in diameter.

The Lordís Prayer engraving described in this article is a permanent exhibit at the Lars Machine Inc. plant, and has been viewed by thousands of visitors from all parts of the world.

FOR INTERMEDIATE TO ADVANCED COLLECTORS.    .    .    .

The 2nd edition of the Guide Book of United States Coins, Professional Edition, is available now. Its richly detailed content serves the specialist, professional coin dealer, market wonk, and numismatic researcher. 384 pages, spiralbound, full color, $29.95. Order your copy at www.WhitmanBooks.com , or call 1-800-546-2995.


Wayne Homren, Editor

Google
 
NBS (coinbooks.org) Web

The Numismatic Bibliomania Society is a non-profit organization promoting numismatic literature. See our web site at coinbooks.org.

To submit items for publication in The E-Sylum, write to the Editor at this address: whomren@gmail.com

To subscribe go to: https://my.binhost.com/lists/listinfo/esylum

PREV ARTICLE       NEXT ARTICLE       FULL ISSUE       PREV FULL ISSUE      

V14 2011 INDEX       E-SYLUM ARCHIVE

Copyright © 1998 - 2012 The Numismatic Bibliomania Society (NBS)
All Rights Reserved.

NBS Home Page
Contact the NBS webmaster
coin