object of this test was to reduce the master copy of the Lords 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.
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 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.
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.
result of this experiment was the complete Lords Prayer consisting
of 300 characters engraved on the end of a platinum gold alloy wire within
a circle of .005" in diameter. Two cigarette papers are approximately
.005" thick. (Using the same size letters, the entire Bible of approximately
2,750,000 characters could be engraved within an area of 1/2" X 3/8".
The complete Lords Prayer engraving therefore appears as a very
faint speck on the end of the gold wire when viewed with the naked eye.
The letters are so small in height (about .0002") that they must
necessarily be engraved very shallow. In fact, the depth of each letter
in the metal is only 1/40,000 of an inch. This depth is so slight that
a mere rubbing of a finger over the finished job would be sufficient to
obliterate it entirely or at least to make it unreadable.
lettering requires a magnification of about 175 diameters to read. For
inspection of the lettering during the actual engraving process a smaller
power glass was used for the reason that the cutter operating directly
above the engraving made it necessary to mount the glass at an angle for
observation, and at this angle the field of view was so small that only
one line at a time could be focused.
A 1/10" diameter piece of Sandersons Double Special Steel was
used for the cutter. This is a water-hardening steel of extreme hardness
capable of retaining a very fine point. The cutter was rough-ground to
the approximate shape desired in a standard Gorton universal cutter grinder
using a 35-80 Alundum BM wheel.
When examined under a microscope, the rough-ground cutter showed a series
of flats and irregularities around its circumference. These were removed
by turning up and polishing using a small boxwood wheel about 1"
diameter running at 1,700 R.P.M. this wheel was charged with pumice. During
the polishing operation, the point of the cutter was held very lightly
so as not to burn it.
After polishing the point true, the cutter was placed in a polishing lathe
where it was stoned very lightly with a natural Pike Stone to bring out
the bullet-shaped point and to further sharpen the point. The stone used
was held in a fine spring clip about 3" long, so that at no time
was any stoning process, the point was repeatedly examined under the microscope
in two positions so as to make sure it was true and not oval in shape.
Lords 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.