IMPROVEMENTS IN SHARPENING FILES AND OTHER TOOLS
Year: 1877

page_text: LETTERS PATENT to Alfred Vincent Newton, of the Office for Patents, 66,
Chancery Lane, in the County of Middlesex, Mechanical Draughtsman, for the
Invention of "IMPROVEMENTS IN SHARPENING FILES AND OTHER TOOLS." A
communication from abroad by Benjamin Chew Tilghman, of Philadelphia, in
the State of Pennsylvania, United States of America.
Sealed the 26th March 1878, and dated the 3rd December 1877.
PROVISIONAL SPECIFICATION left by the said Alfred Vincent Newton at
the Office of the Commissioners of Patents on the 3rd December 1877.
ALFRED VINCENT NEWTON of the Office for Patents 66 Chancery Lane in the
County of Middlesex, Mechanical Draughtsman. "IMPROVEMENTS IN SHARPENING
FILES AND OTHER TOOLS." [A communication from abroad by Benjamin Chew
Tilghman of Philadelphia in the State of Pennsylvania United States of
America.]
The difficulty of sharpening files, rasps, and similar tools operating by means of
a great number of small teeth edges or points is well known.
Now the object of the present Invention is to facilitate this operation, and to
this end the cutting power of a blast of sand is employed in lieu of the means
hitherto adopted.
Supposing it to be desired to sharpen a file or rasp, a current of sand moving at a
high velocity is directed against the slanting or handle side of the teeth of the file
or rasp, so as to grind away some of the metal from that side and produce a sharp
edge or point.
The direction of the current should be from the handle and towards the point of
the file, but the angle is not confined within narrow limits, about ten degrees from
the plane of the file face gives good results.
If the current is directed nearly perpendicularly to the plane of the file face, the
teeth are worn away with but little or no sharpening effect, and if the direction is

page_text: from the point towards the handle end of the file, the effect will be to dull the
teeth.
The smaller teeth to be sharpened, the finer should be the grain of the sand used.
The time required will vary according to the power of the sand blast employed
and the quantity of metal to be ground away.
The sharpening process may be repeated many times until the teeth are nearly
worn away.
When the teeth of a file are choked with metal, they may be cleaned by directing
the sand blast lengthways of the cuts, and downwards, so as to rake between the
teeth, and the sharpening procoss should be afterwards applied.
Emery or other cutting substances may be used instead of sand.
New files are made sharper and machine cut files are improved by this
process.
Saws may be sharpened in the same way as files; also milling tools or circular
files or cutters, reamers, metallic mills, and generally cutting, grinding, or abrading
machines or tools operating by teeth or points.
Edge tools or cutting instruments, particularly those of irregular shapes and
difficult to grind by ordinary methods, may be sharpened by a sand blast directed
from the back towards the edge at a suitable angle.
The methods of producing the sand blast are now well known, and are described
in the Letters Patent granted to me and numbered respectively 2147 and 2900 of
the year 1870.
Good
results have been obtained with an apparatus working with steam of
about sixty pounds per square inch pressure and sand which has passed through
a sieve of forty-five wires to an inch.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Vincent Newton in the Great Seal Patent Office on the 3rd
June 1878.
ALFRED VINCENT NEWTON of the Office for Patents 66 Chancery Lane in the
County of Middlesex, Mechanical Draughtsman. "IMPROVEMENTS IN SHARPENING
FILES AND OTHER TOOLS." Being a communication to me from abroad by Benjamin
Chew Tilghman of Philadelphia in the State of Pennsylvania, United States of
America.
The sharpening of files, rasps, and similar tools furnished with a great number of
cutting teeth, edges, or points has hitherto presented considerable difficulties.
Now the chief object of the present Invention is to avoid these difficulties, and
to this end the cutting property of a blast of sand or its equivalent is rendered
available by directing the same against the slanting or handle side of the teeth of
the file or rusp. The effect of this will be to grind away some of the metal from
the back of the teeth and produce a sharp edge or point.
It is essential to the obtaining of the proper effect that the direction of the current
should be from the handle end towards the point of the file, but the angle is not
confined within narrow limits; about ten degrees from the plane of the file face gives
good results.
If the current is directed nearly perpendicularly to the plane of the file face, the
teeth are worn away with but little or no sharpening effect, and if the direction is
from the point towards the handle end of the file, the effect will be to dull the
teeth.
The smaller the teeth to be sharpened, the finer should be the grain of the
cutting material used.
The rate of the operation will vary according to the power of the sand blast
employed and the quantity of metal to be removed.
The sharpening process may be repeated many times until the teeth are nearly
worn away.
When the teeth of a file are choked with metal, they may be cleaned by directing
the sand blast lengthwise of the cuts and downwards so as to rake between the
teeth, and the sharpening process should be afterwards applied.
Emery or other cutting substances may be used instead of sand.
New hand cut files are made sharper, and machine cut files are improved by
submitting them to this process-This appears to be due to the fact that new teeth
have a curl or burr, which is apt to break off in use, leaving the points jagged. By
submitting the new files to the blast, the burr or curl is ground away, and the points
are converted into something like a chisel-shaped cutting edge.
In addition to files and rasps, it is proposed to sharpen, by the aid of the sand blast,
saws, milling tools, circular files or cutters, reamers, and metallic mills, the same
being presented to the action of the blast in such manner that the back of the
cutting edges or teeth will be acted upon by the grit, as explained with reference
to the flat files.
Edge tools or cutting instruments may be sharpened by a sand blast directed
from the back towards the edge at a suitable angle. It should however be stated
that it is not intended to apply the Invention to such edge tools as may now
be readily sharpened by means of a grindstone or emery wheel. In the case however
of cutting edges of irregular shapes, and which it is difficult to sharpen by a rotating
grinding surface, the present Invention may be beneficially applied, the blast being
directed as before described, and the tool being manipulated so as to present the
back thereof always to the direct action of the blast at a suitable angle.-'
The methods of producing the sand blast are now well known, and are described
in the Patents granted to me and numbered respectively 2147 and 2900 of the year
One thousand eight hundred and seventy.

page_text: Good results have been obtained with an apparatus working with steam of about
sixty pounds per square inch pressure and sand which has passed through a seive
of forty-five wires to an inch.
In carrying out this Invention a blast pipe similar to that shown and described
in the Specification of my Patent before mentioned, dated August First One 5
thousand eight hundred and seventy, is employed, the same being supplied with
steam, at a pressure of about sixty pounds per square inch, through a valve cock
which is capable of being opened suddenly to its full extent by means of a treadle
operated by the workman's foot.
The flexible tube connecting the "sand pipe" with the "sand box" is arranged
so as to be easily put on and off the sand pipe to allow of the apparatus being
heated by the steam before commencing work, as otherwise a condensation of
steam would take place, and the sand, by becoming wetted, would clog the flexible
tube.-
The blast pipe is fixed so as to point downward at about eight or ten degrees
from the horizontal.
In starting work with this apparatus, the workman first removes the flexible
tube from the sand pipe, and then opens the valve and lets steam blow through.
Some steam and condensed water generally blow back through the sand pipe, but
in a few seconds a suction of air is established in this pipe. He then slips the
flexible tube on to the sand pipe, so that the sand is sucked in and driven by the
steam through the nozzle pipe. The tang of the file having previously been stuck
into a long handle (a piece of 3/8 inch gas pipe, about three feet long is convenient),
the workman holds the file in a horizontal position close to the end of the nozzle
pipe, and moves it about, so that all parts are subjected to the action of the projected
sand, which strikes it at an angle of about eight or ten degrees from the plane of the
file face. By feeding the teeth, he can judge when they have been sufficiently
sharpened.
Large coarse files, with very dull teeth, may take several minutes to sharpen
each side, while a few seconds may be enough for small files with fine teeth.
To avoid nuisance from the escaping steam and sand, it has been found con-
venient to place the blast pipe opposite a hole about six inches square in the side of
a closet or small chamber open at top to the outer atmosphere, so that the steam and
sand are blown into it, and the steam escapes from its top, while the sand settles to
the bottom.-
When a very smooth and keen edge to the teeth is desired, the grain of the
cutting material should be very small and uniform, and may be even as fine as
the flour emery of commerce.
It is preferred to prepare this grit by the known process of washing and settling,
and to use it in the sand blast apparatus while still mixed with water in the state
of fluid mud.-
It should be kept well mixed and thin enough to flow by the suction through the
sand pipe, the operation in other respects being the same as with dry sand.
An incidental advantage of using the grit in this state is, that the fluid mud,
after acting on the file, may be re-used without further treatment.-It is only
necessary to collect it into a receiver, whence it may be sucked up into the sand
pipe, and thus used again and again until its cutting power has become materially
diminished.
In sharpening the teeth of circular files, rotary cutters, or milling tools, the sand
blast is directed against the back or slanting side of the teeth at an acute angle, so
as to grind away some of the metal from this side in a manner analogous to that
described for flat files.
Having now set forth the nature of the Invention of "Improvements in
Sharpening Files and other Tools,' as communicated to me from abroad, and
explained the manner of carrying the same into effect, I wish it to be understood
that under the above in part recited Letters Patent I claim-The application of a

page_text: blast of sand or other cutting material (directed at a suitable angle) to the sharpening
of files and other tools, substantially as above described.
In witness whereof 1 the said Alfred Vincent Newton have hereunto set my
hand and seal the Third day of June in the year of our Lord One
thousand eight hundred and seventy-eight.