IMPROVEMENTS IN THE MODE OF EMPLOYING THE SAND BLAST AND IN THE APPARATUS THEREFOR, PARTICU- LARLY APPLICABLE TO SHARPENING FILES AND OTHER TOOLS, AND TO CUTTING, CLEANING. AND FROSTING METALLIC AND OTHER Surfaces.”
Year: 1879

page_text: LETTERS PATENT to Benjamin Chew Tilghman, of Gray's Inn Road, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN THE MODE
OF EMPLOYING THE SAND BLAST AND IN THE APPARATUS THEREFOR, PARTICU-
LARLY APPLICABLE TO SHARPENING FILES AND OTHER TOOLS, AND TO CUTTING,
CLEANING. AND FROSTING METALLIC AND OTHER Surfaces.”
PROVISIONAL SPECIFICATION left by the said Benjamin Chew Tilghman
at the Office of the Commissioners of Patents on the 22nd July 1879.
BENJAMIN CHEW TILGHMAN, of Gray's Inn Road, in the County of Middlesex.
"IMPROVEMENTS IN THE MODE OF EMPLOYING THE SAND BLAST AND IN THE
APPARATUS THEREFOR, PARTICULARLY APPLICABLE TO SHARPENING FILES AND
OTHER TOOLS, AND TO CUTTING, CLEANING, AND FROSTING METALLIC AND OTHER
SURFACES."
Hitherto there has been a difficulty in applying the sand blast to articles so as to
operate in a uniform manner over their entire surface or on several sides.
Either special and complicated machinery has been required to move or rotate
the article or the sand blast pipe or else the operation has required to be repeated
on the different sides. The difficulties have been still greater where it has been
desired to operate in a uniform manner upon great numbers of small articles of
irregular shapes.
The object of the present Invention is to obviate these inconveniences and to
obtain a uniform action of the sand blast in a more simple and economical manner.
In practicing the Invention of sharpening files by the sand blast, as described in
Letters Patent granted to A. V. Newton, 3rd December 1877, No. 4575, as a
communication from me, I have found that the action upon the file was apt to be
not uniform over its surface but to cause an injurious hollowness or concavity.
I have found that this was due to the fact that the blast pipe apparatus used as
described in said Letters Patent produced a round stream of sand, and that in order.
to make it operate over the whole width of the file the latter required to be moved
laterally as well as as lengthways under the blast.

page_text: The improvement is to use a wide and flat sand blast, wide in the direction of
_the_width_of_the_file and flat or thin in the direction of its length, so as to operate
uniformly over the whole width of the file at the same time-and-thus-to-dispense.
with the lateral-motion-
In order to operate_upon_two_adjacent sides of flat or square file simultaneously,
_I-propose to make the flat sand blast considerably wider than the file treated and
to arrange it at an angle sideways to the longitudinal axis of the file, while it is
-also-at-an-angle-to-the-plane-of-the-teeth..
By using two such wide sand blasts arranged so that the upper one inclines
downward and also to one side, while the lower one inclines upward and to the
otherside, and causing the file to be moved horizontally lengthways between them,
all four sides of a file can be sharpened simultaneously.
It is desirable that the workman should have some means of knowing at each
instant of the operation the effect produced on the file and the condition of every
part of its surface, and for this purpose I propose to use a bar of metal (generally
gun metal) as a support upon which the workman keeps the file pressed as it is
moved back and forth under the blast. At first, when the file is dull, it slips
easily over this metal, but as the sharpening progresses the workman perceives that
it bites more and more, and can thus test both sides and every part.
The nozzle tube in which the sand becomes mixed with the steam is the part of
the apparatus which is most exposed to wear and should be of cheap construction
and easily replacable. White cast iron is the best material but it is difficult to cast
a round tube with a very thin core. I therefore propose to make the nozzle tube
of two or more separate pieces, which are held together and in place by a clamp.
In constructing the wide and flat blast pipes to operate with steam and a
mixture of sand and water or fluid mud, I have sometimes introduced the
steam by one or more wide and thin apertures and the fluid mud by another
parallel aperture, but it is an improvement to introduce the steam by a number of
holes placed in rows, with intervals between them to admit the fluid mud. The
mud is introduced from an aperture on one side and is drawn between and around
the steam jets issuing from the holes, and is blown by them into the nozzle tube,
which has a wide and flat aperture or cross section corresponding to the size and
number of the steam holes.
In order that the supply of fluid mud may be of uniform thickness the vessel
containing it is made in the shape of a cone standing on its point, and the mud is
drawn from its bottom. I propose to apply the wide and flat blast pipes supplied
with steam and fluid mud to the cutting, cleaning, and frosting of metallic and
other surfaces. By having one or more such blast pipes to cover the entire width
of the surface treated the action is more uniform and a complicated lateral motion
is dispensed with. Also in a wide and thin sand blast there is less interference
between the central and the outer portions of the blast.
In operating with steam and fluid mud in the round blast pipes, referred to in
the Letters Patent above recited, I propose to introduce the mud in the same way
as herein described for the wide and flat blast pipes, that is, from an outside
aperture, so that it is drawn into and around the steam jet which issues from a
central pipe or hole. I find that this is preferable to introducing the mud from the
central pipe and the steam on the outside.
When it is desired to operate to a uniform degree upon a great number of small
articles there has been a difficulty in holding and turning them under the blast so
as to ensure that all parts shall be equally acted on, particularly if they are of
irregular shape.
For this purpose I propose to turn the sand blast upwards into the furnel
shaped bottom of a high vessel, so arranged that the articles slide down the funnel
by gravity into the blast, which immediately throws them upwards, where they
again fall upon the funnel and slide down into the blast, and are thus kept by it in
circulation and rotation with exposure of all parts to the action.

page_text: The height and shape of the vessel and the force of the sand blast are propor-
tioned to each other and to the weight and surface of the articles treated so that
a proper circulation may be maintained.
When the articles are very light, metallic pens for example, I propose to use a
current of air (produced preferably by a partial vacuum) to propel the sand; and to
avoid breakage when the articles are brittle elastic linings are provided at the
places where the articles would strike with velocity.
A tube, open at both ends, may be arranged in the vessel so as to receive the
ascending sand blast and the articles carried up with it, and to separate them from
the space where the articles are falling back towards the blast and thus facilitate
the circulation.
Suitable sieves are provided to retain the articles while allowing the spent steam
or air and sand to escape.

page_text: ESPECIFICATION-in-pursuance-of-the conditions of the Letters Patent filed by
the-said-Benjamin-Chew-Tilghman-in-the Great Seal Patent Office on the
-22nd-January-1880.-
BENJAMIN CHEW TILGHMAN, of Gray's Inn Road, in the County of Middlesex.
"IMPROVEMENTS IN THE MODE OF EMPLOYING THE SAND BLAST AND IN THE
APPARATUS THEREFOR, PARTICULARLY APPLICABLE TO SHARPENING FILES AND
OTHER TOOLS,-AND-TO-CUTTING, CLEANING, AND FROSTING METALLIC AND OTHER
SURFACES."
Hitherto there has been a difficulty in applying the sand blast to articles so as to
operate in an uniform manner over their entire surface or on several sides.
Either special and complicated machinery has been required to move or rotate the
article or the sand blast pipe, or else the operation has required to be repeated on
the different sides. The difficulties have been still greater when it has been desired
to operate in an uniform manner upon great numbers of small articles of irregular
shapes. The object of the present Invention is to obviate these inconveniences, and
to obtain an uniform action of the sand blast in a more simple and economical
manner than heretofore. In practising the Invention of shapening files by the sand
blast as described in the Letters Patent granted to Alfred Vincent Newton, Third
December, One thousand eight hundred and seventy seven, No. 4575, as a communi-
cation from me, I have found that the action upon the file was apt not to be
uniform over its surface but to cause an injurious hollowness or concavity. I have
found that this was due to the fact that the blast pipe apparatus used as described
in said Letters Patent produced a round stream of sand and that in order to make
it operate over the whole width of the file the latter required to be moved laterally
as well as lengthwise under the blast. The improvement is to use a wide and flat
sand blast, wide in the direction of the width of the file, and flat or thin in the
direction of its length, so as to operate uniformly over the whole width of the file
at the same time, and thus to render unnecessary the lateral motion of the file.
In order to operate upon two adjacent sides of a flat or square file simultaneously,
I propose to use a flat sand blast of a width exceeding the width of the file to be
treated, and to arrange such flat blast diagonally to the longitudinal axis of the file,
while it is also at an angle to the plane of its teeth.
By using two such wide sand blasts arranged so that the upper one inclines
downwards and also to one side, while the lower one inclines upwards and to the
other side, and causing the file to be moved horizontally lengthwise between them,
all four sides of a file can be sharpened simultaneously.
The nozzle tube in which the sand becomes mixed with the steam is the part of
the apparatus which is most exposed to wear, and should be of cheap construction
and easily replaceable. White cast iron is the best material, but it is difficult to
cast a sound tube with a very thin core.
I therefore propose to make the nozzle tube of two or more separate pieces which
are held together and in place by a clamp.
In constructing the wide and flat blast pipes to operate with steam and a mixture
of sand and water or fluid mud, I have sometimes introduced the steam by one or
more wide and thin apertures, and the fluid mud by another parallel aperture, but
it is an improvement to introduce the steam by a number of holes placed in a row
with intervals between them to admit the fluid mud.
The mud is introduced from an aperture on one side and is drawn between and
around the steam jets issuing from the holes, and is blown by them into the nozzle
tube which has a wide and flat aperture or cross section corresponding to the size
and number of the steam holes.
I propose to apply the wide and flat blast pipes supplied with steam and fluid
mud to the cutting, cleaning, and frosting of metallic and other surfaces.

page_text: By having one or more such blast pipes to cover the entire width of the surface
treated, the action is more uniform and a complicated lateral motion is dispensed
with. Also in .a wide and thin sand blast, there is more uniformity between the
central and outer portions of the blast. In carrying out the first part of my
Invention I use the arrangement of blast pipe and nozzle tube shewn in Figures 1,
2, 2, and 3, Sheet I., Fig. 1 being a vertical section, Fig. 2 a sectional plan view,
Fig. 2, a cross section of the nozzle tube, and Fig. 3 a cross section taken in the
line x, x, of Fig. 1, the same letters referring to similar parts. a is a casting of gun
metal forming a steam chamber and is provided with a screw thread y, whereby it
may be screwed on to a steam supply pipe; b is a second casting of gun metal which
is secured by screws to a, the joint being made tight by solder or otherwise. In b
are bored steam holes c, c, about one fourth of an inch apart from centre to centre
and about sixteen one-hundredths (10th) of an inch in diameter at their front or
small end and continuing of this diameter backwards for about one sixth (*) of an
inch, and then widening conically until their edges meet. The central lines of these
steam holes should be parallel to the central line of the screw thread y.
.
The projecting part d of the piece b has its upper surface made parallel with the
axes of the holes c, c; g, g, is the nozzle tube made preferably of white cast iron
and in halves which when put together form a flat tube about two and a half inches
long and having a cross section of about three-sixteenths (18ths) of an inch high and
about one quarter of an inch wider than the row of steam holes. The nozzle
tube g, g, is held together and is also fastened to the piece b, d, by the clamp i.
When necessary packing pieces of thin metal or paper may be inserted between the
nozzle tube and the piece d so as to ensure that the central plane of the nozzle tube
shall coincide with the central lines of the steam holes c, c.
This adjustment is important, for if the nozzle is not accurately placed the sand
blast will strike upon one side of the nozzle tube and will soon cut it away.
In order to admit the supply of fluid mud the lower half of the nozzle tube is cut
away for about one eighth of an inch at its inner end e, and a corresponding
aperture v is made in the piece d so as to communicate with the cross tube o.
The vertical pipe f which descends to the bottom of the conical mud vessel p,
Sheet II., has a horizontal branch p¹, which is inserted in the cross tube o, and this
branch is provided with a long slit p² on its underside through which the mud enters
the tube o. By thus arranging the slit the flow of the mud is distributed. The metal
of the piece b, d, is also sloped off below the row of steam holes so as to facilitate
the entrance of the fluid mud from the tube o into the nozzle tube; all the joints
between and around the nozzle tube are made air tight by red lead putty. By this
arrangement of a number of small holes placed in a row, side by side, the fluid mud
is drawn by the suction between and around the separate jets of steam, all of which
blow into the same nozzle tube and thus produce a more uniform sand blast which
has little or no tendency to make the surface of the file concave or hollow.
Fig. 1, Sheet II., shows in elevation, and Fig. 2 in plan view, the mode of
mounting the apparatus for use. 8, Fig. 1, is the settling chamber in which the
fluid mud is collected after being used; it consists of a wooden box about six feet
cube which slopes towards the front, and also towards a gutter in its centre; t is
the working hole, about four inches long and two-and-a-half inches high, in the
front of the chamber 8.
In these Figures two blast pipes are shewn one above the other, below the file to
be treated. It will be seen that their nozzles are considerably wider than the file
treated, and are so arranged that the upper one inclines downwards (say about
twenty-five degrees from the horizontal), and to one side (say to the left) about
eleven degrees from the longitudinal axis of the file, while the lower one inclines
upwards and to the other side (say to the right) at similar angles.
For most files this sideway inclination of about eleven degrees will direct the
sand blast nearly at right angles across the last cut of the file, and if necessary this
sideway inclination should be altered so as to ensure this direction of the blast.

page_text: sides at equal-angles-to-the-two-sand-blasts..
In this way all the four sides of a flat or square file may be sharpened simulta-
neously.
The vertical distance between the ends of the nozzle tubes will depend on the
thickness of the files treated; but for files of about three-eighths of an inch
thick, about one-and-a-half inches from centre to centre of the ends of the nozzle
tubes, as shewn in Fig. 1, will be found convenient..
The horizontal distance from centre to centre of the ends of the nozzle tubes, as
shewn in Fig. 2, may be about one and an eighth inches.
As files of different fineness of teeth and different degrees of dullness ought to
receive corresponding degrees of grinding, it is desirable that the workman should
possess some means of ascertaining at cach instant of the operation the effect pro-
duced on the file, and the condition of every part of its surface.
For this purpose a bar of metal h, Fig. 1 (generállý gun metal), which will be
called the "feeler," is secured to one of the blast pipes in such a manner that as
the workman moves the file under the blast he can keep it slightly pressed against
the "feeler." While the file is dull it slides easily over the "feeler," but as the
sharpening progresses the workman will find that it begins to "bite," and he can
thus test it through its whole length, and on each side, and judge when it is
sufficiently sharpened. As the end of the "feeler" is cut away by the rubbing of
the file the feeler" h is pushed forward.
A lateral guide w (Fig. 2) may also be secured to the front of the chamber 8.
This lateral guide may consist of a piece of smooth hard steel bar.
For good working it is desirable that the fluid mud should have an uniform
consistency (say about spec. grav. 1.44 or 1/4 lbs. to an imperial pint.)
In an ordinary tub or box the tendency of the solid matter to settle to the bottom
is apt to cause irregularity unless the mixture is frequently stirred. To prevent
this irregularity and obviate the necessity for frequent stirring the mud vessel is
made in the form of an inverted cone, and the supply of mud is drawn from near
the point. As the horizontal area of this vessel decreases towards the bottom the
current is proportionately more rapid, and it is found that the supply is made more
regular and the suction tubes are less apt to become choked.
The two converging blast pipes a, a, drive the steam and mud through the hole t
into the settling chaniber 8, where the mud and water fall to the bottom and return
by the gutter to the conical mud vessel p, from which it is again sucked up by the
tubes ff, into the blast pipes and reused, the waste steam and air escaping to a
chimney connected with the settling chamber s.
The sand used in the state of fluid mud to feed the blast pipe is about as fine as
flour emery. Beyond 'a 'certain degree of fineness the sand does not cut so rapidly,
though it will in time produce a keen and smooth edge. Coarse-sand-cuts rapidly,
but makes a more rough and blunt edge.
In order to make up for waste a supply of sand fine enough to pass through a
sieve of one hundred and twenty wires to an inch is put into a hopper at the side
of the chamber s, and is gradually washed down into the mud vessel.
The conical mud vessel p may be made of sheet metal, and about two feet high and
two feet in diameter at the top. A sieve is suspended near the top of the vessel to
catch any dirt, and also to break up the stream of mud as it runs from the
chamber 8.
The mud vessel p is provided with a suitable overflow pipe placed about half an
inch above the level of the sieve, so that the excess of water carrying with it some
of the finest mud will run off to another receptacle, where the solid matter will be
allowed to settle.
Before being exposed to the sand blast it is desirable that the files should be
cleaned by being boiled with caustic alkali, and any "pins" or "choaks" of metal
between the teeth should be removed.
In operating with steam and fluid mud in the round blast pipes referred to in

page_text: the Letters Patent above recited, I find that it is better to introduce the mud from
an outside aperture, so that it is drawn around and into the steam jet which issues
from a central pipe or hole, and in this way a larger proportion of sand to steam can
be used, and a better cutting effect produced than if the mud is introduced by the
central pipe and the steam on the outside.
This arrangement is shewn in Fig. 5, Sheet I. a is the central steam pipe which
may have a bore about inch in diameter; b is the nozzle tube about six inches
long, and -inch in bore; c is the tube through which the fluid mud is sucked
into the annular groove around the end of the steam pipe, and is then blown
through the nozzle tube.
In cases where it is desired to operate to an uniform degree by the sand blast
upon a great number of small articles, there has been a difficulty in holding and
turning them under the blast, so as to ensure that all parts shall be properly acted
on, particularly if they are of irregular shapes. The second part of my Invention is
directed to this object, and I propose to turn the sand blast upwards into the
funnel shaped bottom of a high vessel, so arranged that the articles slide down the
funnel by gravity into the blast which immediately throws them upwards, when
they again fall upon the funnel and slide down into the blast, and are thus kept by
it in circulation and rotation with exposure of all parts to its action.
The size and shape of the vessel and the force of the sand blast employed are
proportioned to each other, and to the size, weight, and surface of the articles
treated, so that a proper circulation may be maintained.
When the articles are light I propose to use a current of air (produced preferably
by a suitable exhausting machine) to propel the sand; and to avoid breakage when
the articles are brittle elastic linings are provided at the places where the articles
would strike with velocity.
A tube open at both ends may be arranged in the vessel so as to receive the
ascending sand blast and the articles carried up with it, and to separate them from
the space where the articles are falling back towards the blast, and thus facilitate
the circulation. Suitable sieves are provided to retain the articles in the vesseļ
while allowing the spent steam or air and sand to escape. Grain may be treated
in this way for the removal of the exterior hull.
Fig. 4, Sheet I., shews an apparatus arranged to treat small articles, and to be
worked by a current of air produced by a vacuum of about one pound per square
inch.
a, a, is a cylinder of sheet iron about nine inches in diameter and four feet
high, having a funnel shaped bottom ending in the tube b, b, and measuring about
one inch in diameter and two feet long. The upper part of a, a, is perforated
with numerous holes too small to pass the article treated, but allowing free escape
to the air and sand
c, c, c', c¹, is another cylinder of sheet iron about fifteen inches diameter and five
feet high surrounding a, a, and b, b, and communicating by the pipe d with a
suitable air exhausting machine; c', c', is open at bottom; e, e, is a cap which fits
tight round the tube b, b, and has a rim which rises to a little above the level of
the bottom of c², c¹, and is about two inches larger in diameter than c¹, c'; sand
is placed in c¹, c¹, up to the level of the funnel, and filling the cap e, e, it closes the
bottom of c, c. The height of this column of sand must be sufficient to withstand
the upward pressure of the vacuum used.
To the bottom of e, e, is adjusted a horizontal tube i ending in an open funnel
mouth, and having also a vertical outlet m directly under the tube b, b.
The cap e, e, has a hole n for the passage of sand which is regulated by a valve
plate o, and a corresponding hole is made in the tube i.
The operation is as follows:-The outlet m is closed, the sand valve is opened;
a valve in the pipe & is opened and the exhausting machine draws the air from
the vessel a, a, and causes a rapid current of air carrying a stream of sand with
it to enter through the tube b, b. A suitable quantity of the articles to be treated

page_text: is gradually dropped into the funnel h, which articles are drawn up by the air
through the tube b, b.
The-articles-are-then-constantly-thrown
upwards_through_the_central_tube_p,
and fall back upon the funnel and sliding down to its centre are again struck
-by-the-blast,-and-thrown-upwards receiving at each passage the cutting action
-of-the sand blast while-being-rotated so as to expose all sides in turn.
- When they are judged-to-be sufficiently acted upon, the sand valve is closed;
the outlet m is opened, and the air valve in the pipe d is gradually closed, and
the articles drop through the pipe b, b, and the outlet m.
The waste air and sand pass through the holes in the vessel a, a, and the sand
falls to the bottom of the outer vessel c, c, and is reused, while the air escapes_
upwards round the baffle plate 8, 8, to the exhaust pipe d.
In the foregoing description certain forms, dimensions, angles, and distances of
the apparatus have been mentioned because they have been found to give good
results, but it is not intended to confine the Invention thereto, as they may be
varied without changing the substantial character of the apparatus.
Having now set forth the nature of my Invention of "Improvements in the
Mode of Employing the Sand Blast and in the Apparatus therefor, Particularly
Applicable to Sharpening Files and other Tools, and to Cutting, Cleaning, and
Frosting Metallic and other Surfaces," 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 arrangements of apparatus as shewn and described for
effecting the objects of the said Invention; I claim particularly,-
First. The use of one or more interior steam jets combined with an exterior
supply of fluid mud or fine sand mixed with water for producing a sand blast.
Second. The use of a wide and thin sand blast, the steam entering either by one
or more wide and thin apertures or by a row of small holes, there being intervals
between the jets to which fluid mud is supplied.
Third. The use of a feeler as described for testing the progress of the sharpening
of files during the operation.
Fourth. The conical mud vessel from the small end of which the fluid mud is
drawn.
Fifth. The use of a sand blast directed at an angle to the length of the file so as
to act simultaneously on two adjacent sides, as and for the purpose described.
Sixth. Nozzle tubes made of two or more pieces of cast iron or steel, as and for
the purpose above described.
Seventh. Obtaining by means of the sand blast the motion, rotation, or
circulation of the articles to be acted upon requisito for presenting all surfaces
of such articles to the action of the blast.
In witness whereof, I, the said Benjamin Chew Tilghman, have hereunto set
my hand and seal, the Twenty second day of January, in the year of our
Lord One thousand sight hundred and nighty