IMPROVE- MENTS IN MACHINERY FOR CUTTING FILES
Year: 1864

page_text: LETTERS PATENT to George Tomlinson Bousfield, of Loughborough
Park, Brixton, in the County of Surrey, for the Invention of "IMPROVE-
MENTS IN MACHINERY FOR CUTTING FILES."-A communication from abroad
by William Thomas Nicholson, residing at Providence, Rhode Island,.
United States of America.
Sealed the 8th August 1864, and dated the 23rd May 1864.
PROVISIONAL SPECIFICATION left by the said George Tomlinson
Bousfield at the Office of the Commissioners of Patents, with his
Petition, on the 23rd May 1864.
I, GEORGE TOMLINSON BOUSFIELD, of Loughborough Park, Brixton, in the
County of Surrey, do hereby declare the nature of the Invention for "Iм-
PROVEMENTS IN MACHINERY FOR CUTTING FILES," to be as follows:-
Machinery for cutting files has often been attempted, but has rarely been
practically useful, and in no instance has been capable of producing all the
various grades of files as perfectly as the same could be made by hand labor:
The obstacles which stood in the way of success have been various, and
have arisen from the varying conditions under which the machine must
accomplish a uniform work, due principally to the irregular form of the blank;
the four faces of which, during a portion of their length, are more or less curved,
so that in passing under the cutter the spaces between any two cuts will, with
a uniform feed motion, vary in proportion to the curvature of the face of the

page_text: blank. Again, as it is necessary to impart to the cutter an impulse which
shall be proportioned in intensity to the varying resistance due to the shape of
the file blank, which impulse is obtained from a spring, the tension of which is
according to the requirements of the work to be done by the cutter, increased
or diminished; it is obvious that unless such a relation subsists between the
mechanism for feeding the file under the cutter and the mechanism by which
the force of the blow is varied, as insures perfect regularity of movement
without loss of motion in any of its parts; the successive cuts will be of
irregular depth and of unequal distances apart, and the work produced con-
sequently imperfect. Furthermore, it is necessary that there should be some
means for compensating the force which the spring shall impart to the cutter,
as, for instance, in case the maximum force which a certain spring is capable of
exerting upon the cutter is just short of that necessary to effect the proper cutting
of the blank at its widest part, it will be necessary to substitute another spring
of greater power, but this latter spring may exert a force as much too great for
the proper execution of the work as the other was too feeble, so that without
some means by which the maximum force. of each spring can be adjusted
independently of the mechanism which varies the intensity of its force between
the limits which it possesses, a failure to accomplish a useful. result would from
this cause ensue.
Now, the object of this Invention is so to construct machines for cutting
files as to overcome these mechanical difficulties. For this purpose a machine
is constructed in the following manner:-The cutter is carried by a frame
capable of working to and fro vertically between guides carried by a pedestal
or bed; the frame is actuated by a tappet or cam on the main shaft in the
upward direction, and by its gravity, aided by a spring presently to be described,
in the other direction. The carriage upon which the blank to be cut is placed,
and which is more particularly described with its improvements in another
part of this Specification, travels upon a bed which rests upon the pedestal of
the machine; this bed can be adjusted obliquely to the plane in which the
frame which carries the cutter chisel travels. For this purpose the bottom of
the bed has formed upon it midway between its extremities a semi-cylindrical
projection, which is received in a corresponding semi-cylindrical cavity in the
pedestal. The blank to be cut is placed upon the carriage directly under the
cutter, and is held down during the cutting operation by any of the methods
in use. The carriage with the blank secured to it is made to travel under the
cutter so as to allow of the formation of the successive teeth, as follows:
Upon the extremity of the main shaft opposite to the end at which the power
is applied is placed a' disc plate, which is furnished with a wrist pin attached

page_text: to a slide adjustable in a groove in the plate. A shackle bar connects the
wrist pin with a similar pin attached to the lower end of a perpendicular rod,
which is fitted to work in a guide carried by the framing of the machine,.
whereby the revolution of the main shaft imparts a reciprocating motion to
the perpendicular rod, the range of which motion can be increased or
diminished by adjusting the wrist pin nearer to or farther from the centre of
the disc plate, and, as will presently be described, thereby vary the rate of
speed at which the blank will be moved under the cutter. Each extremity of
the perpendicular rod has projecting from it at right angles a fixed arm; to
each of these arms is attached one end of a steel band or ribbon. The other
ends of the two bands are made fast to the face of a drum, around which each
makes a partial turn, the face of the drum being of sufficient width to allow
of the bands being arranged side by side, and to allow of the bands lying side
by side on the drum, one of the arms projecting from the perpendicular ród is
made longer than the other by at least the width of one of the bands. A nut
and screw upon the end of one of the bands affords the means for tightening
their strain upon the drum if necessary. It is obvious that the reciprocating
motion of the rod will by means of the bands impart a rocking motion to the
drum. The drum is fitted to turn freely on the shaft upon which it is
mounted in one direction, but on its side it carries a pawl, which when the
drum is turned in the other direction engages with the teeth of a ratchet
wheel upon the shaft, and causes the shaft to be turned. This shaft is
mounted in bearings upon a carriage, which can be moved for a short distance
upward or downward upon a guide attached to the side of the frame of the
machine, and on this shaft is a screw which can be caused to engage with
screw teeth on the periphery of a worm wheel when the carriage which carries
the screw is brought down into such a position as to allow of this being done.
The intermittent rotary motion which the drum with its screw receivės
through the mechanism above described, causes the worm wheel to be turned
and with it the shaft to which it is keyed. This shaft passes through the
central, portion of the semi-cylindrical projection upon the under side of the
bed that supports the carriage upon which the file blank is carried; upon this-
shaft is a drum, around a portion of the circumference of which two metallic
bands or ribbons pass side by side, one end of each band being made fast to
the face of the drum, and the other end of each connected to the carriage that
carries the file blank. It is clear that as the shaft is turned one of the bands
will be wound upon the drum, and the other be at the same time unwound;
and the carriage will be moved along its bed. By this means the blank to be
cut is fed' under the cutter at any proper rate of speed to produce the distance

page_text: between the successive cuts desired, inasmuch as the extent to which for each
cut the carriage which carries the blank shall be moved is dependent upon
the extent to which the screw is turned, and this again is dependent upon the
extent of the arc of vibration of the drum which turns around the axis of the
screw, and this can be regulated at pleasure by the adjustment of the wrist
pin with reference to the centre of the disc plate on the main shaft..
It should be observed that by the use of metallic band connections between
the main shaft and the feeding gear, and between the feeding gear and the
carriage, which can always be kept taut by the straining nuts, all back lash or
loss of motion will be prevented. It has already been stated that the force of
the blow given by the chisel is aided by the action of a spring. This agency
is employed in most machines, but in this Invention there are some novelties
of application, which are as follows:-A rocking shaft is employed, which
works in journals attached to the upper part of the framing; a longitudinal
mortise is formed through the whole length of this shaft; in this mortise a
flat spring of steel is placed. Several of these mortises may be made, or one
alone may be had of sufficient capacity to allow of the insertion of several
springs. The shaft is divided transversely into two lengths, which are con-
nected together in such manner that one portion can turn upon the other.
Upon the end of the shaft on the opposite side of the machine from the
toothed gear feeding wheel before mentioned is placed, so that it can turn
thereon, a collar having an arm projecting from it; the collar can be set in
any position on the shaft by a screw carried by the collar working into the
teeth of a toothed wheel keyed fast to the shaft, and when the end of the arm
projecting from the collar is connected to a rod which by mechanism presently
to be described is prevented from rising, any amount of torsional strain can be
put on the spring by turning the screw, the rod can be connected to the arm at any
distance from the shaft, and the leverage of the arm so regulated. Upon the
opposite length of the shaft to the length that carries the arm above mentioned
is an arm which bears upon the sliding frame that carries the cutter shisel,
and so forces the frame downwards when the frame is free to descend. The
mechanism for giving an increased blow to the chisel when it is to act upon
the wider portion of the blank where the resistance is greater than at the
parts where the blank is narrower is as follows:-Upon the shaft that carries
the feed wheel, but upon the side of the machine opposite to that where the
feed wheel is placed, there is a disc plate, upon the face of which is a cam
which can be adjusted to any position upon the plate by means of clamp
The rod that is connected with the arm on the shaft containing the
spring above mentioned has a projection upon it, which can be adjusted to
screws.

page_text: any position on the rod; this projection is so placed as to bear against the
face of the cam, and is held in position by a set screw. The disc plate and
cam being on the same shaft as the feed wheel turns with it.
The acting face of the cam will necessarily as it revolves bear down the rod
which will carry down the arm on the shaft containing the spring, and so
increase the strain upon the spring within it, and by adjusting the cam, so
that this effect will be produced during the length of time that the wider
portions of the blank are being cut, the force of the blow which the chisel will
give when the frame that carries it is released from the tappet or can on
main shaft will be greater than when by the action of the face of the cam the
tension of the spring is less. This arrangement of the spring described in
view of the purposes to be accomplished is of importance, from the fact that a
small extent of movement of the arm on the rocking shaft will greatly
increase the power and activity of the spring, while the arın on the shaft
being slotted allows of considerable variation in the leverage of the arın for
twisting the spring; and this, together with the capacity already explained for
the introduction of more than one spring into the shaft allows of the requisite
degree of power for effecting the proper depth of cut being readily obtained.
Another feature of this Invention consists in a means for imparting a variable
feed motion to the file blank. The majority of files are made nearly flat from
the shank to about the middle, and then commence to taper toward the point
with a gradual curve. In all hand-cut files the lands are made wider near the
middle of the file than at the ends, but in a machine-cut file, which fed with
a uniform speed, the lands will be widest where the curve of the face of the
file is greatest, leaving the lands near the central part narrower than toward
the point. To make the machine-cut file in this respect like those made by
hand, the feed wheel is so constructed that it can be set eccentrically upon its
shaft by means of clamp screws, which attach the wheel to a disc plate on the
shaft. The screw which actuates the feed wheel, together with the carriage
that carries it, can, as already explained, rise and fall upon a slide carried by
the framing, so that in revolving the feed wheel it can readily be aided by the
band connections to accommodate itself to the eccentricity of the latter. It
is apparent that the greater the distance between the axis of the feed wheel
and its periphery at the points acted upon by the screw the less will be the
extent to which the file blank will be fed along, and vicè versa; and by so
adjusting the speed wheel that the more rapid rate of feed shall occur while
the central portion of the file is being cut it is apparent that the result to be
desired will be accomplished.
Another feature of this Invention consists in a means of arresting the

page_text: As the carriage travels
of the bar, and by the
action of the cutter after any previously determined portion of the blank has
been cut for the purpose of diminishing the degree of attention required on
the part of the operator, and to enable one person to attend upon a number
of machines at the same time. For this purpose a bar is fitted to slide in a
guide attached to one of the uprights of the frame of the machine. This bar
is a prism of several sides, with the exception of a small portion near the
upper end, which is cylindrical. A collar, to which a handle is attached, and
which has also a projection formed upon it, surrounds the upper part of the
bar, the handle having a mortise through it to admit the prism-shaped bar.
Upon the carriage that carries the file blank is placed an inclined plane,
which is adjustable to any position on the bed.
forward the inclined plane comes under the foot
progress of the carriage the bar is raised by the inclined plane until the
cylindrical portion of the bar, which was previously below the mortise in the
collar, has been raised until it occupies the place in the collar which was
before filled by the prism; the collar is then free to yield to the influence of a
spring, and turn far enough to bring its projecting ear under the frame which
carries the chisel, and so supports it and prevents it from again descending to
strike the file blank, at the same time the worm that gives motion to the
feed wheel is, together with the carriage that carries it, raised to stop the feed
by the direct action of a cam on the axis of a feed wheel or by the action of a
weighted lever, the long arm of which rides upon the face of a cam whose face
at that point in its revolution has been cut away to allow the lever to fall, and
cause the short arm to raise the same and its carriage above the teeth of the
feed wheel.
Another feature of the Invention consists in the application of equalizing
pressure springs or their equivalents to the said rocking bed, for the purpose
of better adapting any inequalities in the surface of the file blank to the edge
of the cutter. This is accomplished supporting the file blank on a rocking
block, which block is carried by a sliding carriage that travels on a suitable
bed; the necessity for this rocking block arises from the fact that in order to
give the proper barb to the teeth the plane in which the chisel travels, and
the plane in which the blank travels, must be inclined with respect to each
other, and as the teeth are cut in diagonal lines if the transverse plane of the
file blank remains parallel with the plane of the horizon, the edge of the chisel
will cut the teeth deeper upon one side than upon the other. If the face of
the file blank contains no inequalities of surface after the rocking bed has
been once properly adjusted the successive teeth will be uniformly cut to the
same depth, but in practice it is impossible to grind the surface of the blanks

page_text: so evenly as that some inequalities shall not exist, whereby a further capacity
of adjustment of the rocking bed to the chisel becomes necessary, and is
accomplished by the means herein described. To one end of the rocking bed
is attached a segment of a worm gear, which engages with the threads of a
worm cut upon a shaft which extends transversely through the bed that
carries the file blank, the hole in the bed through which it passes being of a
greater diameter than that of the shaft, so as to admit of an endwise as well
as rotary movement of the shaft in either -direction, each end of the shaft
terminates with a thumb-piece. The spaces between the thumb-pieces and
the sides of the bed are occupied by spiral springs, which are coiled around
the shaft, and exert a pressure in opposite directions. The tendency of these
springs is to keep the rocking bed at the angle, which will bring the face of
the blank parallel with the edge of the cutter, that is to say, after the bed has
been set as.nearly as possible in its proper position by turning the worm shaft
to the right or to the left, if there should be any uneveness of surface in the
blank which would cause the chisel to cut deeper upon one side than upon' the
other, the blow of the chisel being at first harder upon one side than upon the
other of the blank, will cause the bed to rock, which it is allowed to do by
the springs, and at the same time the the jarring which the blow of the chisel
makes will cause the worm to turn in a direction to relieve itself, and thus
readjust itself to this change in the surface of the blank.
The Invention is also equally applicable to file-cutting machines, which do
not, as in this instance, have a moveable carriage which moves with the file
blank, but which feed the blank itself over the surface of the bed, provided
that such bed is free to adapt the transverse plane of the blank to the cutter's
edge. Instead of springs a weight or weights could be used, and with' equally
good effect, exert a longitudinal strain in opposite directions upon the worm
shaft, and accomplish the same useful result.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
'by the said George Tomlinson Bousfield in the Great Seal Patent Office
on the 22nd November 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
TOMLINSON BOUSFIELD, of Loughborough Park, Brixton, in the County of
Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of May, in the year of our Lord

page_text: One thousand eight hundred and sixty-four, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said George Tomlinson Bousfield, Her special licence that I, the said
George Tomlinson Bousfield, my executors, administrators, and assigns, or
such others as I, the said George Tomlinson Bousfield, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from time,
to time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN MACHINERY FOR CUTTING FILES," a
communication to me from abroad by William Thomas Nicholson, a person
resident at Providence, Rhode Island, United States of America, upon the
condition (amongst others) that I, the said George Tomlinson Bousfield,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and ascer-
tain the nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent Office.
within six calendar months next and immediately after the date of the said.
Letters Patent.
NOW KNOW YE, that I, the said George Tomlinson Bousfield, do
hereby declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :-
Sheet 1, Figure 1, is a front elevation; Figure 2, a side elevation; Figures
5. 6, and 7 are detailed parts to be referred to hereafter. Sheet 2, Figure 3,
is a side elevation, with a portion of the feed wheel removed; Figure 4
exhibits the means by which the sliding carriage which carries the file blank
is moved. Sheet 3, Figures 8 and 9, shew a means for producing a variable
feed. Sheet 4, Figure 1, is a perspective view of the moveable bed, with a
means attached for making the face of the file blank always parallel to the
cutter's edge; Figure 2 is a transverse section of the same slightly modified.
Machinery for cutting files has often been attempted, but has rarely been
practically useful, and in no instance has been capable of producing all the
various grades of files as perfectly as the same could be made by hand labor.
The obstacles which have stood in the way of success have been various, and
have arisen from the varying conditions under which the machine must i
accomplish a uniform work due principally to the irregular form of the blank,
the four faces of which, during a portion of their length, are more or less
curved, so that in passing under the cutter the spaces between any two cuts

page_text: will, with a uniform feed motion, vary in proportion to the curvature of the
face of the blank. Again, as it is necessary to impart to the cutter an
impulse which shall be proportioned in intensity to the varying resistance due
to the shape of the file blank, which impulse is obtained from a spring, the
tension of which is according to the requirements of the work to be done by
the cutter increased or diminished. It is obvious that unless such a relation
subsists between the mechanism for feeding the file under the cutter and the
mechanism by which the force of the blow is varied as insures perfect regu-
larity of movement without loss of motion in any of its parts, the successive
cuts will be of irregular depth and of unequal distances apart, and the work
produced consequently imperfect. Furthermore, it is necessary that there
should be some means for compensating the force which the spring shall
impart to the cutter; as for instance, in case the maximum force which a
certain spring is capable of exerting upon the cutter is just short of that
necessary to effect the proper cutting of the blank at its widest part, it will
be necessary to substitute another spring of greater power; but this latter
spring may exert a force as much too great for the proper execution of the
work as the other was too feeble, so that without some means by which
the maximum force of each spring can be adjusted, independently of the
mechanism which varies the intensity of its force between the limits which
it possesses, a failure to accomplish a useful result would from this cause
ensue.
In this Invention, while some of the same general principles are involved.
which have characterized other machines, I have introduced features of con-
struction and methods of arrangement which combine simplicity of structure
and accuracy of operation beyond any existing machine of its class with
which I am acquainted, and which enable me to overcome the various
mechanical difficulties in the way of former machines which I have above.
referred to.
In the accompanying Drawings A is a pedestal or bed of the machine;
B, B, are guides, between which the frame B', B', which carries the cutter is
made to work in a plane perpendicular to the plane of the horizon, and which
is actuated by the tappet C on the main shaft C¹ in the upward direction, and
by its gravity, aided by a spring, presently to be described, in the other
direction. The carriage D upon which the blank to be cut is placed, and
which is more particularly described, with its improvements, in another part
of this Specification, travels upon a bed D', which can be adjusted obliquely to
the plane in which the frame which carries the cutter chisel travels, and
which rests upon the pedestal A, a semi-cylindrical cavity being formed in the,

page_text: latter to receive the corresponding semi-cylindrical portion D" (Figure 4,
Sheet No. 2,) which projects from the under side midway between the extre-
mities of the bed. The blank to be cut is supposed to be placed upon the
bed of the carriage D, directly under the cutter, and to be secured and held
down during the cutting operation by any of the methods in use.
No special
means for this purpose are shewn in the Drawings, as various contrivances
can be employed. The carriage D, with the blank secured to it, is made to
travel under the cutter, so as to allow of the formation of the successive teeth,
as follows:-Upon the extremity of the machine shaft c³, opposite to the end
at which the power is applied, is placed a disc plate E, (Figure 3, Sheet No. 2,)
which is furnished with a wrist pin a attached to a slide b, adjustable in a
groove c in the plate. A shackle bar F connects the pin a with a similar
pin d attached to the lower end of the perpendicular rod G, which is fitted to
work in the guide G¹, whereby the revolution of the main shaft C' imparts a
reciprocating motion to the rod, the range of which can be increased or
diminished by adjusting the wrist pin a nearer to or farther from the centre
of the disc plate E, and, as will presently be seen, thereby vary the rate of
speed at which the blank will be moved under the cutter. Projecting from
the rod G at each extremity, and at right angles with it, are fixed arms e, e¹,
to which at one of their ends are attached the steel bands or ribbons f, f.
The other ends of these bands are made fast to the face of the drum, around
which each makes a partial turn, the face of the drum being of sufficient
width to allow of the bands being arranged side side, and the length of the
arm e being greater than that of the arm e¹ by at least the width of one of
the bands. A nut and screw 9 upon the end of one of the bands afford the
means for tightening their strain upon the drum if necessary. It is obvious
that the reciprocating motion of the rod G will, by means of the bands,
impart a rocking motion to the drum H. The drum H is fitted to turn freely
on the shaft I, upon which it is mounted in one direction, but on its side it
carries a pawl, (not shewn in the Drawing,) which, when the drum is turned
in the other direction, engages with the teeth of a ratchet wheel h upon the
end of the shaft I, and causes the shaft to be turned. This shaft is mounted ·
in bearings j, j, upon a carriage, which can be moved for a short distance
upward or downward upon a guide L attached to the side of the frame B,
and carries a screw J, the threads of which will engage with the teeth on the
periphery of the gear wheel K, when the carriage which carries the screw is
brought. down to allow of this being done. The intermittent rotary motion,
which the shaft I with its screw J receives through the mechanism above
described, causes the gear wheel K to be turned, and with it the shaft M to

page_text: which it is keyed (Figure 1, Sheet No. 1). This shaft passes through the
central portion of the semicylindrical projection D" (Figure 4, Sheet No. 2,)
upon the under side of the bed D', and carries a drum N. Two metallic
bands or ribbons pass side by side partially around this drum, (as shewn
by dotted lines, and also in Figure 8, Sheet No. 3,) one end of each
band being made fast to the face of the drum, and the other end of each
connected to the carriage D at its front and rear end by a straining nut and
screw. It is clear that as the shaft M is turned one of the bands will be
wound upon the drum, and the other be at the same time unwound, and the
carriage D will be moved, along its bed. By this means the blank to be cut
is fed under the cutter at any proper rate of speed to produce the distance
between the successive cuts desired, inasmuch as the extent to which for each
cut the carriage D which carries the blank shall be moved is dependent upon
the extent to which the screw J is turned, and this again is dependent upon
the extent of the arc of vibration of the drum H, which can be regulated at
pleasure by the adjustment of the wrist pin a with reference to the centre of
the disc plate E. In this connection it should be observed, that by the use.
of metallic band connections between the main shaft and the feeding gear,
and between the feeding gear and the carriage, which can always be kept tort
by the straining nuts, all back lash or loss of motion will be prevented. It
has already been stated that the force of the blow given by the chisel is aided
by the action of a spring. This agency is employed in most machines, but in
this Invention there are some novelties of application, which are as follows:-
O is a rocking shaft (Figures 1, 2, and 7, Sheets Nos. 1 and 3) which works
in journals attached to the uprights B, B, of the frame; O¹ (shewn in blue)
is a flat piece of spring steel, which is placed in a longitudinal mortice
extending through the axis of the shaft. Several of these mortices may be
made, or one alone may be had of sufficient capacity to allow of the insertion
of several springs. The shaft is made in two parts, which are connected
together by a slip joint n, as shewn. in Figure 6, Sheet No. 1, so that one
portion can turn upon the other. Upon the end of the shaft on the opposite
side of the machine from the toothed gear feeding wheel is placed, so that it
can turn thereon an arm O", which by means of the screw e mounted in
brackets upon the head of the arm working into the teeth of a toothed wheel
m keyed fast to the shaft can be adjusted in its position upon the shaft, and
when the end of this arm O" is connected with other mechanism, presently
to be described, so as to resist the action of the screw k, the spring O' will
torsionally be strained, and an increased impulse proportioned to the increased
tension of the spring be given to the arm p, which acts upon the sliding

page_text: frame which carries the cutter chisel. The mechanism for giving an increased
blow to the chisel when it is to act upon the wider portion of the blank,
where the resistance is greater than at the parts where the blank is narrower,
is as follows:-Upon the shaft M, but upon the side of the machine opposite
to that where the wheel K is located, is placed a disc plate P, upon the face
of which is a cam P', which can be adjusted to any position upon the plate
by means of clamp screws. The rod P has its upper end connected with
the arm 0" by a pin, which can be adjusted as desired to any position in the
slot q in said arm. The lower portion of the rod P" passes through a guide r
projecting from the pedestal of the machine. A foot Q, which is adjustable
on the rod P", is so placed as to bear against the face of the cam P', and is
held in position by a set screw. The disc plate P being on the same shaft as
the feed wheel K turns with it, and consequently the cam P' is rotated also.
The acting face of the cam will necessarily as it revolves bear down the rod
P", which will carry down the arm 0" and increase the torsional strain upon
the spring O', and by adjusting the cam P' so that this effect will be pro-
duced during the length of time that the wider portions of the blank are
being cut, the force of the blow which the chisel will give when released from
the tappet C, (Figure 1, Sheet No. 1,) will be greater when by the action of
the face of the cam the tension of the spring is less. This arrangement of
the spring described in view of the purposes to be accomplished, is of
importance from the fact that a small extent of movement of the arm 0"
will greatly increase the power and activity of the spring, while the slotted
arm 0" from the variation in the leverage to twist the spring which it admits
of, enables me with the capacity already explained for the introduction of
more than one spring into the shaft O, to obtain just the degree of power
required to effect the requisite depth of cut, so that a compensation for any
excess of force which the spring or springs would otherwise exert is readily
obtained.
In this connection another feature of this Invention should properly be
explained which is exhibited in Figure 9, Sheet No. 3, which consists in a
means for imparting a variable feed motion to the file blank. The majority
of files are made nearly flat from the shank to about the middle and then
commence to taper toward the point with a gradual curve. In all hand-cut
files the lands are made wider near the middle of the file than at the ends,
but in a machine-cut file, which is fed with a. uniform speed, the lands will
be widest where the curve of the face of the file is greatest, leaving the lands
near the central part narrower than toward the point. To make the machine-
cut file in this respect like those made by hand, I have so constructed the

page_text: feed wheel K that it can be set eccentrically upon its shaft M by means of
clamp screws 8, s, which attach the wheel to the disc plate R on the shaft.
The screw J, which actuates the. feed wheel with the carriage on which it is
hung, as already explained, can rise and fall upon the slide L, Figure 1, Sheet
No. 1, so that in revolving the feed wheel K it can readily be aided by the
band connections to accommodate itself to the eccentricity of the latter. It
is apparent that the greater the distance between the axis X, Figure 9, Sheet
No. 3, of the feed wheel and its periphery at the points acted upon by the
screw the less will be the extent to which the file blank will be fed along and
vice versa, and by so adjusting the speed wheel that the more rapid rate of
feed shall occur while the central portion of the file is being cut, it is apparent
that the result to be desired will be accomplished.
Another feature of this Invention described in this Specification consists in
a means of arresting the action of the cutter after any previously determined
portion of the blank has been cut for the purpose of diminishing the degree
of attention required on the part of the operator and to enable one person to
attend upon a number of machines at the same time.
The arrangement of devices is shewn in Figure 1, Sheet No. 1; a bar t
(also Figure 5, same Sheet) is fitted to slide in a guide attached to one of the
uprights B of the frame of the machine. This bar is a prism of several sides,
with the exception of a small portion near the upper end, which is cylindrical,
a collar u, to which a handle is attached and which has also a projection v
surrounds the upper part of the prism w, it having a mortice through it to
admit the prism. Upon the carriage D is placed an inclined plane which is
adjustable to any position on the bed. As soon as the foot of the bar t com-
mences in the progress of the carriage beneath it to ascend the face of the
inclined plane the cylindrical portion of the bar which is then below the
mortice in the collar will begin to be raised until it occupies the place in the
collar which was before filled by the prism, when the collar is free to yield to:
the influence of the spring y, (Figure 5, Sheet. No. 1,) and turn far enough to
hinge the projecting ear under the frame B¹ which carries the chisel and
supports it, at the same time the worm screw J with its carriage is raised to:
stop the feed by the direct action of a cam Z, Figure 1, Sheet No. 1, on the
shaft W located beneath it, or by the action of a weighted lever the long arm
of which rides upon the face of a cam, whose face at that point in its revolution
has been cut away to allow the lever to fall and cause the short arm to raise.
the same and its carriage above the teeth of the fixed wheel.
Another feature of the Invention consists in the application of equalizing
pressure springs or their equivalents to the said rocking bed for the
purpose of

page_text: better adapting any inequalities in the surface of the file blank to the edge of
the cutter.
In the accompanying Drawings (Sheet No. 4) D is the moveable carriage,
which travels upon an appropriate bed, and D" the rocking block upon which
the blank is placed, the necessity for which rocking block arises from the fact
that in order to give the proper barb to the teeth the plane in which the
chisel travels, and the plane in which the blank travels, must be inclined with
respect to each other, and as the teeth are cut in diagonal lines, if the trans-
verse plane of the file blank remains parallel with the plane of the horizon, the
edge of the chisel will cut the teeth deeper upon one side than upon the other.
If the face of the file blank contains no inequalities of surface after the rocking
bed has been once properly adjusted the successive teeth will be uniformly cut
to the same depth, but in practice it. is impossible to grind the surface of the
blanks so evenly as that some inequalities shall not exist, whereby a further
capacity of adjustment of the rocking bed to the chisel becomes necessary and
is accomplished by the means herein described. To one end of the rocking
bed is attached a segment of a worm gear 1 (Figure 1) which engages with
the threads of the worm 2 (same Figure) cut upon a shaft which extends
transversely through the bed D, the hole in the bed through which it passes
being of a greater diameter than that of the shaft so as to admit of an endwise
as well as rotary movement of the shaft in either direction, each end of the
shaft E terminates with a thumb-piece 3, 3, the places. between the thumb-
pieces and the sides of the bed D are occupied by spiral springs 4, 4, which
are coiled around the shaft and exert a pressure in opposite directions. The
tendency of these springs is to keep the. rocking bed at the angle which will
bring the face of the blank parallel with the edge of the cutter, that is to say,
after the bed has been set as nearly as possible in its proper position by turning
the worm shaft to the right or to the left if there should be any unevenness of
surface in the blank which would cause the chisel to cut deeper upon one side
than upon the other, the blow of the chisel, being at first harder upon one side
than upon the other of the blank, will cause the bed to rock, which it is
allowed to do by the springs, and at the same time the jarring which the blow:
of the chisel makes will cause the worm to turn in a direction to relieve itself
and thus readjust itself to this change in the surface of the blank.
The Invention is also equally applicable to file-cutting machines which do
not, as in this instance, have a moveable carriage which moves with the filo
blank, but which feed the blank itself over the surface of the bed, provided that
such bed is free to adopt the transverse plane of the blank to the cutters'
edge
'

page_text: used, as shewn by an ar-
with equally good effect
Instead of springs a weight or weights could be
rangement exhibited in Figure 2, same Sheet, and
exert a longitudinal strain in opposite directions upon the worm shaft, and
accomplish the same useful result.
I do not limit myself. to the precise construction and arrangement of the
several parts as described, but mean to cover all mere formal variations accom-
plishing the same mode of operation so far as relates to my Invention by
equivalent means.
What is claimed as my Invention and is desired to be secured by Letters
Patent is,―
First, the method substantially as described of imparting motion to the
feeding mechanism in a file-cutting machine by the combination of a pawl
and ratchet gear or its equivalent with the bands f, f, operated by the revo-
lution of the main shaft in the manner substantially as specified.
Second, the combination of the feeding mechanism and the moveable
carriage upon which the blank is held during the cutting operation in a
file-cutting machine by the means substantially as described for the purposes
specified.
Third, imparting a variable rate of motion to the carriage upon which the
blank is held by the method and on the principle substantially as described for
the purposes specified.
Fourth, the combination of a spring or springs O', which can be torsionally
strained, as shewn, with the mechanism for varying the tension of the same
substantially as described for the purposes specified.
Fifth, the combination of a spring or springs O', which can be torsionally
strained, as shewn, with the mechanism consisting of the slotted arm 0" and
the worm gear k, m, or the equivalent of the same, for adjusting the tension
of the spring or springs within limits which will best give the proper degree
of impulse to the cutting chisel substantially as described.
Sixth, the combination of a spring or springs o', which can be torsionally
strained, as shewn, with the carriage B', B', or other device which carries the
cutting chisel substantially as described.
Seventh, the method of arresting the action of the cutting chisel at any
previously determined point in the progress of the blank under the cutter, of
the combination of a spring stop (Figure 5, Sheet No. 1,) substantially as
described, with an adjustable inclined plane upon the moveable carriage, as
herein specified.
Eighth, the method, substantially as described, of regulating the position

page_text: of the rolling bed of a file cutting machine by means of equalizing springs or
their equivalents applied and operating substantially as herein specified.
In witness whereof, I, the said George Tomlinson Bousfield, have hereunto
set my hand and seal, this Ninth day of November, in the year of our
Lord One thousand eight hundred and sixty-four.
GEO. T. BOUSFIELD. (L.s.)