CERTAIN IMPROVEMENTS IN MACHINERY FOR SHAPING AND CUTTING FILES AND RASPS."
Year: 1860

page_text: LETTERS PATENT to Francis Preston, of the City of Manchester, Engineer,
for the Invention of "CERTAIN IMPROVEMENTS IN MACHINERY FOR SHAPING
AND CUTTING FILES AND RASPS."
PROVISIONAL SPECIFICATION left by the said Francis Preston at the
Office of the Commissioners of Patents, with his Petition, on the 20th
June 1860.
I, FRANCIS PRESTON, of the City of Manchester, Engineer, do hereby
declare the nature of the said Invention for "CERTAIN IMPROVEMENTS IN
MACHINERY FOR SHAPING AND CUTTING FILES AND RASPS," to be as follows:-
My improvements in machinery for shaping file blanks consists in sup-
porting a cutter in moveable bearings, and in placing a template of the shape
of the surface of the file blank in such a position that the cutter is made to
impart the shape of the template to the file blank.
The first part of my Invention of improvements in machinery for cutting
files consists in imparting a slight lateral motion in contrary directions to the
cutting tool or chisel, or to the bed or block on which the file blank is secured,
for the purpose of producing a slight irregularity in the teeth of the file,
whereby machine-made files may more closely resemble files cut by hand.
The object of this will be apparent to persons conversant with the use of
files, as the perfect accuracy of the teeth in machine-made files gives a lateral
tendency to the file when in use, whereas the slight irregularities in hand-made
files counteracts this lateral tendency; this slight lateral motion in contrary

page_text: directions may be effected in a great many ways.
A convenient mode of
accomplishing it is by connecting two toothed segments to the chisel holder,
and attaching two racks, with alternate blank spaces, to the sliding block.
When the machine is at work the racks gear alternately in the toothed seg-
ments, and impart the requisite motion to the chisel holder.
Secondly, in the application of a double swivel frame for supporting the
chisel and the ram or hammer, this frame is capable of being moved round its
vertical axis for varying the angle of the cut on the plane of the file, or for
effecting the cross cuts, and laterally to vary the angle of the cut so as to
produce teeth more or less undercut.
Thirdly, in an improved mode of applying the spring by which the blow
given to the ram or hammer is varied in proportion to the width of the file.
When the ram or hammer has been raised by a cam acting on a spring trigger,
it compresses a spring coiled around or otherwise applied to the shank of the
ram or hammer, and as soon as the cam passes beyond the trigger the ram or
hammer descends with a force due to its weight and to the strength of the
spring; the resistance of the spring is regulated by a screw and washers, or
an adjustable slide, the end of which is furnished with a worm and worm
wheel, or other gearing acted upon by suitable gearing from the driving
shaft. By this means the force of the blow is governed in proportion to the
width of the file; when the taper part of the file has been cut the regulating
apparatus is thrown out of gear.
Fourthly, in an improved mode of connecting the chisel-holder to the ram
or hammer by means of a slot, key, and spring, whereby the ram or hammer
may be raised off the chisel before the chisel is raised out of the cut, and the
chisel brought down on to the file blank before the blow is given.
Fifthly, in the application of compressed air to act as a spring for giving
the requisite impetus to the descent of the ram or hammer. To accomplish
this a piston is attached to the shank of the ram or hammer; this piston fits
in a cylinder, the capacity of which is capable of being varied by a worm wheel
and gearing as above referred to, or other suitable apparatus may be applied
to produce the requisite changes in the force of the blow.
Sixthly, in making the 'screw, by which the sliding block is traversed,
loose on its shaft, but connected to it by a clutch box when the block has
completed its traverse; the clutch box is disconnected, and the screw is then
at liberty to be turned the contrary way by hand so as to bring the block to
its original position without altering the position of the ratchet wheel; the
shaft is then connected again to the screw by means of the clutch box, and the
machine is ready to commence a fresh file blank.

page_text: Seventhly, in an improved arrangement of parts for giving the requisite
traverse to the sliding block and file after each cut has been made; this
consists of a cam on the driving shaft acting on a rack with a coiled spring
round its end. This rack acts on a pinion to which the catch is connected for
acting on the ratchet wheel fixed to the screw, by which the block is moved,
or to the shaft passing through the said screw.
Eighthly, in supporting half round files in a cylindrical block supported in
fixed centres, and bearing on the sliding block or bed; by this arrangement,
the surface of the half round file blank can be adjusted to the cutting tool, and
the force of the blow received on the centre of the sliding block.
Ninthly, in the arrangement of apparatus to keep the break tight upon
the screw by which the sliding block or bed is moved, so as to keep it always
steadily to its position or required tightness; this is effected by placing the
break nuts in a fixture attached to the bed, and by having a screw working
upon the steps held to its position by means of lock nuts, or by means of a
chain, one end of which is attached to a lever on the screw of the break, and
the other end passing over a pulley, to which is attached a weight or spring
to give the desired tightness.
I wish to observe, that the above improvements are equally applicable to
shaping and cutting rasps.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Francis Preston in the Great Seal Patent Office on the 19th
December 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANCIS
PRESTON, of the City of Manchester, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of June, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Francis Preston, Her special licence that I, the said Francis Preston,
my executors, administrators, and assigns, or such others as I, the said
Francis Preston, my executors, administrators, 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 "CERTAIN IMPROVEMENTS

page_text: IN MACHINERY FOR SHAPING AND CUTTING FILES AND RASPS," upon the condition
(amongst others) that I, the said Francis Preston, my executors or admi-
nistrators, by an instrument in writing: under my, or their, or one of their
hands and seals, should particularly describe and ascertain 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 Francis Preston, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement (that is to say) :-
The nature of my Invention of improvements in machinery for shaping files
and rasps, consists in supporting a cutter in moveable bearings, and in placing.
a template of the shape of the surface of the file or rasp blank in such a
position that the cutter is made to impart the shape of the template to the
said blank. The nature of my Invention of improvements in machinery for
cutting files and rasps consists,-
First, in the application to file and rasp cutting machines of a double
swivel frame for supporting the cutting tool or chisel, and the ram or
hammer.
Secondly, in an improved mode of applying the spring by which the blow
given to the ram or hammer is varied in proportion to the width of the
file or rasp.
Thirdly, in an improved mode of connecting the chisel-holder to the ram
or hammer, whereby the ram or hammer is raised off the chisel before the
chisel is raised out of the cut, and the chisel is brought down on to the file
blank before the blow is given.
Fourthly, in making the screw by which the sliding block is traversed loose
on its shaft, and connected to it by a clutch-box.
Fifthly, in an improved arrangement of parts for giving the requisite
traverse to the sliding block and file or rasp after each cnt has been given.
Sixthly, in an improved mode of applying friction to the screw for moving
the sliding block, or to the shaft to which the hollow screw is connected.
Seventhly, in the application of compressed air to act as a spring for giving
the requisite impetus to the descent of the ram or hammer.
Eighthly, in an improved arrangement of parts for supporting half-round
files or rasps while being cut.
And, lastly, in imparting a slight lateral motion in contrary directions to
the cutting tool or chisel, or to the bed or block on which the file blank is

page_text: a
On Sheet 1, Figure 1 is an elevation; Figure 2, an end view; and Figure 3,
plan of a machine for shaping file and rasp blanks, according to my improve-
ments. a is a bed supported on standards, and a' is a plate fixed to the bed a;
b is a slide, which is moved to and fro' on the plate a¹ by the screw c; to the
plate a¹ flanges are cast or fixed for supporting the headstocks d in which the
shaft e revolves; this shaft (or the bushes in which it works) also serve as ful-.
crum for the swing frame f, in which works the shaft g with the cutters i; to
the swing frame fis also fixed the holder h, for the antifriction roller i', bearing
on the template j. The requisite rotary motion is given to the cutters i from the
shaft e, which is driven by steam or other power; to this shaft is fixed a pinion
el, gearing into the wheel g¹ on the shaft g, on which the cutters i are fixed
The file or rasp blanks in the rough state are fixed to the slide 6 by the
set screws, and the shaper is also secured to the slide, as shewn in Figure 2;
the cutters are then made to revolve and the slide to move along the plate a¹
by turning the screw c; the attendant by pressing on the swing frame f keeps
the antifriction roller on the template j, thereby causing the cutters i to
shape the surface of the file or rasp blanks, according to the shape of the tem-
plate j. When the upper surface of the file or rasp blank has been shaped the
swing framef is raised into the position shewn by dotted lines in Figure 1, to
enable the attendant to reverse the position of the blanks.
On Sheet 2, Figure 1 is a side elevation of a file or rasp cutting machine to
which my improvements are applied; Figure 2 is a plan; Figures 3 and 4 are
end elevations; and Figure 5, a section through the support for the ram or
hammer and parts in connection therewith. a, a, are standards supporting the
bed 6; c is the moveable block to which the file or rasp blank is attached, and
which is at all times drawn towards the right-hand end of the machine in
Figures 1 and 2, by the weight co, fixed to the end of a cbain passing over the
pulley c", as in most of the file-cutting machines now in use; d is the driving
shaft revolving in bearings in the side frames e, bolted to the bed b, which is
cast with segmental projections 6; for the double-swivel frame f, f¹; the
brackets f forming the lower part of the double-swivel frame are secured to
the projections by bolts passing through segmental slots, and by moving
these brackets the angle of the cut can be varied or changed for giving the
cross cut; the support f¹, forming the upper part of the swivel frame, is bolted

page_text: to the brackets f, and can be adjusted to vary the angle of the teeth or to make
them more or less undercut; the ram or hammer, shewn best in Figure 5, con-
sists of the cylindrical piece g, around the upper part of which is coiled the
spring g', for giving the blow to the chisel; the upper end of the ram passes
through the screwed bush h, the lower part of which bears on the spring g',
and the worm wheel has an internal thread fitting in the screwed bush ;
the object of this will be explained hereafter. The ram g is connected to the
tool-holder slide i by means of the key or projection 2, which I prefer to forge
with the ram; this key fits in a slot in the slide i, to allow the slide to move
independently of the ram; the tool holder j fits in a circular hole in the lower
part of the slide i, whereby the chisel can adjust itself to the surface of the file
blank; the shank of the tool holder is furnished with a spring, by which it is
drawn back to the face of the slide previous to receiving the next blow, in the
usual manner. The ram is raised by the cams d' and d², the former acting on
a bowl projecting from the lever k, when the swivel frame f, f¹, is in the posi-
tion shewn, and the latter coming into operation when the swivel frame has
been turned partly round for giving the cross cut. The lever is connected by
an adjustable bolt to the lifting lever ¹, and both these levers vibrate in the
fulcrum stud ², passing through the eyes of the support f¹; the lifting lever k¹
acts on the spring trigger g, passing through the ram. The block c is moved
along the bed 6 by the screw 7, which passes through a nut fixed to the under
side of the sliding block c; the screw is made hollow, and through it passes
the shaft, the object of which will be described hereafter, and it is turned
round a portion of a revolution after each tooth has been cut, by means of the
cam d³ on the driving shaft acting on the upper end of the rack m, which gears
into the pinion m¹ fixed on the shaft n, to which is also fixed the lever n',
connected by the link n' to the lever 12, vibrating on the end of the shaft,
or on a bush forming part of the bearing of the said shaft; to the lever l
is also jointed the driving pall, taking into the teeth of the ratchet
wheel, fixed on the end of the shaft l'. At each revolution of the
driving shaft the ratchet wheel is moved round one tooth or more, as
desired, and it is held there by the retaining spring catch 16. The driving
pall, and the levers, shaft, pinion, and rack by which it is worked, are drawn
back so as to be ready for the next move by the spring m² coiled round
the upper part of the rack m. The shaft of the screw is supported
near one end in the friction bearing 16, consisting of two wood or other steps
fitting in a bridle. The lower step is acted upon by a screw, to which the
pulley is fixed; and to this pulley is attached one end of a weighted chain,
the object of which is to give a constant friction to the screw 1, and thereby

page_text: to prevent any play or irregularity in the action of the block c.
In cutting
parallel files, the requisite uniform impetus is given to the ram by the spring g',
which, by means of the screwed bush h, can be set so as to give a heavy or
light blow, according to the width of the file under operation; but in cutting
tapered files it is necessary to increase or diminish the force of the blow in
proportion to the width of the file. In order to accomplish this, I attach the
rack o to the block c. This rack gears into the pinion o', fixed to the same
shaft as the pulley 02. This pulley communicates motion to the pulley o³ by
the chain o'. The pulley o³ is fixed to the same shaft as the worm o³, gearing
into the worm wheel h', above referred to. The Drawing represents the various
parts of the machine in the positions they occupy when the taper end of the
file is below the chisel. At this time the lightest blow is to be given by the
ram g, and consequently the spring g' is elongated to the extent required.
When the cam d' depresses the end of the lever k, the lifting lever k¹, acting
on the trigger g², raises the ram g, and as soon as the lifting lever passes
beyond the reach of the trigger the ram descends with a force due to the
strength of the spring g'. When the cam d¹ passes beyond, the bowl on the
lever k, the springs and k', acting above and below the said lever, instantly
bring it back to its former position, and the lever ', in passing the trigger g²,
pushes it partly through the hole in the ram, from whence it is again pushed
forward by the spring shewn by dotted lines in Figure 5. When the ram iş
descending the spring , acting on the end of the tool holder slide i, brings the
cutting edge of the chisel down on the file before the ram drops on to the upper
part of the chisel to give the cut, and when the ram is rising the head of the
ram is first lifted off the end of the chisel, and then the chisel holder is raised to
lift the chisel out of the cut. This is accomplished by means of the slot in
the slide i, through which the key ¹ passes. As soon as the chisel is raised
out of the cut, the block c is moved by the machinery above described, to
bring the file blank into the proper position for giving the next cut. When
a taper file is to be cut, the rack o, which fits in a groove in the moveable
block c is set, so that its teeth gear into the pinion o¹, and the length of the
rack o is such, that when the broad part of the pile comes under the chisel,
the rack comes out of gear with the pinion o¹. During the working of the
rack o in the pinion o', the worm 05, gearing into the wheel h', gradually
lowers the screwed bush h into the socket of the piece f¹, thereby com-
pressing the spring g', and imparting the requisite additional force to the
blow, which is necessary for cutting teeth of the same depth in the file blank.
As soon as the end of the rack o passes beyond the pinion o¹, the bush h
remains in the place to which it has been brought, and consequently the

page_text: spring g¹ remains at the same tension during the cutting of the parallel part
of the file. When the face of the file has been cut, and the machinery has
been stopped by the self-acting mechanism usually adopted, or by the attendant
throwing the catch box d' out of gear by the handle d³, the moveable
block c is brought back to its original position in the following manner :-The
handle is fast to the hollow screw 7, and the clutch box 7º, which slides on
a key on the shaft l', forms the connection between the shaft and the screw,
consequently when it is requisite to slide the moveable block c by hand, the
attendant disconnects the clutch box 1° from the screw 1, which is then at
liberty to be turned round by hand in either direction without altering the
position of the ratchet wheel ', and the parts by which it is put in motion;
or a friction clutch box may be used instead of the clutch box with catches
as shewn at 1°. When the block c has been brought to the proper position for
commencing the operation of cutting a file blank, or for cross cutting, the
clutch box 1º is again put into gear, and the machine is ready for starting.
The machine above described and shewn in the Drawings, with the com-
pound swivel frame f, f', is adapted to cut the teeth in both directions on
the file, that is to say, when one set of teeth has been cut, the position of
the swivel frame is changed for cutting the teeth in the contrary direction.
The machine may, however, be considerably simplified by using a separate
machine for each cut; when such is the case the driving shaft d is furnished
with a cam d', as shewn in Figure 6, acting direct on the bowl g, which is
supported on a stud passing through the ram g. The tool holder slide i is
connected, as before described, to the key projecting from the ram g; the
22
other parts of the machine may be similar to those above described.
When compressed air is applied to act as a spring for giving the requisite
impetus to the descent of the ram or hammer a piston is attached to the shank
of the ram or hammer g; this piston fits in a cylinder fixed to the top of the
piece f¹, and the capacity of this cylinder may be varied by worm wheel and
gearing, as above described in reference to Figure 5, or other suitable apparatus
may be applied to produce the requisite changes in the force of the blow. This
mode of applying compressed air may be considerably modified according to the
peculiar construction of the machine.
Figure 7 represents my improved mode of supporting half round files during
the operation of cutting. c is the sliding block, and c is a partial cylinder
bearing on the block c, and supported in bearings c. The file to be cut fits in
a recess in the flat space of the block c", which is set so as to bring the
different portions of the surface of the file blank under the cutting tool, by
means of the wedges c'; these wedges are connected to screws furnished with

page_text: hand wheels for slackening them when the block crequires moving for giving
a fresh cut, and for tightening them when the block is set. The block is
graduated, and a pointer is fixed to one of the bearings c for setting the file
blank, by means of the handle c, which fits on the square end of the
block c³.
a
The last part of my Invention, which consists in producing slight irregu-
larity or zig-zag or wave in the teeth of the file, will be clearly understood in
reference to Figures 8 and 9, the former being a side elevation, and the latter
a plan of part of the machine shewn in the foregoing Figures. The moveable
block is made in two parts, the lower part c slides to and fro on the bed b,
and the upper part marked c¹ is connected to the lower part by the fulcrum
stud c², and by the screws c³, which pass through slots in the upper part. To
the bed bis bolted the bracket 62, in which is a stud 63 taking into a waved
slot in the plate c', which is cast with or bolted to the end of the plate c¹.
When the machine is at work the waved slot acting against the fixed stud b³
imparts a slight lateral motion in contrary directions to the plate c', and con-
sequently to the file blank, which is fixed upon it, and this lateral motion
produces a slight irregularity or zig-zag or wave in the teeth of the file, the
object of which will be apparent to persons conversant with the use of files, as
the perfect parallel accuracy in the teeth of machine-made files gives a lateral
tendency to the file when in in use, whereas the slight irregularities, zig-zag, or
wavy position of the teeth in hand-made files counteracts the lateral tendency.
The slight lateral motion in contrary directions may be produced in the manner
shewn and described, or by any other suitable combination of machinery either
in connection with the sliding block or with the cutting tool or chisel.. It will
be evident that the waved slot in the plate c' can be altered in shape, so as to
give more or less motion to the file, and that the plate can be changed when
longer or shorter files are being cut.
In witness whereof, I, the said Francis Preston, have hereunto set my
hand and seal, this Eighteenth day of December, in the year of our
Lord One thousand eight hundred and sixty..
FRANCIS PRESTON. (L.S.)