IMPROVEMENTS IN MACHINERY OR APPARATUS FOR CUTTING SCREW THREADS
Year: 1868

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN MACHINERY OR APPARATUS FOR CUTTING SCREW
THREADS." A communication from abroad by Paul Henri Ferdinand
De Résener, of Paris, in the Empire of France, Engineer.
Sealed the 6th April 1869, and dated the 7th November 1868.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 7th November 1868.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN MACHINERY OR APPARATUS FOR CUTTING
SCREW THREADS," a communication from abroad by Paul Henri Ferdinand
De Résener, of Paris, in the Empire of France, Engineer.
This Invention relates to certain peculiar constructions and arrange-
.ments of machinery or apparatus to be worked eitlier by power or by
hand for cutting screw threads, whereby any variety of form of screws
T

page_text: may be cut in the same machine by a simple adjustment, whilst the
machine itself is cheaper and much more simple than those hitherto
employed for screw cutting.
The essential feature of novelty in this Invention is the employment
of a travelling inclined plane, the angle of the incline being adjustable
by means of a screw and adjusting nuts for the purpose of imparting the
necessary longitudinal traverse to the screw blank or to the cutter, such
travelling incline being moved forward in a guide by means of a pinion
in gear with a rack on the slide which carries the incline. This actuating
pinion derives its motion from the mechanism which rotates the screw
blank or cutter, as the case may be, so that the rate of motion of the
incline along its guide is always in proportion to the speed of rotation of
the screw blank or of the cutter, and hence a spiral or screw-thread will
be produced upon the blank. By varying the angle of the incline, or by
altering the speed of rotation of the screw blank or of the cutter, or by
combining both these changes, it is obvious that screws of any desired
pitch or number of threads may be cut without the necessity for
employing the numerous change wheels requisite in ordinary screw-
cutting lathes.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 7th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Mid-
dlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of November, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or 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,

page_text: 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 OR APPARATUS FOR CUTTING SCREW THREADS." a
communication from abroad by Paul Henri Ferdinand De Reséner,
of Paris, in the Empire of France, Engineer, upon the condition
(amongst others) that I, the said John Henry Johnson, my executors or
administrators, by an instrument in writing under my hand and seal,
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 John Henry Johnson, 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, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon, that is
to say-
The said Invention relates to certain peculiar constructions and
arrangements of machinery or apparatus to be worked either by power
or by hand for cutting screw threads, whereby any variety of form of
screws may be cut in the same machine by a simple adjustment, whilst
the machine itself is cheaper and much more simple than those hitherto
employed for screw cutting.
The essential feature of novelty in this Invention is the employment
of a travelling inclined plane, the angle of the incline being adjustable
by means of a screw and adjusting nuts for the purpose of imparting the
necessary longitudinal traverse to the screw blank or to the cutter, sucli
travelling incline being moved forward in a guide by means of a pinion
in gear with a rack on the slide which carries the incline. This actuating
pinion drives its motion from the mechanism which rotates the screw
blank or cutter, as the case may be, so that the rate of motion of the
incline along its guide is always in proportion to the speed of rotation of
the screw blank or of the cutter, and hence a spiral or screw thread will
be produced upon the blank. By varying the angle of the incline, or by
altering the speed of rotation of the screw blank or of the cutter, or by
combining both these changes, it is obvious that screws of any desired
pitch or number of threads may be cut without the necessity of

page_text: employing the numerous change wheels requisite in ordinary screw-
cutting lathes.
And in order that the said Invention may be fully understood I shalt
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheets of Drawings, the
same letters of reference indicating corresponding parts in all the
corresponding Figures.
Figure 1 of the Drawings is an external elevation and partial section,
and Figure 2 a corresponding plan of a lathe, to which the inclined plane is
adapted for screw-cutting purposes; Figure 3 is a transverse vertical section
taken through the centre of the slide rest along the line 1-2, and looking
in the direction of the arrow (Figure 2); Figure 4 is an end elevation of
the driving gear; Figure 5 is a transverse section taken along the line
3-4 (Figure 1); and Figures 6 and 7 are detail views, shewing the
adjustable inclined plane.
The machine is composed of a frame A carrying the whole of the
mechanism, a slide rest B, the back centre C, and the adjustable inclined
plane D. The main shaft E, which may be turned by hand by means of
the handle e carries the gearing G and a chuck H. An intermediate
shaft I carrying corresponding cone gearing G₁ actuates the lower
spindle J through the intervention of the wheels i and j. On the
spindle J there is mounted a pinion c³, which gears with one of two
racks c, c', in connection with the adjustable incline D. The adjustable
incline (Figures 6 and 7) consists of a U-shaped bar hinged at d into
another U-shaped iron bar or guide D', carrying the racks c, c', on its
upper and under surface. At the opposite end to the hinge these two
parts D and D' are connected together by a screw o fixed at o¹, and
passing through the adjustable incline D. The screw o is provided on
cach side of the incline with a milled headed nut, so that the distance
between the plane D and the bar D' may be increased or diminished as
required. The inclined plane thus arranged is mounted in a guide A¹
(Figure 1) formed in the frame A, so that one of the racks c' will be in
gear with the pinion fast on the spindle J. The inclined plane D acts
on the slide rest B in the following manner-The slide rest has a socket
cast upon it, in which is fitted the shank of a roller carrier L, the roller
Z of which is in contact with the inclined plane, as the position of the
roller has to be altered for each different pitch of screw. The carrier L
is made adjustable and is maintained in its place by a gripping ring

page_text: provided with a tail piece having a screw thread formed on it, which is
secured by means of the hand nut N. The counterweight N¹ tends
constantly to draw the roller carrier L with the slide rest B in such a
direction as that the roller may be always in contact with the face of
the inclined plane D. A small intervening space separates the two sets
of gearing G and G', which can only operate through the intervention
of the intermediate pinion g mounted in an adjustable arm or carrier g¹,
shown clearly in Figure 4, which may be moved vertically and hori-
zontally as required. On rotating the handle e two wheels of the sets
of gearing G and G' transmit motion to the spindle J, which by means
of the pinion c actuates one of the racks c, c', which causes the bar D'
to move in the direction of the arrow y (Figure 2), consequently the
inclined plane D (the angle of which in relation to the bar D' has been
adjusted) presses the roller and with it the slide rest B, the tool b of
which acts on the screw blank secured between the centres of the
machine, as in an ordinary lathe. As the relative speeds of the shaft E
and the rack c are the same, it follows that if the angle or inclination of
the inclined plane D be varied by means of the adjusting screw o, the
traverse of the guide D' being also increased or diminished, the spirals
formed by the cutting tool will be at greater or less intervals and con-
sequently the pitch of the screw thread will be varied. The two sets of
gearing G and G serve to change the relative speeds of the shaft E and
the rack c, in order to cut screws of a given number of threads.
order to cut screw threads in the reverse direction it is simply necessary
to reverse the position of the bar D', when the rack c will then be
brought into gear with the pinion of the shaft J, and to change the
direction of rotation of the shaft E. When cutting double or multiple
threaded screws one thread is first cut, after which the position of the
pin h in the plate or chuck H, against which the dog" t presses, is
changed in order to cut a second thread, and again for a third, and
finally a fourth thread; in each case of course the inclined plane D
with its guide D' is brought back to its starting point again.
In
Sheet 2 of the Drawings shews the application of the adjustable
inclined plane to a portable tool or screw stock, which may also be
employed as a universal screw-cutting machine by fixing it in a vice or
otherwise attaching it to a work bench.
Figure 8 is a longitudinal vertical section of the portable tool taken
partly along the line 7-8, (Figure 11) and partly along the line 9-10, of

page_text: the plan (Figure 9). Figure 3 is a plan and partial section taken along the
line 11-12; Figure 10 is a transverse section intended to shew the mode
of actuating the guide of the inclined plane; and Figure 11 is a plan of
the top part of the machine. It will be observed that the same arrange-
ment of inclined plane D, as that described with reference to the pre-
ceding machine, is employed in this description of tool, and that the same
letters indicate corresponding parts in both arrangements. The blank
to be screwed is placed vertically in the centre of the cross piece L',
which is connected by the rods ' to the roller carrier L disposed under
the inclined plane D; the object of the springs r is to draw the roller
upwards in order to keep it in contact with the inclined plane D, the
motion of which causes the descent of the screw blank, which is firmly
secured in the cross piece L' by the screw v. The cutter b is mounted
on the body of the screw stock H so as to be capable of receding under
the action of a helical spring; the screw stock is provided with dies
which simply serve to centre the screw blank to be operated upon, and
it has cast or forged upon it a pinion h, which gears with the wheel G
keyed on to the upper end of the spindle I. This spindle carries a
pinion i, which by the intervention of the wheel j fixed on the spindle J
actuates the pinion c gearing with either the rack c¹ or c, as the case
may be, of the guide D' of the inclined plane. It follows from this
combination that one turning the screw stock by hand rotatory motion
is imparted through the gearing above described to one of the racks in
order to cause the inclined plane D to move forward; as the inclined
plane advances the cross piece L' descends, and the cutter b cuts the
spirals to a greater or less pitch, as may be required. The screw stock
turns round a socket cast on the frame A which serves as an axis, and
in order to permit its displacement during the course of the operation a
small screws is provided which enters an annular groove formed around
the axis, as shewn in Figure 8. The methods of regulating the position
of the inclined plane in relation to its guide D' are similar to those
employed in the screw-cutting machine first described. The frame is
reduced in width at its lower part so as to form shoulders X, which rest
on the jaws of the vice in which the whole machine may be placed.
The adjustable inclined plane may obviously be applied to other
descriptions of screw-cutting machines or tools. The blank to be screwed
may be rotated and the tool or cutter caused to traverse by the action
of the adjustable incline plane, as herein-before described, or the tool or

page_text: cutter may be rotated and the screw blank caused to advance, or the tool
or cutter may be caused to rotate and to advance whilst the screw blank
remains stationary, or the tool or cutter may be fixed and the screw.
blank caused to rotate and advance. If desired a lever carrying the tool
or cutter may be substituted for the slide, the lever working on
fulcrum at one end and having pressure applied to the other and to
cause the tool or cutter to bite.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured
to me by the herein-before in part recited Letters Patent is, the applica-
tion and use to and in the cutting of screw threads of all pitches of
an adjustable incline, operating substantially as herein-before described.
In witness whereof, I, the said John Henry Jolinson, have to this
my Specification set my hand and seal, the Seventh day of May,
One thousand eight hundred and sixty-nine.
J. HENRY JOHNSON. (L.S.)