IMPROVEMENTS IN SCREW CUTTING APPARATUS.
Year: 1879

page_text: LETTERS PATENT to William John McCormack, of Paignton, in the County
of Devon, for the Invention of "IMPROVEMENTS IN SCREW CUTTING
APPARATUS.
"
Sealed the 29th August 1879, and dated the 30th May 1879.
PROVISIONAL SPECIFICATION left by the said William John McCormack
at the Office of the Commissioners of Patents on the 30th May 1879.
WILLIAM JOHN MCCORMACK, of Paignton, in the County of Devon.
MENTS IN SCREW CUTTING APPARATUS."
"IMPROVE-
This Invention relates to improvements in the construction of stocks and dies
and of expanding taps, chiefly applicable for cutting screw threads on pipes, and for
tapping pipe sockets and unions, and for opening and enlarging the threads in pipe
sockets, and my improved apparatus or tackle being very portable is especially
useful for jobbing purposes.
In carrying out my Invention the stock or die plate is formed with a central
hole into which open four holes or openings passing edgeways through the stock
from the ends and in a nearly radial direction with the centre of the hole in the
stock. The dies or bits are provided with threads or teeth at both ends, so that
they may be reversed, and are preferably formed of round steel, which is a great
advantage, the said dies pass into the herein before described radial holes, and when
the dies are made of round metal the said holes are formed with a key and the dies
with a keyway, so the dies are held perfectly firm; the dies can however be made
of other section of steel, the radial holes in the stock corresponding in shape, and in
this case no key or key way will be required. Each end of the stock or dio plate
is formed with a screw theaded projection on which screws a collar or ferrule by
turning which by means of a suitable key the dies are tightened or released, a loose
collar of brass or other suitable metal being placed between the ends of the dies and
the screw ferrule.
Into the ends of the said projections of the stock screw the handles for operating
the apparatus, and these handles being removeable render the apparatus very
portable. The placing of the dies radially and their being reversible allow of

page_text: screwing four different sized pipes with each tool and without the aid of other
dies.
My improved screw cutting tap is either taper or plug, and expanding, and
consists of a cylindrical stock or mandril with four longitudinal slots tapered at
their lower ends; in these slots are placed the cutting bits or taps which are also
inclined or tapered on their lower ends at their underside; the upper ends of the
cutting bits are slotted to receive a screw ring which screws on a thread on the
upper end of the stock or mandril, so that by turning the said screw ring the cutting
bits are expanded by being moved outwards or contracted by being moved inwards
according to the direction in which the ring is turned. By using a slotted collar in
place of the mandril the apparatus can be made to screw the outside of light brass
tubes.
Or the cutting bits for the taps only may be operated by a central screw on a
core or plug in the mandril.
The tap is formed with the usual square head and may be as easily sharpened as
any ordinary screw tool.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William John McCormack in the Great Seal Patent Office on the
29th November 1879.
WILLIAM JOHN MCCORMACK, of Paignton, in the County of Devon.
MENTS IN SCREW CUTTING APPARATUS."
"IMPROVE-
This Invention relates to improvements in the construction of stocks and dies
and of expanding taps, chiefly applicable for cutting screw threads on pipes, and for
tapping pipe sockets and unions, and for opening and enlarging the threads in pipe
sockets, and my improved apparatus or tackle being very portable is especially
useful for jobbing purposes, and the object of my Invention is to simplify the con-
struction and reduce the cost of such apparatus, also to so construct the apparatus
as to render it suitable for screw threading pipes of different sizes instead of it
being necessary as at present to employ separate dies for each size of pipe.
But to make my Invention better understood I will proceed to describe the same
by reference to the accompanying Drawing, in which Figure 1, Sheet 1, is a side
view partly in section of my improved stock and dies; Figure 2, Sheet I, plan of
same partly in horizontal section; Figures 3 and 4, Sheet 1, side elevation and
longitudinal section of my improved screw cutting tap; and Figures 5 and 6,
Sheet 1, end views of the same; Figures 7 and 8, Sheet 1, side elevation and
longitudinal section of a modified construction of expanding tap; Figures 9 and 10,
Sheet 1, end views of the same; Figures 11 and 12, Sheet 2, side elevation and plan
(on a smaller scale) of my improved screw stock, similar to that shewn in Figures 1
and 2, Sheet 1, but fitted with an attachment which I prefer employing when screw
threading light (that is to say thin) pipes; Figure 13 is a detached vertical section

page_text: of this attachment, and Figures 14 and 15 shew an elevation and vertical section
of a simplified construction of the attachment. Similar letters in all the Figures
represent similar parts.
In Figures 1 and 2, Sheet 1, and 11 and 12, Sheet 2, A represents the stock or
die plate which is formed with a central hole a into which open four horizontal
holes or openings passing edgeways through the stock A from the ends, and in a
nearly radial direction with the centro of the hole in the stock, as shewn in Figure
2, Sheet 1; B, B, are the dies or bits which are provided with threads or teeth at
both ends, so that they may be reversed, and they are preferably formed of round
steel instead of square or other section of steel as hitherto. The said dies B pass
into the herein before described radial holes, and when the dies B are made of round
metal the said holes are provided with a key C and the dies with a key way C¹, so
that the dies B are held perfectly firm; the dies can however be made of other
section of steel, the radial holes in the stock corresponding in shape, and in this
case no key or key way will be required.
Each end of the stock or die plate A is formed with a screw threaded projection D
on which screws a collar or ferrule E, by turning which by means of a suitable key
the dies B are tightened or released, a loose collar F of brass or other suitable metal
being placed between the ends of the dies and the screw ferrule, as shown. Into the
ends of the said projections D of the stock are screwed the handles G for operating
the apparatus, and these handles being removeable render the apparatus very
portable. The placing of the dies radially, or nearly so, enables them to be adjusted
to any circle, and their being reversible allows of screwing four or more different
sized pipes with each tool and without the necessity of employing other dies, it
being understood that the pitch of the thread is the same for pipes of different
diameters. When screwing brass tubes of the larger sizes, but of thin metal, I
employ the moveable attachment or device shewn in Figures 11, 12, and 13, Sheet
2, the object of which is, firstly, to support the tube against the action of the dies;
and secondly, to prevent the dies tilting out of their proper position when com-
mencing to cut the thread. This attachment consists of a saddle plate H, through
the centre of which passes a hollow expanding screw threaded tubular core I tapered
inside at its lower part, as shewn in Figure 13, and slotted at the lower_end, as
shewn in Figure 11. In the top of the hollow core I works a set screw K which
when turned downwards forces down the conical_pointed pin e, whereby an
expanding movement of the lower end of the core I is obtained. On the lower
end of the core I is placed a slotted moveable collar J of box-wood or other suitable
material. Each end of the saddle plate H is slotted (or perforated) at b, b, so as to
allow of its being fixed by the set screws e, e, to the stock A, as shewn in Figures
11 and 12, Sheet 2, the attachment being fixed as hereinbefore described and shewn
in Figures 11 and 12, Sheet 2; if it is required to screw thread a pipe, the slotted
collar Jis passed into the tube or pipe d to be screwed; then by turning the
screw K. the core I will be expanded as herein before described, and will expand
the collar J tightly in the tube d to be screwed. The thread of the core I and
saddle H being of the same pitch as the ordinary gas pipe thread it follows
that if the screw stock be turned it will carry down with it the dies in a steady
and regular manner, the core I acting as a fixed guide on which the saddle plate,
and consequently the screw stock, move or turn, thus ensuring true threads on tubes
of large diameter.
In the modified construction of device shewn in Figures 13 and 14 I employ a
solid screw headed core R tapered at its lower end and screwing into a taper female
screw in the slotted collar J. It will be seen that by turning downwards the core
R the collar will be expanded.
My improved screw cutting tap, shewn in Figures 7, 8, 9, and 10, Sheet 1, may
be used either as a taper tap or may be expanded so as to form a parallel plug tap,
and is constructed of a cylindrical stock or inandril L with four or other number of
longitudinal slots (shewn in the end view, Figure 10) tapered at their lower ends;
in these slots are placed the cutting bits or taps M, which are also inclined or

page_text: tapered on their lower ends at their underside, as seen in Figure 8, the upper
ends of the cutting bits are slotted at n to receive a screw ring N which screws
on a thread O on the upper end of the stock or mandril; when the cutting bits M
are resting solid or in their normal position, as shewn in the Figures, but by
turning the said screw ring N the cutting bits M. will be moved in the direction of
the arrow and will be expanded in consequence of the inclined end of the mandril
acting against the tapered ends of the bits M, whereby the tap may be enlarged
and converted into a parallel or plug tap, thus avoiding the necessity of having
more than one tap for each size of tube, and the expanding movement being under
the control of the operator, the great force necessary in using solid taps of large
size is done away with. It will be understood that by using a slotted collar in
place of the mandril, the apparatus can be made to screw the outside of light brass
tubes.
A modification of this construction of screw cutting tap is shewn in Figures 3, 4,
5, and 6, Sheet 1, in which the cutting bits M for taps may be operated by a
central screw P on a core or plug O in the mandril, Figures 3, 4, 5, and 6, the said
core or plug being moved forwards or backwards in the mandril L by turning the
screw cap L¹.
The tap is formed with the usual square head and may be as easily sharpened as
any ordinary screw stool.
t
Having thus described my said Invention, and the manner of performing the
same, I wish it to be understood that I do not confine myself to the precise details
herein laid down and shewn in the Drawing, as the same may be varied
departing from the peculiar character of my Invention, but what I do claim. 1,
Firstly. The general arrangement and construction of the improved screw stock
or die plate, as heroin before described and represented in Figures 1 and 2, Sheet 1 of
the accompanying Drawings, or any mere modification thereof.
Secondly. The construction and employment in combination with screw stocks
and dies of the device or attachment shewn in Figures 11, 12, and 13, Sheet 2 of
the Drawings, arranged and operating substantially in the manner and for the
purposes hereinbefore described, or the modification thereof shewn in Figures 14
and 15, Sheet 2 of the Drawings.
Thirdly. I claim the use of dies made of round steel and provided with a key
way, as hereinbefore described and represented in the accompanying Drawings.
Fourthly. The construction, arrangement, and employment of combined plug and
taper taps with expanding movement, as hereinbefore described and represented in
Figures 3, 4, 5, 6, 7, 8, 9, and 10, Sheet 1 of the Drawings.
In witness whereof, I, the said William John McCormack, have hereunto set
my hand and seal, this Twenty fifth day of November, in the year of our
Lord One thousand eight hundred and seventy nine.
UTT TTAM TOWN MCCORMACK
Tal