IMPROVEMENTS IN SCREW TAPS, MORE ESPECIALLY DESIGNED FOR CUTTING THREADS IN THE FITTINGS AND CONNECTIONS FOR GAS, STEAM, AND WATER PIPES
Year: 1865

page_text: LETTERS PATENT to William Foster, of New. York, United States, but
now of No. 12, Southampton Buildings, Chancery Lane, in the County
of Middlesex, Manufacturer, for the Invention of "IMPROVEMENTS IN
SCREW TAPS, MORE ESPECIALLY DESIGNED FOR CUTTING THREADS IN THE
FITTINGS AND CONNECTIONS FOR GAS, STEAM, AND WATER PIPES."
Sealed the 13th April 1865, and dated the 28th January 1865.
PROVISIONAL SPECIFICATION left by the said William Foster at the:
Office of the Commissioners of Patents, with his Petition, on the 28th.
January 1865.
I, WILLIAM FOSTER, of New York, United States, but now of No. 12,
Southampton Buildings, Chancery Lane, in the County of Middlesex, Manu-
facturer, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN SCREW TAPS, MORE ESPECIALLY DESIGNED FOR CUTTING THREADS IN THE FITTINGS
AND CONNECTIONS FOR GAS, STEAM, AND WATER PIPES," to be as follows:-
This Invention consists in so constructing and arranging the parts that the
cutters may be withdrawn from their work without reversing or stopping the
tap or machine in which said tap is used. In the lower part of the stock
are formed two or more grooves converging downward; in these grooves

page_text: are placed cutters which are kept from moving laterally by means of a pro-
jection upon each side thereof passing into a recess formed on the sides of
the grooves, and they are connected at their upper ends to a collar around the
stock, and thus held in position. This collar is loose on the stock, but is kept
from falling down by means of a pin passing through the stock and projecting
on both sides into a slot formed in the collar. These slots extend each about
one-fourth around the collar, and are so shaped that by turning said collar
the cutters which are attached thereto are raised or lowered as may be
desired. When the pins are at the lower part of the slot the cutters are in
position for working. To keep the cutters in place when at work the lower
part of the slot is made horizontal,. the remainder being inclined upward,
forming with the lower part an obtuse angle. When the cutters have com-
pleted their work the collar is held by means of handles fixed for convenience
on both sides thereof, the spindle continuing to rotate moves the pins
along said grooves, and consequently the collar is lowered on the stock and
forces the cutters down the converging grooves; by this means the cutters
are set free from the thread of the screw and readily withdrawn by turning
the collar until the pin is again brought to the lower part of the groove,
when the cutters are in the proper position to form another thread.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Foster in the Great Seal Patent Office on the 20th
July 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, WILLIAM
FOSTER, of New York, United States, but now of No. 12, Southampton
Buildings, Chancery Lane, in the County of Middlesex, Manufacturer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenth-eighth day of January, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Foster, Her special licence that I, the said William Foster, my
executors, administrators, and assigns, or such others as I, the said William
Foster, 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

page_text: Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN SCREW
TAPS, MORE ESPECIALLY DESIGNED FOR CUTTING THREADS IN THE FITTINGS AND
CONNECTIONS FOR GAS, STEAM, AND WATER PIPES," upon the condition (amongst
others) that I, the said William Foster, my executors or administrators, 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 William Foster, 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 fol-
lowing statement thereof, that is to say :-
This Invention consists in so constructing and arranging the parts that the
cutters may be withdrawn from their work without reversing
or stopping the
tap or machine in which said tap is used. In the lower part of the stock
are formed two or more grooves converging downwards; in these grooves
are placed cutters which are kept from moving laterally by means of a pro-
jection upon each side thereof passing into a recess formed on the sides of
the grooves, and they are connected at their upper ends to a collar around
the stock, and thus held in position. This collar is loose on the stock, but is
kept from falling down by means of a pin passing through the stock and pro-
jecting on both sides into a slot formed in the collar. These slots extend
each about one-fourth around the collar, and are so shaped that by turning
said collar the cutters which are attached thereto are raised or lowered as may
be desired. When the pins are at the lower part of the slot the cutters are
in position for working. To keep the cutters in place when at work the
lower part of the slot is made horizontal, the remainder being inclined upward
and forming with the lower part an obtuse angle. When the cutters have
completed their work the collar is held by means of handles fixed for con-
venience on both sides thereof, and the spindle continuing to rotate moves
the pins along the said grooves, and consequently the collar is lowered on
the stock and forces the cutters down the converging grooves; by this
means the cutters are set free from the thread of the screw and readily with-
drawn by turning the collar until the pin is again brought to the lower
part of the groove, when the cutters are in the proper position to form another
thread.
Having thus stated the nature of my Invention, I will proceed to describe
more fully the manner of performing the same.

page_text: Figure 1 shows a side view, and Figure 2 a longitudinal section, of a screw
tap constructed in the manner above described, this being the manner in
which I prefer to construct a screw tap in carrying out my Invention. A is
the stock of the tap turned to the desired shape; in the lower part of the.
stock four grooves are formed; the form of these grooves is seen in the
sectional view, Figure 2, and in the end view of the screw tap at Figure 3;
each of the grooves receives one of the cutters C, the cutters being able to
slide up or down in the grooves as required; the bottom of each groove is
undercut, as shown at Figure 3, and the cutters are formed to fit them, so
that the cutters are retained in the grooves. Around the upper part of the
stock is a collar D; this collar is loose on the stock, but is retained from
slipping off it by pins F, F, which project from the stock and enter slots
formed on each side of the collar. A portion of each of these slots is inclined,
so that when the collar is turned the collar is caused to move endwise along
the stock. Around the interior of the collar is formed a slot, and at the
upper end of each cutter is a projection E, which is received in the slot, thus
as the collar moves endwise along the stock the cutters are caused to move
along with it, and as the grooves in which the cutters slide incline towards
each other the cutters are moved outwards or towards each other according
to the direction in which the collar is moved. When the cutters are in posi-
tion for working the pins F are at the lower ends of the slots, and these ends
of the slots are made horizontal in order that when the cutters are at work
they may be securely held in their place. When the tap has gone the desired
distance or depth into the work that is being tapped, the handles H, H,
which project from the collar are held (by the hands of the person attending
the machine to which the screw tap is applied) so as to stop the collar from
rotating, or the collar may be otherwise retained until the pins F, which are
carried forward by the rotation of the stock A, have moved to the opposite
ends of the slots in the collar, the cutters are thus moved inwards towards
each other, when the tap is easily withdrawn. If the handles H, H, are
then again taken hold of and caused to rotate more rapidly than the tap, the
cutters will again be brought into position for tapping another hole without
stopping or reversing the tap or machine in which such tap is used. By
thus constructing screw taps much time will be saved in tapping holes, as the
tap can be withdrawn as soon as its work is completed in place of requiring
the same number of revolutions to take it out of its work that it takes to do
it; the cutters of the tap can also be made harder, and thus wear longer by

page_text: reason of their being no reverse motion, by which the cutting points of taps
constructed as heretofore are liable to be broken off. There is also less
wear and tear in machines to which cutters constructed as above described
are applied, as there is no sudden changing or reversing of the motion of the
machine.
In witness whereof, I, the said William Foster, have bereunto set my
hand and seal, this Fifteenth day of April, in the year of our Lord
One thousand eight hundred and sixty-five.
WILLIAM FOSTER. (L.S.)