IMPROVEMENTS IN TOOLS OR MACHINES FOR OPERATING SCREW THREADING TAPS
Year: 1885

page_text: I, ARTHUR WILLIAM LOVELL REDDIE of the Office for Patents 6 Bream's
Buildings Chancery Lane in the County of Middlesex, Patent Agent, do hereby
declare the nature of the invention for IMPROVEMENTS IN TOOLS OR MACHINES
FOR OPERATING SCREW THREADING TAPS, to be as follows
-
This invention relates to a tool or device which may be secured to the spindle of
a drilling machine, lathe or tapping machine and by which a screw, threading tap
may be turned in one direction to tap a hole and then turned in a reverse direction
to back out the tap
In its most approved form the tool or device comprises a chuck which may be
secured upon the rotary spindle of a machine, a tap head or holder which is secured
upon the tap and a tap driver having a cavity receiving within it the tap head or
holder and also having a shank fitting within the chuck, the tap driver being
constructed to engage with the tap head or holder and to turn the latter and its
attached tap in one or other direction to screw in or back out the tap
The tool or
device also comprises a stop which is adjustable upon the tap driver, and may be
set so that the tap will project a predetermined distance beyond it, according to the
length to which it is desired to enter the tap into the hole to be tapped
An important object of the invention is to so construct the chuck and the shank
of the tap driver which is received therein, that the chuck will have a sufficiently
strong engagement with the shank to turn the tap driver and tap until the tap is
entered the distance limited by the stop, and so that after the tap has entered to
the desired distance the chuck will turn on the shank without turning the tap
driver or tap, such further turning of the tap driver and tap being prevented by
the stop abutting up against the work.
To secure the desired result, the shank of the tap driver and the socket of the
chuck which receives said shank are of corresponding polygonal form, and the
chuck 18 slotted or cut lengthwise, so as to form a number of spring fingers or jaws
which engage with the sides of the polygonal shank of the tap driver. The exterior

page_text: of the chuck is screw threaded, and thereon is fitted a nut or screw threaded ring,
which may be adjusted by turning it, lengthwise of the chuck so as to leave a
greater or less length of the spring fingers or jaws free to expand or spread
outwards These spring fingers or jaws grasp the shank of the tap driver with
sufficient strength to enable them to turn the tap driver when exerting only the
force necessary to turn the tap in cutting the thread, but when the further entrance
of the tap is resisted by the stop abutting against the work, the increased resistance
opposed to the turning of the tap will be such that the jaws or fingers of the chuck
will spring outwards and permit the chuck to turn upon the shank of the tap
driver, without turning the tap driver or the tap.
The tap, which is of ordinary form, has secured to its shank, a tap head or holder
which is cylindric in its general form, and which is received within a cylindric
socket in the tap driver This socket is of such depth and so proportioned to the
length of the tap head or holder, that the tap head or holder is capable of length-
wise movement within the socket Upon that portion of the tap head or holder
which fits within the socket of the tap driver, are spiral projections which are
made in the form of sections of a screw thread, and which extend about half the
circumference of the tap-head or holder, and in the cavity of the tap-driver are
pins or projections both above and below that portion of the tap head or holder
which is constructed with spiral or cam-like projections The said pins are
adapted to engage with the upper or lower ends of the spiral or cam-like projections
of the tap head or holder, and to so turn the tap head or holder and its attached
tap, when the chuck and tap driver are rotated in one or other direction, as to
enter or back out the tap
In entering the tap, the upper cross pin or projection in the cavity of the tap
driver engages with the upper ends of the spiral or cam-like projections of the
tap holder, and when the tap has been entered to the required distance and
the chuck turns upon the shank of the tap driver, the chuck and tap driver are
raised and by such movement the upper pin or projection in the tap driver is first
disengaged from the upper ends of the spiral or cam-like projections on the tap
holder, and the lower pin or projection in the tap driver is then brought into
engagement with the lower ends of such spiral or cam-like projections.
By then turning the machine spindle, and the chuck and tap driver in a reverse
direction, the tap head or holder and attached tap will be turned in a direction to
back the tap out of the work
The stop which limits the entering movement of the tap, consists of a stirrup or
bail-like portion through which the tap passes, and which is secured to a ring
or screw-threaded collar adjustable upon the screw threaded exterior of the tap
driver.

page_text: threading Taps.
I, ARTHUR WILLIAM LOVELL REDDIE of the Office for Patents, 6 Bream's
Buildings, Chancery Lane in the County of Middlesex, Patent Agent do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement
-
This invention relates to a tool or device which may be secured to the spindle of
a drilling machine, lathe, or tapping machine, and by which a screw-threading tap
may be turned in one direction to tap a hole, and then turned in a reverse direction
to back out the tap
In its most approved form, the tool or device comprises a chuck which may be
secured upon the rotary spindle of a machine, a tap head or holder which is
secured upon the tap, and a tap driver, having a cavity receiving within it the tap
head or holder, and also having a shank fitting within the chuck, the tap driver
being constructed to engage with the tap head or holder, and to turn the latter and
its attached tap in one or other direction to screw in or back out the tap The
tool or device also comprises a stop which is adjustable upon the tap driver, and
may be set so that the tap will project a predetermined distance beyond it,
according to the length to which it is desired to enter the tap into the hole to be
tapped.
An important object of the invention is to so construct the chuck and the shank
of the tap driver, which is received therein, that the chuck will have a sufficiently
strong engagement with the shank to turn the tap-driver and tap, until the tap is
entered the distance limited by the stop, and so that, after the tap has entered to
the desired distance, the chuck will turn on the shank without turning the tap-
driver or tap, such further turning of the tap-driver and tap being prevented by
the stop abutting up against the work
To secure the desired result, the shank of the tap-driver, and the socket of the
chuck which receives said shank, are of corresponding polygonal form, and the
chuck is slotted or cut lengthwise, so as to form a number of spring fingers or
Jaws, which engage with the sides of the polygonal shank of the tap-driver The
exterior of the chuck is screw threaded, and thereon is fitted a nut or screw-
threaded ring which may be adjusted by turning it lengthwise of the chuck, so as
to leave a greater or less length of the spring fingers or jaws free to expand or
spread outwards These spring fingers or jaws grasp the shank of the tap-driver
with sufficient strength to enable them to turn the tap-driver, when exerting only
the force necessary to turn the tap in cutting the thread, but when the further
entrance of the tap is resisted by the stop abutting against the work, the increased
resistance opposed to the turning of the tap will be such, that the jaws or hingers
of the chuck will spring outwards, and permit the chuck to turn upon the shank of
the tap-driver without turning the tap driver or the tap
The tap, which is of ordinary form, has secured to its shank a tap head or
holder, which is cylindrical in its general form, and which is received within a

page_text: cylindrical socket in the tap-driver This socket 18 of such depth, and so pro-
portioned to the length of the tap-head or holder, that the tap-head or holder 18
capable of lengthwise movement within the socket. Upon that portion of the tap-
head or holder which fits within the socket of the tap driver, are spiral projections,
which are made in the form of sections of a screw thread, and which extend about
half the circumference of the tap-head or holder, and in the cavity of the tap
driver are pins or projections, both above and below that portion of the tap head
or holder which is constructed with spiral or cam-like projections The said pins
are adapted to engage with the upper or lower ends of the spiral or cam-like
projections of the tap-head or holder, and to so turn the tap-head or holder and its
attached tap, when the chuck and tap driver are rotated in one or other direction,
as to enter or back-out the tap
In entering the tap, the upper cross pin or projection in the cavity of the tap-
driver engages with the upper ends of the spiral or cam like projections of the
tap-holder, and when the tap has been entered to the required distance, and the
chuck turns upon the shank of the tap driver, the chuck and tap driver are raised,
and by such movement the upper pin or projection in the tap driver is first
disengaged from the upper ends of the spiral or cam like projections on the tap
holder, and the lower pin or projection in the tap driver is then brought into
engagement with the lower ends of such spiral or cam like projections
By then turning the machine spindle and the chuck and tap-driver in a reverse
direction, the tap-head or holder, and attached tap, will be turned in a direction to
'back the tap out of the work
The stop which limits the entering movement of the tap consists of a stirrup or
bail-like portion, through which the tap passes, and which is secured to a ring or
screw threaded collar adjustable upon the screw threaded exterior of the tap diver
In the accompanying drawing, Fig 1 is a side view of a device embodying the
invention, Fig 2 is an axial section representing the tip-driver as in eng igement
with the tap-head or holder for diving the tap forward, Fig 3 18 a simil ir section
of the tap-driver and parts below it, representing the tap driver as in engagement
with the tap-head or holder backing out the tap, Fig. 4 is a transverse section on
the dotted line wx, Fig 1, and Fig 5 is a similar section on the dotted line y y,
Fig 2.
Similar letters of reference designate corresponding parts in all the Figures.
A designates the chuck, which may be made of steel-It comprises a number of
elastic fingers or spring jaws, a, (here shown as five) forming between them a
polygonal socket. Any number of jaws may be provided to form a polygonal
socket having any desired number of sides
The chuck here shown has a shank A¹, which is intended to fit into the spindle
of a drilling machine, lathe, or tapping machine, and which is detachably secured
to the chuck by being screwed thereinto, a safety pin b, being inserted through
them to prevent the accidental turning of the chuck on the shank
When the shank is detachably secured to the chuck, provision is afforded for
using the chuck with any one of a number of shanks htted to the spindles of
different machines, but when the chuck is to be used with only one machine, the
shank A¹ may be formed integral with, or permanently connected with the
chuck
B designates the tap-driver, which consists of a cylindrical block or piece having
projecting from its upper end a shank B¹, which is polygonal to ht the polygonal
socket of the chuck As here shown, the chuck A, 18 chambered out above its
lower portion, and the shank B₁ of the tap-driver is held against detachment
therefrom by a washer or cap c secured upon its upper end by a sciew c¹-In
assembling the parts, the shank B¹ 18 inserted into the chuck A, before the chuck-
shank A¹ 18 screwed thereinto, and a screw driver may be inserted down through
the chuck to insert the screw cl
The exterior of the split chuck A 18 screw-threaded, and thereon is fitted a nut
or collar C, which may be adjusted up and down thereon, to vary the length of

page_text: the spring fingers or jaws a, which are left free to spring outwards, and so
regulate the firmness with which the chuck holds the shank B₁ of the tap-driver B
When the ring or collar C is screwed down near the lower end of the thread on
the chuck, the chuck will drive the tap very strongly, and it will require a great
resistance to cause the fingers a to spring, as is necessary, to allow the chuck to
turn on the shank B'. When the ring or collar C is adjusted to a position near
the upper end of the screw thread, the spring fingers, a, will yield much more
readily, and a much less resistance will suffice to arrest the tap and cause the
chuck to turn idly on the shank B¹
D designates a tap of ordinary form, and which is secured firmly in a head or
tap-holder E. This head or holder has upon its exterior, spiral projections, d,
which form sections of screw threads, and which externally fit a cylindrical
cavity in the tap-driver B-The lower end of the tap driver B is closed by a screw
cap B which, as shown, has a milled edge, whereby it may be readily turned by
hand, and through this cap the smaller portion of the tap head or holder E works
The adjustable stop for the tap, as here shown, consists of a bail or stirrup F,
having at the lower portion a hole or opening f, through which the tap D works,
and having its upper portions secured to a ring or band G, which is screwed upon
the exterior of the tap-driver B, and held in any desired position thereon by a
Jamb nut G By adjusting the band or ring, and then securing it in place by the
lock nut, the stop F may be adjusted or set so as to permit the tap D to enter the
work to any desired depth, before it is arrested by the stop bringing up against
the work
In the upper part of the cavity e, in the tap-driver B, is a cross-pin g, and
projecting inwards into the cavity from opposite sides, and at the lower part
thereof, are pins h, forming projections which extend to the exterior of the head
or holder E-The pin g is adapted to engage with the shoulders or stops * formed
by the ends of the spiral projections, which are presented uppermost when the
duver B, 18 turned in one direction, and when the driver is raised relatively to
the tap head or holder E, and turned in a reverse direction, the pins h engage with
the shoulders or stops &, formed by the lower ends of the projections
The operation of the device is as follows -The stop F, having been adjusted to
the proper position, the chuck and tap-drvier A, B, are turned, and the pin g,
engaging with the shoulders or stops *, the tap is turned to drive it forward
through the work-When the stop F reaches the work, it bears thereon, and
thereby increases the frictional resistance to the turning of the tap, to such a
degree that the chuck A will spring, and turn on the shank A-The direction of
rotation of the spindle and chuck are thereupon reversed, and as the spindle moves
backwards, the pins h engage the shoulders or stops of the tap-head or holder,
and so back the tap out.
The connection between the tap driver B, and tap head or holder, is such, that
the ping will be entirely disengaged from the shoulders *, before the pins h
engage the shoulders
and vice versa and compensates for any differences
between the feed of the spindle in which the device is carried, and the feed of the
tap due to its pitch. In some cases, a chuck A, of the kind described, might be
used to receive directly the shank of a tap, and so turn the same until the
resistance became such as to cause the chuck to turn on the shank by reason of
the yielding of the spring fingers.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondents, I declare that what I claim is
1. The combination with a chuck to be secured to a rotating spindle, and having
a polygonal socket formed by spring jaws or elastic fingers, of a polygonal shank
through which a tap is to be turned, fitting in, and to be driven by the said chuck,
and, preferably, also a screw threaded ring or collar adjustable upon the exterior

page_text: of the chuck, for increasing or diminishing the elasticity of such spring jaws or
elastic fingers, as heremabove described
2 The combination with a chuck having a polygonal socket and spring fingers
or jaws, of a tap driver having a polygonal shank fitting said socket, and also
having a cylindrical socket and a tap head or holder attached to the shank of the
tap, and fitting within, and driven by the tap driver, as hereinabove described
3 The combination with a tap driver having a polygonal shank and a cylindrical
socket, in which are upper and lower cross pins or projections, of a tap head or
holder attached to the shank of the tap, fitting within the socket of the tap driver,
and provided with spiral or cam like projections, with the upper and lower ends
of which the cross pins or projections of the tap driver are engaged to enter or
back out the tap, as hereinabove described.
4 The combination with a tap driver having a polygonal shank and cylindrical
socket, and a tap head or holder fitting within and diven by the tap driver, as
described, of a screw threaded collar fitting the exterior of the tap driver, and the
stirrup or piece secured to and projecting from said collar, and forming a stop to
limit the entrance of the tap, as hereinabove described.
DAL 1L
1000