Improvements in Drill-chucks.
Year: 1891

page_text: Date of Application, 7th July, 1891-Accepted, 8th Aug., 1891
COMPLETE SPECIFICATION.
Improvements in Drill-chucks.
I, CHARLES THURBER PRATT, of Clayville, in the County of Oneida, State of
New York, United States of America, Machinist, 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:-
My invention relates to improvements on the drill chuck shown and described in
my application for Letters Patent of Great Britain and Ireland, numbered, 5614,
and dated April 1st 1891. The said chuck contained a slotted piece which
oscillated and moved to and fro in a chamber in the body of the chuck, and which
slotted piece engaged with the end of a drill stock for the purpose of taking the
strain of rotating the drill off the teeth of the chuck-jaws. But the chamber in
said chuck necessarily had a lateral chamber or passage which could not be formed
at the same operation as the rest of the chuck, but required a separate operation
thereby adding to the cost of manufacture.
My present invention relates to means for doing away with said lateral passage,
and so forming the chamber in the chuck, that the hole can be made at one
operation, thereby cheapening the cost. In my present invention, the chamber in
the chuck for the slotted piece, which I now term an "equalizing driver," is simply
a cylindrical hole, which is sunk by forging or boring into the chuck body from the
rear face thereof, and also serves to fix the chuck on the arbor, by which the chuck
is secured in a lathe. The driver is a cylindrical piece of metal of smaller diameter
than the hole in the chuck, so that the driver can play from side to side in the hole,
and the driver has a slot in its front face to receive the end of the drill. The
driver is revolved by being engaged on the end of the arbor, or by means of a pin
which is driven through the chuck, and passes with loose fit through a hole in the
driver. Thus the driver revolves the drill, and relieves the jaws of the chuck from
strain, and also by its lateral play, adjusts itself to the inequalities in the form of
the drill stock and end.
Moreover, experience shows that the jaws of drill chucks acquire a tendency to
tilt when they are closed on a drill stock, and to act as wedges to force apart the
walls of the chuck. To prevent this, I provide face plates for the chucks, which
face plates have segments of circular ribs in their inner face, between the centre
and circumference thereof, and these ribs enter the corresponding grooves in the
front face of the chuck, and thereby prevent the spreading of the walls of the
chuck.
Referring now to the drawings which accompany the Specification to aid in
the description:
Fig. 1 is an elevation of the front end of the chuck with the face plate on.
Fig. 2 is an elevation of the same, but with the face plate off.
Fig. 3 is a perspective view of the face plate.
Fig. 4 is an elevation and section on the line y. y. of Fig. 5.
Fig. 5 is a side elevation of the chuck and face plate.
Fig. 6 is section on the line a. c. of Fig. 1.
Fig. 7 is a longitudinal section on a plane perpendicular to the plane of Fig. 6.
Fig. 8 presents views of the driver and arbor, showing respectively the front face
and the rear face of the driver, and the front end of the arbor.
Fig. 9 shows respectively the under side, the toothed face, and the upper side of
a jaw.
Fig. 10 shows respectively a side and an end elevation of a drill.
Figs. 11, 12, and 13 are views of a modification of the chuck wherein a pin passes
through the chuck and through the driver; Fig. 11 being a longitudinal section

page_text: on the same prane as ig. v, and being a long
plane as Fig. 7.
Fig. 131shows details of the driver..
The lettering is the same throughout the several views.
DA DA10300
A is a drill chuck, which is preferably formed of 'steel, and is cylindrical in shape,
and with a rear part, B, of smaller diameter than the part, A, and said part B, is
"bored out, or otherwise fashioned with an axial chamber, b.
Said chamber b, is preferably circular in cross section, and enters a considerable
distance into the chuck A, and usually a little beyond the junction of aforesaid
parts A and B, as shown in Figs. 6 and 7. At its innermost end, said chamber B,
connects with the opening, C, which extends forward to the front face, a, of said
chuck A.
Said opening C, is formed with parallel side walls, c, c, (Figs. 6 & 7) and in
said opening, C, the jaws, D, which align the drill work, as hereinafter described.
At the inner end of the said chamber, b, and at its junction with the opening C,
are formed shoulders d, d, as seen in Fig. 4, which shoulders d, d, prevent the
driver E, from falling into the opening, C, or from tilting cornerwise in the
chamber b.
ولا
which
Said driver, E, is preferably a cylinder of steel, with a diameter a little less
than the diameter of the chamber , so that when the said driver E, is in its place
in said chamber b, it can move a little from side to side therein and the relation
of the diameter of the driver E to the diameter of the chamber b, is such, that
in no position of the said driver E, can its edge get clear of said shoulders d, d.
Said driver E has a central hole, e, in its front face, to receive the end of a drill,
and said hole, e, may be square or may be a long slot, as indicated in Fig. 8; and,
of course, in place of the hole e, to receive the end of the drill, there might be a
central projection on the said driver E, and a socket to fit on such projection in
the end of the drill stock, but a hole in the driver E to receive the end of the
drill is preferable. The rear face f, of the driver, E, is a plane surface, parallel to
the front face of said driver E, and it preferably has a diametrical slot,
extends across the rear face of the driver E, and in a direction perpendicular to
the length of the slot, e. In case there is a square hole, e, in the front face of the
driver E, in place of a long slot, then the length of the said slot, will preferably
be in a direction perpendicular to the direction of the movement of the jaws D.
The said sloty, engages with an easy working fit upon a projection or a rib, h, of the
arbor H. Said rib extends diametrically entirely or almost entirely, across the end
of said arbor, H, so that the driver E, can slide to and fro along on said rib, h, and
the said arbor H, is tightly driven or screwed into the aforesaid chamber b, in the
chuck A, and enters therein just so far, that the said rib h, will be entered into the
slot in the driver E, and also so that there will be sufficient space between
the end of the arbor H, and the aforesaid shoulders. d, d, to permit of the casy
play of the driver E, in said space; and said arbor H, also serves for connecting
the chuck A with a lathe in any usual manner. Now it is evident that by reason
of the aforesaid engagement of the driver E, upon the rib, h, when the chuck A
revolves, said driver E, must also revolve, and if the end of a drill be fitted into
the slot, e, in the driver, E, then said driver E will revolve said drill. It is also
evident that in place of the aforesaid engagement of the slot, g, of the driver E
upon the rib h, there might be a rib on driver E which rib might enter a slot
in the arbor H, the latter arrangement being the equivalent of the former.
•
Now the driver, E, being adapted to engage the end of a drill stock, as herein
described, jaws, as, D, D, of any usual kind may be employed to align and hold
the drill.
In the drawings, I show such jaws, D, D, two in number, inserted in 'the aforesaid
opening, C, and, each of said jaws has a rib, d, which enters a recess, S in one of
the, walls c, for the purpose of giving a truc rectilinear motion to said jaws D, D,
and also of retaining the said jaws D, D, in the chuck, A. Said jaws D, D, each
have V-shaped teeth on their internal faces, as in Fig. '1, to grip the stock of a drill,

page_text: and on their under side, opposite to the rib d, each jaw D, has a section of a female
screw, d, d, the threads of one section being right handed, and the threads of
the other section being left handed, as shown. The said screw threads d, d, engage
upon the threads of corresponding sections of a male screw, J, which passes
transversely through an opening, L, in the chuck A, and parallel to the aforesaid
rib, d, and said screw, J, is made with two parts, j, j, united by a middle spindle /',
of smaller diameter than the parts 1, j. The aforesaid opening L, is substantially
semi-circular in section, and of a size to easily fit the screw, J, and has smooth
walls, so as not to engage with the threads of the screw, J and said opening, L,
has a collar, l, at its middle part, corresponding to the spindle j'. Thus when the
screw J is in its place in the chuck, said screw J, can turn freely but cannot move
lengthwise. Now it is evident that the jaws D, D, having been placed in-the chuck
until their threads d² d² engage with the threads of the screw, then if said screw J,
be turned in the one direction, by a key engaging upon its end, K, then said
jaws D, D, will be drawn inward until they meet in the centre of the chuck, A, and
if the said screw J, be turned in the opposite direction, then said jaws D, D, will be
opened widely apart.
The operation is as follows: A drill, N, is inserted in the chuck A, the jaws D, D,
being open, and the end of the drill N, is inserted in the slot e, in the driver E.
Then the jaws D, D, are closed on the drill N, thereby accurately aligning the said
drill. Should the drill stock be out of true, so that the end which enters the said
slot in driver E, is not accurately in the centre of the chuck, then said driver e,
will move a little to one side or the other, to compensate for the inaccuracy of the
drill end. Now the chuck being revolved in a lathe, the driver E will revolve the
drill and relieve the jaws D, D, of the strain which comes on them when said jaws
are alone relied on to revolve the drill.
Figs. 11 and 12 are views of a chuck with a pin M, which is driven quite tightly
diametrically through the chuck A, and passes with an easy working fit through
a hole, m, in the driver E. In said Figs. 11 and 12, a rib, g, is shown on the rear
face, f, of said driver E, and said rib, 9, enters a socket, h, in the end of the plug H.
The direction of said rib, g, is perpendicular to the direction of the slot, e, in the
front face of the driver, E. The general construction of the chuck A, the plug H,
jaws D, D, and screw J, (said jaws and screw not being shown in Figs. 11 and 12)
is the same as hereinbefore described, and therefore does not require further
description. It is evident that both the pin M, and the engagement of the driver E,
with the plug H, co-operate to revolve said driver E, and that either said pin M, or
said engagement between the driver E, and the plug H, may be omitted, and the
other alone relied on, to revolve said driver E.
To prevent the spreading of the walls c, c, when the jaws D are closed on a drill
stock N, I employ à face plate P, which has on its inner or rear face, strong thick
ribs p. p., in form segments of circles. These ribs p. p, are placed about midway
between the centre and the circumference of the face plate, and enter corresponding
grooves o. o. in the front face a of the chuck A. The face plate P. is secured to
the chuck A, by screws s. s, and the ribs p. p. are cut away at r, r, corresponding
in position with the chamber C, so that the jaws D. D. can move in and out through
the spaces r, r, for it is to be understood that the jaws D, D, are flush with the
front face a, of the chuck A, and move in and out under the face plate P. Said
face plate P', has a central hole y, through which drills are inserted into the chuck A,
and the hole g, limits the size of the drill which can be used in any chuck, so that
drills too large for the chuck cannot be used. It is evident that the engagement of
the ribs p. p. with the chuck A., will prevent the spreading of the chuck.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare what I claim is ;
1. The combination of a drill chuck having an axial chamber, and a driver
adapted to engage a drill inserted into said chamber so as to have a slight movement

page_text: therein, in a direction transverse to the axis of the chuck, and devices for engaging
the said driver with the chuck as described.
2. The combination of. a drill chuck having an axial chamber, a driver adapted
to engage a drill inserted into said chamber so as to have a slight movement therein
in a direction transverse to the axis of the chuck. An arbor fixed in the chuck,
and devices for engaging the said driver with the arbor as described.
3. The combination of a drill chuck having an axial chamber, a driver adapted
to engage a drill, inserted into said chamber, so as to have a slight movement therein,
in a direction transverse to the axis of the chuck, and a pin passing through the
chuck, and with easy working fit through said driver as described.
4. In combination with a drill chuck a face plate adapted to engage with the
front face of the chuck between the centre and circumference of said face as
described.
5. The combination with a chuck body having a chamber for the gripping jaws,
and a grooved face, of a face plate having a rib adapted to enter the groove in the
face of the chuck, as and for the purpose described.
6. The combination with a drill chuck having a transverse diametrical chamber
for the gripping jaws, of a face plate adapted to engage with the face of the chuck,
between the centre and circumference of the face, and having a diametrical
channel corresponding to the chamber of the gripping jaws, as and for the purpose
described.
Dated this 8th day of May 1891
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.