Improvements in Lathe-chucks.
Year: 1899

page_text: Date of Application, 2nd Feb., 1899-Accepted, 1st Apr.,
1899
COMPLETE SPECIFICATION.
Improvements in Lathe-chucks.
We, JAMES CHARLES POTTER, of No. 228, Broadway, and JOHN JOHNSTON, of
No. 207, North Main Street, both in Pawtucket, in the County of Providence,
and State of Rhode Island, United States of America, Machine Tool Manufac-
turers, 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:-
The invention has reference to an improvement in a chuck adapted to be
secured to the mandrel of a lathe and used to secure the work.
The invention consists in the peculiar and novel construction of the chuck
and the mechanism for operating and adjusting the dogs whereby the same may
be adjusted independent of each other, as will be more fully set forth herein-
after.
One object of the invention is to facilitate the operation of the dogs by which
the work may be secured, or released, without stopping the lathe.
Another object of the invention is to facilitate the adjustment of the dogs and
the uncoupling of the dog-operating mechanism.
Referring to the accompanying drawings:-
Figure 1 is a side view of our improved chuck.
Figure 2 is an end view of the same.
Figure 3 is a sectional view of part of the chuck on the line A-A of Figure 1.
Figure 4 is a sectional view of part of the chuck on the line B-B of Figure 3,
showing the sliding rack-bar engaging with and operating the pinion.
Figure 5 is a sectional view of part of the chuck on the line C-C of Figure 4.
Figure 6 is a sectional view of part of the chuck showing the manner of
securing the outer ring to the main portion of the chuck.
Figures 3, 4, 5 and 6 are shown enlarged.
Similar marks of reference indicate corresponding parts in all the figures.
In the drawings a indicates the main body of the chuck consisting of a circular
disk from the rear of which extends the hub a¹ provided with the internal screw-
thread a by which the chuck is secured to the mandrel of the lathe. Into the
disk a three radially-disposed ducts or ways a³ are bored, or otherwise formed,
which extend from the periphery of the disk a to the central opening in the same.
Through the face of the disk a the slot a is cut, or formed, in which the
dogs bbb slide; the dogs consist of the bed b¹ and the rearwardly-projecting
brackets 62 and 63; the bed 1 is provided with rectangular grooves which bear
on the ways 6-1; the brackets 2 and 3 conform to the sectional shape of the
duct a³ and fit the same with a sliding fit. The dogs are provided with tapped
holes 65 65 adapted to secure the required jaws to the dogs. Each dog is pro-
vided with the screw-spindle c having a threaded-screw c¹ of large diameter engaging
with the screw-threaded nut formed in the bracket 2; a screw-thread
smaller diameter, formed near the opposite end, engages with the screw-threaded
nut formed in the bracket 63 and the pinion is secured by a spline to the
screw-spindle c between the two screw-threaded portions. The pitch of the two
of

page_text: screw-threaded portions of the screw-spindle, although differing in diameter, is
the same.
The holes d-d extend on each side of the dogs b-b from the front
to the rear of the chuck parallel with the axis of rotation of the chuck. The
rack-bar having at one end the rack 2, is placed in one of the holes d' to
engage with the pinion 3 on one side or the other of the dog as the 'chuck may
be used to hold the work by expanding or by contracting the same. The position
of the parts indicated in the drawings is when the chuck is used as a contracting
chuck.
In Figure 2 the studs are indicated, in broken lines, connected with the
rack-bars. The stud secured to the rack-bar d', extends through the slot d
and connects the rack-bar with the sliding-sleeve e on which the shipper-groove e
is formed and with which a shipper of the usual form engages to slide the sleeve e
on the hub a¹, and with the sleeve the three rack-bars d-d¹ to simultaneously
operate the three radially-sliding dogs b-b.
The ring is secured to the periphery of the disk a, which it fits closely, by
the screw f¹ as is shown in Figure 6,-three such screws fl being preferably
used to secure the ring f as is indicated in Figure 2. The ring is provided
with three screw-plugs forming the journal-bearings of the screw-spindles c
and each plug is provided with a steel washer f3 forming the thrust-bearing for
the screw c. The plugs f are secured by the screws f4 engaging partly
with the screw-plugs and partly with the ring f. The ring g is forced into
the central opening in the disk a and is provided, at three points, with the steel
disks g which form the end thrust-bearings for the screw-spindle c.
In assembling the parts the pinion 3 is held between the brackets 62 and 63
and the end of the screw-spindle c, provided with the screw of the smaller
diameter 3, is passed through the hole in the bracket 62 then through the hole
in the pinion ; then the screws c¹-c2 take into the respective screw-threads
formed in the brackets 62 and 63 until the screw-spindle has passed sufficiently
through the brackets to allow of the adjustment of the pinion in position to
be held by the spline. The screw-spindle is then revolved until the pinion is
brought in contact with the bracket 63. The three dogs having been thus
assembled are slipped into the ducts a³, formed in the main body a of the chuck,
from the periphery until they meet in the center. The finishing ring f having
been provided with the three screw-plugs f and the steel washers is then
passed over the main body a and held in position by the screws fl. The
dogs bbb carrying the screw-spindle c are then moved cutward from the center
to the periphery until the screw cabuts against the steel washers f³ and the
ends of the screw-spindles c project through the holes in the respective screw-
plugs The ring 9, provided with the steel disks gl, is then forced into place
so that the ends of the screws cabut against the disks g. The dogs are now
adjusted by turning the screw-spindle c and to secure perfect adjustment, we
provide the index h, shown in Figure 1, with a series of equidistant radial lines,
there being the same number of lines as there are teeth on the pinion, and the
end of the screw-spindle c with an index mark so that the exact position of the
pinion relative to the brackets 62 and 63 is clearly indicated. The sleeve & is
now placed on the hub a', the rack-bars are placed in their respective holes d,
and the studs are passed through the holes in the sleeve e
and screwed into the respective rack-bars d¹.
through the slots d'
Should it be desirable to adjust the chuck to larger or smaller work or for other
reasons, the sleeve e is moved back from the face of the chuck as far as the
studs can be moved in the slots d when it will be found that the racks d² are
out of mesh with their respective pinions e³ when, by turning the screw-spindle c,
any one or all of the dogs may be adjusted as desired, and by reason of the
index and mark the teeth of the pinions will be in proper position so that upon
moving the sleeve e forward or toward the face of the chuck and with it the
rack-bars d, the racks will take into their respective pinions c to properly move
the dogs b, as desired.

page_text: By the use of the peculiar adjusting screw-spindle, the pinion secured to the
screw-spindle and the rack-bar, the dogs are rigidly held in any position; they
may be moved by the sliding sleeve operated by the shipper, and the clamping
of the work and the release of the same is quickly effected by sliding the sleeve e
in one or the opposite direction.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
Claim 1. In a chuck, the combination with the dogs supported in radially-
disposed ways, of a screw-spindle having screw-thread engagement with the
dogs, a pinion on the screw-spindle, rack-bars engaging with the pinions, a sleeve
loose on the hub of the chuck, and connections between the sleeve and the rack-
bars; whereby the sliding of the sleeve on the hub operates the rack-bars and
the dogs to clamp or release the work as described.
2. In a chuck, the combination with radial ducts and ways for the dogs and
the dogs, of a screw-spindle having a pinion secured to it,said screw-spindle
being in serew-thread engagement with a part of the dog supported in the ducts
and ways, of rack-bars each engaging with the pinion of one of the screw-spindles,
and means, substantially as described, for operating the rack-bars simultaneously;
whereby the dogs are firmly held and the work secured, as described.
3. In a chuck, the combination with radial ducts and ways for the dogs and
the dogs, of screw-spindles each having a pinion secured to the spindle, said
Screw-spindles being in screw-thread engagement with the dogs, of rack-bars each
engaging with the pinion on one of the screw-spindles, means, substantially as
described, for operating the rack-bars and graduated indexes surrounding the end
of the screw-spindle; whereby the several screw-spindles may be turned through
a predetermined part of a revolution, or revolutions, and the dogs accurately
adjusted, as described.
4. In a lathe-chuck, the combination with the disk a, the hub a', the ducts a³
extending tangentially through the disk a, and the slots at, of the dogs b, the
brackets 62 and 63 on the dogs fitting the ducts a³ with a sliding fit, the screw-
spindles c, the screw-threads c¹ and c² of different diameter and the same pitch,
the pinion c³ connected with the screw-spindle, the rack-bars d', the stud d³, and
the sleeve e having the groove el adapted to be operated by a shipper; whereby
the dogs may be operated to hold and release the work, as described.
Dated this 22nd day of October D 1808
JAMES CHARLES POTTER.
JOHN JOHNSTON.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.