Adjustable quick change jaw apparatus

An adjustable quick change chuck jaw apparatus for attachment to a master jaw in the front face of a rotary chuck allows a machinist to quickly change the chuck jaws from one diameter to another. A generally rectangular jaw body is connected to the master jaw of a rotary chuck and extends radially outward from the central rotational axis of the chuck. A jaw member is slidably mounted on one side of the jaw body to travel longitudinally relative thereto and has a workpiece gripping portion extending perpendicularly outward. A rotatable shaft mounted in the jaw body has a threaded segment configured to become engaged with mating threads on the jaw member when rotated to an engaged position and to become disengaged therefrom when rotated to a disengaged position. A spring biased locking pin in the jaw body allows selective engagement with the shaft to prevent rotation thereof in a locked position and to become disengaged therefrom to allow rotation in an unlocked position. Upon depressing the locking pin, the shaft may be rotated to its disengaged position wherein the jaw member may be manually removed from the jaw body or moved thereon relative to the workpiece and accurately adjusted to grip the workpiece. Upon releasing the locking pin, the shaft is prevented from rotating and the jaw member is maintained in the adjusted position.

This application claims priority of Provisional Application Serial No. 
60/016,791, filed May 7, 1996. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to chuck jaws for lathes, mills and drill 
presses, and more particularly to an adjustable chuck jaw apparatus which 
allows a machinist to quickly change the chuck jaws from one diameter to 
another. 
2. Brief Description of the Prior Art 
Conventional rotary chucks have radially movable master jaws in a front 
face that carry removable jaws that grip the workpiece. The workpiece 
gripping jaw utilizes a base having an insert attached which directly 
grips the workpiece. The inserts are provided in different sizes and 
different gripping faces that are useable with a single base to 
accommodate various sizes and types of workpiece surfaces. It often takes 
twenty to thirty minutes to change and adjust the conventional chucking 
apparatus from one diameter to another. 
There are several patents which disclose various chuck jaw apparatus for 
reducing the time required to adapt the gripping jaw to accomodate 
different sizes of workpieces and to change the jaw insert. 
Slater, U.S. Pat. No. 4,861,048 discloses a jaw assembly which attaches to 
the master jaw of a chuck and has detachable and repositionable hexagonal 
or polygonal clamping members secured to the leading edge of the jaw. The 
clamping members can be indexed by removing a securing screw, rotating the 
clamping member to the desired position, and resecuring the screw. 
Lenz, U.S. Pat. No. 5,460,389 discloses a cylindrical jaw apparatus which 
attaches to a chuck and has detachable and repositionable cylindrical 
clamping members secured to a slide bar mounted in the chuck. The 
cylindrical clamping members have work receiving surfaces which can be 
positioned relative to the workpiece by removing the securing screws, 
rotating the clamping member to the desired position, and resecuring the 
screws. 
Roberts et al, U.S. Pat. No. 5,529,320 discloses a jaw assembly having a 
top jaw which attaches to the master jaw of a chuck. The top jaw has a 
base with a lock pin that allows jaw inserts to be quickly removed and 
replaced. 
The present invention is distinguished over the prior art in general, and 
these patents in particular by an adjustable quick change chuck jaw 
apparatus which attaches to a master jaw in the front face of a rotary 
chuck and allows a machinist to quickly change the chuck jaws from one 
diameter to another. A generally rectangular jaw body is connected to the 
master jaw of a rotary chuck and extends radially outward from the central 
rotational axis of the chuck. A jaw member is slidably mounted on one side 
of the jaw body to travel longitudinally relative thereto and has a 
workpiece gripping portion extending perpendicularly outward. A rotatable 
shaft mounted in the jaw body has a threaded segment configured to become 
engaged with mating threads on the jaw member when rotated to an engaged 
position and to become disengaged therefrom when rotated to a disengaged 
position. A spring biased locking pin in the jaw body allows selective 
engagement with the shaft to prevent rotation thereof in a locked position 
and to become disengaged therefrom to allow rotation in an unlocked 
position. Upon depressing the locking pin, the shaft may be rotated to its 
disengaged position wherein the jaw member may be manually removed from 
the jaw body or moved thereon relative to the workpiece and accurately 
adjusted to grip the workpiece. Upon releasing the locking pin, the shaft 
is prevented from rotating and the jaw member is maintained in the 
adjusted position. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an adjustable 
quick change chuck jaw apparatus which attaches to a master jaw in the 
front face of a rotary chuck and allows a machinist to quickly and easily 
change the chuck jaws from one diameter to another. 
It is another object of this invention to provide an adjustable quick 
change chuck jaw apparatus which does not require a time consuming 
procedure to position and adjust the gripping jaws relative to the 
workpiece. 
Another object of this invention is to provide an adjustable quick change 
chuck jaw apparatus which allows the gripping jaws to be quickly and 
easily positioned and adjusted relative to the workpiece by depressing a 
locking pin and sliding them manually relative to the workpiece. 
A further object of this invention is to provide an adjustable quick change 
chuck jaw apparatus which allows the gripping jaws to be quickly removed 
and replaced by depressing a locking pin and sliding them off or on a jaw 
body. 
A still further object of this invention is to provide an adjustable quick 
change chuck jaw apparatus which is simple in construction, inexpensive to 
manufacture, and rugged and rele in operation. 
Other objects of the invention will become apparent from time to time 
throughout the specification and claims as hereinafter related. 
The above noted objects and other objects of the invention are accomplished 
by an adjustable quick change chuck jaw apparatus which attaches to a 
master jaw in the front face of a rotary chuck and allows a machinist to 
quickly change the chuck jaws from one diameter to another. A generally 
rectangular jaw body is connected to the master jaw of a rotary chuck and 
extends radially outward from the central rotational axis of the chuck. A 
jaw member is slidably mounted on one side of the jaw body to travel 
longitudinally relative thereto and has a workpiece gripping portion 
extending perpendicularly outward. A rotatable shaft mounted in the jaw 
body has a threaded segment configured to become engaged with mating 
threads on the jaw member when rotated to an engaged position and to 
become disengaged therefrom when rotated to a disengaged position. A 
spring biased locking pin in the jaw body allows selective engagement with 
the shaft to prevent rotation thereof in a locked position and to become 
disengaged therefrom to allow rotation in an unlocked position. Upon 
depressing the locking pin, the shaft may be rotated to its disengaged 
position wherein the jaw member may be manually removed from the jaw body 
or moved thereon relative to the workpiece and accurately adjusted to grip 
the workpiece. Upon releasing the locking pin, the shaft is prevented from 
rotating and the jaw member is maintained in the adjusted position.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings by numerals of reference, there is shown in FIGS. 
1-8, a preferred quick change adjustable chuck jaw assembly 10 in 
accordance with the present invention. Only one jaw assembly is shown, 
however is should be understood that the present jaw assemblies are 
provided in sets of three or four. A generally rectangular jaw body 11 is 
secured to the master jaw of conventional three or four jaw rotary chuck 
(not shown) in the same manner as a conventional chuck jaw, usually with 
two hex socket head cap screws (not shown) which pass through holes 11A in 
the back wall of the body 11. The jaw body 11 extends radially outward 
from the central rotational axis of the chuck. 
The jaw body 11 has a vertical longitudinally extending T-slot 12A formed 
in one side extending the length of the body and a horizontal T-slot 12B 
formed in its top end. The opposite longitudinal side of the jaw body 11 
is provided with a pair of laterally spaced longitudinally extending 
transversely serrated or toothed surfaces 13 separated by a central 
rectangular slot 14 extending the length of the body. The slot 14 and 
parallel spaced ridges of the toothed surfaces 13 correspond to the 
toothed surface of the master jaw. 
A longitudinal bore 15 parallel and adjacent to the T-slot 12A extends 
inwardly through the jaw body 11 from one end and terminates in a reduced 
diameter bore 16 at the opposite end. A transverse bore 17 adjacent to the 
rectangular slot 14 extends through the jaw body 11 from one side and 
terminates in a reduced diameter bore 18 at the opposite side. The larger 
open end of the transverse bore 17 is provided with a threaded counterbore 
19 which receives a retainer screw 20. A small bore 21 extends between the 
transverse bore 17 and the longitudinal bore 15. An oblong pin 22 having a 
rounded end and an opposed flat end 22A is slidably received in the small 
bore 21. 
A generally L-shaped top jaw 23 having a T-shaped extension 24 extending 
the length of one side is slidably received in the T-slot 12A of the jaw 
body 11 to travel longitudinally therein. The outer surface of the 
T-shaped extension 24 has a recessed female threaded portion 25 forming an 
arcuate threaded segment which is disposed in one side of the longitudinal 
bore 15. 
An elongate actuator shaft 26 having a generally cylindrical central 
portion 27 with a reduced diameter trunnion portion 28A at its top end and 
a modified cap screw 28B threadedly engaged in its bottom end is received 
in the longitudinal bore 15 of the jaw body 11. The headed portion of the 
cap screw 28B is modified to have a smooth exterior surface to serve as 
the lower trunnion for the actuator shaft 26. The central portion 27 of 
the actuator shaft 26 has a longitudinally extending arcuate threaded 
segment with male threads 31 which extend the length of the central 
portion. Two unthreaded flat surfaces 29 extend longitudinally along 
opposed sidesof the central portion 27 and a third flat surface 30 extends 
longitudinally along the length of the central portion opposite the 
arcuate threaded portion 31 to receive the flat end 22A of the oblong pin 
22. 
It should be understood that the oblong pin 22 may have opposed rounded 
ends and that the shaft 26 may be provided with a recessed detent opposite 
the arcuate threaded portion 31 to receive the rounded end of the oblong 
pin. 
An inverted T-shaped retainer plate 32 is slidably received in the 
horizontal T-slot 12B. The retainer plate 32 has a bore 34 extending 
therethrough axial alignment with the longitudinal bore 15. As best seen 
in FIGS. 5 and 6, a dowel pin 35 extends transversely through the jaw body 
11 and the retainer plate 32 to facilitate proper aligment of the bores 34 
and 15, and the retainer plate 32 is secured in the top end of the of the 
jaw body 11 by hex socket head cap screws 33 to retain the actuator shaft 
26 in the jaw body. The T-shaped retainer plate 32 extends horizontally 
between the vertical T-slot 12A and rectangular slot 14 in the jaw body. 
The reduced diameter trunnion portion 28A of the actuator shaft 26 is 
rotatably received in the bore 34 of the retainer plate 32, and the 
modified cap screw 28B is threadedly engaged in the bottom end of the 
actuator shaft 26 through the reduced bore 16 of the jaw body 11 with its 
smooth headed portion rotatably disposed in the reduced bore 16 to serve 
as the lower trunnion. Thus, the actuator shaft 26 is rotatably mounted in 
the jaw body 11. The trunnion 28A is provided with a hex socket which 
receives a tool, such as an allen wrench, for rotating the actuator shaft 
26. When the actuator shaft is rotated, its male threaded portion 31 will 
become engaged with, and disengaged engaged from, the female threaded 
portion 25 in the T-shaped extension 24 of the top jaw 23. 
A locking pin 37 is slidably received in the transverse bore 17 of the jaw 
body 11. The locking pin 37 has a cylindrical central portion 38 and a 
reduced diameter portion 39 which which extends a distance outwardly 
through the reduced diameter bore 18 in the jaw body 11. The central 
portion 38 of the locking pin 37 has a circumferential V-groove 40 which, 
depending upon its position, receives the rounded end of the oblong pin 22 
opposite the flat end 22A which is received on the flat surface 30 of the 
actuator shaft 26. A compression spring 41 received in the transverse bore 
17 has one end engaged on the retainer screw 20 and its opposite end 
engaged on the inward end of the locking pin 37. 
As shown in FIG. 7, the compression spring 41 normally urges the locking 
pin 37 to an outwardly extended position relative to the jaw body 11. In 
this outwardly extended position, hereinafter referred to as the "locked 
position", the V-groove 40 of the locking pin 37 is out of alignment with 
the end of the oblong pin 22. In the "locked position", the flat end 22A 
of the oblong pin 22 is forced by the cylindrical surface of the locking 
pin 37 onto the flat surface 30 on the actuator shaft 26 to prevent 
rotation of the shaft. Also in the "locked position", the male threaded 
portion 31 of the actuator shaft 26 is threadedly engaged with the female 
threaded portion 25 in the T-shaped extension of the top jaw 23. 
As shown in FIG. 8, when the outer end 39 of the locking pin 37 is 
depressed inwardly against the force of the compression spring 41, the 
V-groove 40 becomes aligned with the oblong pin 22 and the actuator shaft 
26 can then be rotated freely. When the actuator shaft 26 is rotated, its 
larger radius male threaded portion 31 will become threadedly disengaged 
from the female threads 25 of the top jaw 23 and will force the rounded 
end of the oblong pin 22 into the V-groove 40 of the locking pin 37. This 
position is hereinafter referred to as the "disengaged position". 
Thus, the actuator shaft 26 can be rotated only after depressing the 
actuator locking pin 37 into a position that allows the oblong pin 22 to 
be aligned with the V-shaped groove 40 of the locking pin 37. In a 
preferred embodiment, the locking pin 37 requires a force of from about 20 
to 30 foot pounds of pressure to position its V-groove 40 to allow the 
oblong pin 22 to disengage from the actuator shaft 26. 
OPERATION 
When the locking pin 37 is depressed and the actuator shaft 26 is rotated 
180.degree. from the "locked position" to the "disengaged position" (FIG. 
8), its flat surface 30 becomes positioned adjacent to the female threaded 
portion 25 in the T-shaped extension 24 of the top jaw 23 with clearance 
therebetween. In this position, the top jaw 23 is threadedly disengaged 
from the actuator shaft 26. The top jaw 23 can then be manually moved in 
the T-slot 12A along the length of the jaw body 11 and adjustably 
positioned radially with respect to the workpiece or removed from the jaw 
body. The actuator shaft 26 may also be rotated with the locking pin 
depressed to accurately adjust the top jaw relative to the workpiece by 
the pitch of the threads 31 on the actuator shaft. 
The radial adjustment (or pitch) of the top jaw 23 is, and can be, 
variable, depending upon the particular application, the amount of the 
increment of the radial adjustment desired of the top jaw 23 and the 
amount of radial stroke of the chuck in which the jaw assemblies are 
installed. 
When the top jaw 23 is repositioned, adjusted for position relative to the 
workpiece, or replaced with another top jaw, the actuator shaft 26 and the 
shaft has been rotated 180.degree. and is then in the "locked position" 
(FIG. 7) with the male threads 31 of the actuator shaft engaged with the 
female threads 25 of the top jaw 23 and the locking pin 37 is released. 
The compression spring 41 urges the locking pin 37 outwardly and its 
cylindrical surface forces the flat surface 22A of the oblong pin 22 into 
engagement on the flat surface 30 of the actuator shaft 26. This prevents 
rotation of the shaft 26 and maintains the top jaw 23 in the adjusted 
position along the length of the jaw body 11 with respect to the workpiece 
by the threaded engagement. 
The top jaw 23 which has been illustrated as an example is designed to 
engage the inside of a workpiece. However, it should be understood that 
the top jaw 23 may also be designed to accomodate the chucking of 
workpieces on the outside, and that they may be configured to accept soft 
inserts that can be bored or turned for special applications of chucking. 
These inserts can be held in place by any conventional fastener means, 
such as a hex socket head cap screw. The top jaws 23 may also be provided 
with teeth serrations for chucking objects that have been hardened for 
resistance to wear. 
In a preferred embodiment, each top jaw 23 is engraved with a diameter set 
mark showing the actual smallest and largest diameter that the top jaw set 
will hold. The jaw body 11 is also engraved with this same diameter 
relative to the radial position of the top jaw 23, jaw body 11, and the 
centerline of the chuck that it is mounted on. The jaw body 11 is also 
engraved with the range of diameters that each set of top jaws will 
position to as seen in FIG. 1. 
Each set of top jaws will position to a range of several inches in 
diameter. Each top jaw set is engraved to show the smallest diameter 
position that the particular set will hold. The jaw body 11 is engraved to 
show the range of diameters for each set of top jaws. The diameter set 
marks are used to set the radial position of the top jaw 23 on the jaw 
body 11 in relation to the diameter of the object being chucked. The 
object can be measured in relation to diameter, then the top jaws set in a 
radial position relative to this diameter. Usually no further adjustments 
are necessary before completing the chucking. 
Thus, it can be seen from the foregoing, that the present adjustable quick 
change jaw assembly reduces the time required to change, adjust, 
disassemble and reassemble chuck jaws on a chuck, and allows top jaws to 
be quickly adjusted or changed in just several minutes. 
While this invention has been described fully and completely with special 
emphasis upon a preferred embodiment, it should be understood that within 
the scope of the appended claims the invention may be practiced otherwise 
than as specifically described herein.