IMPROVEMENTS IN LATHES, TOOL HOLDERS, AND MECHANISM OR ARRANGEMENTS FOR GRINDING TWIST DRILLS
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by William Ford Smith and Arthur
Coventry at the Office of the Commissioners of Patents on the 28th September
ISSO.
WILLIAM FORD SMITH and ARTHUR COVENTRY, of Gresley Iron Works, Salford,
in the County of Lancaster, Engineers and Tool Makers. "IMPROVEMENTS IN
LATHES, TOOL HOLDERS, AND MECHANISM OR ARRANGEMENTS FOR GRINDING TWIST
DRILLS."
Firstly. Our improvements are made upon or are applicable to what is known
as the Cooper lathe, for which Letters Patent were granted to us, numbered 1101,
dated 20th March, A.D. 1877, as a communication from William S. Cooper, of the
Firm of Cooper, Jones, and Cadbury, of Philadelphia, United States.
One of our improvements refers to means or arrangements by which the lathe
is almost instantly prepared or changed to chase screw threads of two or more
different pitches, and one of our arrangements consists in providing two or more
master screws end to end on the same shaft or axis, and as many segments of screw
nuts to suit them, these screw nut segments being secured in a shaft which can be
rotated in a bearing in the end of the arm usually employed for carrying the screw
nut segment, so that by merely turning the shaft and securing it with a pin or
other means, the desired screw nut segment is brought opposite the master screw
which is to operate when chasing, and thus by merely turning the screw nut
segment shaft, the lathe is instantly changed so as to chase a thread of a different
pitch. Another arrangement is by wheels.
The short shaft for one master screw is inade stationary, and two or more sets of
wheels are arranged to drive it, and there is a lever having studs for carrier wheels.
By moving this lever (which is held in position by notches in the bed), one or
the other of the carrier wheels is brought into gear and the other out of gear;
consequently the master screw will be driven at different speeds by one or the other
set of gearing, provided according to the diameters of the wheels brought in gear,
and thus the pitch of the screw chased will vary accordingly.
When the lever is held in mid-position both carrier wheels will be out of gear.
A clutch arrangement of gearing may be substituted for the lever and carrier
wheels if desired.
Another improvement under this head of our Invention consists in arrangements
for adapting the lathe for chasing taper screws or cone screws, and which may
also be used for parallel screws, and consists in applying an adjustable guide plate
to the frout of the bed, the lever handle from the chasing shaft or a screw in the
lever handle resting upon the edge of the guide plate, which gives the desired
inclination when chasing.

page_text: The lever handle for the chasing tool or the arm for the screw nut segment is
arranged with elasticity and a slight "play," so as to keep the screw nut segment
in gear with the master screw when the chasing tool is operating while being
lifted by the incline guide.
Another improvement under this head relates to the bearings of the oscillating
chasing shaft, and consists in making an under-cut slot the lengthway of the bed,
and in fitting the bearings so as to be adjustable in this slot, which arrangement
allows two or more of the bearings to be brought and secured closer to the lever
handle, and allows one of them to be used in place of the collar stop hitherto
employed. By this means greater steadiness can be given to the oscillating chasing
shaft, and thus vibration (which causes inaccurate and defective work) is obviated.
Another improvement consists in using an adjustable stop secured in the slot in
the lengthway of the bed, to limit the movement of the slide for the capstan
rest or forcing head.
Another improvement under this head relates to the "capstan rest," and consists
in arranging the nut of the screw for the slide in two halves, so that they can
be opened to release the screw by a handle when the rest is to be quickly drawn
back, which is done by a small toothed rack and pinion.
There is also an adjustable stop to limit the forward movement of the slide.
Another improvement under this head consists in arranging the slides of the
capstan rest so that it may be worked in a direction parallel to the lathe spindle,
and at an angle thereto, a fixed stop being used to bring the slide to the parallel
position, and an adjustable stop to fix the the required angular position of the slide,
a clamp being used to secure the slides of the capstan rest in either position.
Another improvement under this head consists in substituting an endless link
chain (which is more out of the way), in place of the toothed rack for moving the
saddle for the forcing head or capstan rest quickly to and fro along the bed.
Secondly. Our Invention relates to swivel tool holders used in lathes and other
tools, and consists in making the face of the collar and shank, which come in
contact with corresponding ratchet or other teeth, or serrations, to prevent the
cutter from twisting round and giving way under heavy cuts.
Or the collar is made with teeth on its periphery to lock with one or more teeth
on the shank of the holder.
Or a sliding or other bolt or catch is arranged in the shank to enter holes or
notches in the collar.
Or the collar is made with a cone or cones, and a corresponding cone or cones is
or are formed on or in the shank of the holder, and the cones are drawn firmly
together (which gives additional holding friction) by the bolt which secures the
cutter.
Thirdly. Our Invention relates to arrangements of mechanism for reducing the
thickness of the lips or cutting edges of twist drills used in lathes and other
tools when the central part is too thick, which is the case more especially when
the drills get worn nearer to the shank.
The central part of the lips of the drills are reduced by grinding by an emery
wheel of suitable size and shape, while held in apparatus somewhat similar to that
described in the Specification of the Patent granted to us numbered 2921, and
dated 18th July 1879, for grinding twist drills.
Our Invention consists in arranging the tool holder for the drill, which is similar
to that above referred to, on slides, by which the drill can be brought up and
against and traversed under the rotating emery wheel, and then turned half round
while the other lip of the drill is treated in like manner.