Improvements in and relating to Tools or Cutters for Turning Irregular Forms.
Year: 1891

page_text: Date of Application, 4th Aug., 1891-Accepted, 26th Sept., 1891
COMPLETE SPECIFICATION.
Improvements in and relating to Tools or Cutters for Turning
Irregular Forms.
I, THOMAS WILLIAM GARDINER, of Worcester, in the County of Worcester
and State of Massachusetts, United States of America, Lastmaker, 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 a knife for turning irregular forms and especially to
what is known as the finishing knife as commonly used in lathes for turning
irregular forms and it consists in its essential features in an annular knife journalled
in a knife holder, which is attached to and carried by the rotating cutter-head of
the lathe.
In the following description of the nature of my invention and the mode of
carrying the same into effect reference is made to the accompanying drawings and
to the reference letters marked thereon, like letters indicating like parts in the
several views.
Figure 1, is a top view of a lathe for turning irregular forms showing such
portions of the operating mechanism as are necessary to illustrate the nature and
advantages of my invention.
Figure 2, is a side view of the revolving cutter-head shown upon a larger scale.
Figure 3, is a top view of the cutter-head and showing the position of the block
to be turned with reference thereto.
Figure 4, is a side view, in full size, of my improved knife and its supporting
knife holder.
Figure 5, is a top view of the same.
Figure 6, is a sectional view on line X, X, Figure 5, and
Figure 7, is a detached view of the annular rotating knife.
In turning irregular forms by means of the well known form of turning lathe for
that purpose, a model of the shape to be produced is hung upon a slowly revolving
arbor whose axis is coincident with the axis of the block to be turned and which
has a corresponding rotating motion. In Figure 1, the model is represented at A,
the block to be turned at B, both model and block being carried in a frame capable
of a swinging motion to which force is applied by means of a weight, or spring to
press the model A, against a wheel C, turning upon a fixed stud and having a
rim C', provided with a circular face which rests against the model A.
As the model A, is rotated against the model-wheel C, a swinging motion will
be imparted to the frame carrying the model A, and block B, caused by the
irregularity of the model and carrying the block B, toward, or away from the
revolving cutter-head D. The cutter-head D, consists of a cylindrical block
carried upon an arbor and rotated by the pulley D'. To the cutter-head D, are
attached a series of cutting knives 1, 2, 3, 4, 5 and 6. Each knife is placed in a
different plane of rotation so each knife will take a chip from the block B, at each
rotation of the cutter-head D, as the revolving cutter-head is longitudinally fed to
the work.
The last knife, or knife 6, is usually curved into a circular form, forming an are
corresponding with the curved rim C, of the model-wheel C, and the cutting edge
is placed at the same radial distance from the axis of the cutter-head D, as the
radius of the curved rim C', of the model-wheel in order to insure an exact
uniformity between the model A, and the turned block B, as left by the finishing
knife 6. In practice it has been found difficult to preserve the precise curvature

page_text: required in the finishing knife during the repeated sharpening of the knife and it is
to obviate this difficulty which forms. the chief object of my present invention.
In Figure 1, I have shown at 6, the ordinary form of curved and rigid finishing
knife commonly used in lathes for turning irregular forms, the remaining figures
showing a finishing knife embodying my invention.
Instead of the ordinary form of finishing knife as represented at 6, Figure 1, I
attach a knifé holder E, to the cutter-head by means of a bolt E', passing through
an elongated hole E, in the stem E³, of the holder so as to allow a radial
adjustment of the knife holder upon the cutter-head. The knife holder E, consists
of a ring formed integrally with the stem E³, and within which is journalled an
annular rotating knife F, with its cutting edge F, projecting below the holder E.
The knife F, has an internal bevel F2, which is ground by a conical, or tapering
emery wheel when the knife is sharpened, thereby preserving a uniform diameter
of the cutting edge F¹, corresponding with the diameter of the rim C¹, of the
model-wheel C, and the journal F³, of the knife is provided with an annular
groove F, to receive the end of a screw G, held in the knife holder E, by which
the knife is retained within the holder E; the thrust upon the knife in the operation
of cutting being received by the shoulder F, resting against the lower edge of the
knife holder E.
As the cutting action of the knife, as it is brought into contact with the block to
be turned, is at one side of the plane of rotation of the center of the annular knife,
the knife will be made to rotate in its bearing by the resistance of the work against
its edge bringing the entire cutting surface of the knife into action and rendering
the wear more uniform around its entire extent.
When dull, the knife F, is easily removed from the knife holder E, by with-
drawing the retaining screw G, and the cutting edge F¹, sharpened by a circular
grinding wheel working against the inner bevel F, grinding it equally upon all
sides and thereby preserving the diameter and true circular shape of the knife..
When the knife is worn out, a new one can be inserted in the holder E, without
removing the holder from the cutter-head, thereby preserving the radial position
of the knife.
The constant adjustment of the knife in order to correct the variations caused by
its unequal wear is therefore entirely avoided and the duration of the knife is
extended as the cutting edge is greatly increased.
While I deem it preferable to allow the annular knife F, to rotate freely within
the knife holder E, and be turned more or less by the action of the block B, against
its cutting edge when in operation, I do not confine myself to the free rotation of
the knife, as it is obvious that the knife could be held within the knife holder by
means which would prevent its free rotation when in operation, but which would
allow the knife to be turned within its knife holder as successive portions of its
cutting edge F³, became dull.
I do not confine myself to the specific construction shown and described, whereby
the annular knife is held in its holder as other means can be obviously employed
for the purpose.
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 that what I
claim is :
1. The finishing knife for turning irregular forms, said knife comprising a ring,
or holder attached to a revolving head and an annular knife capable of being turned
in said ring, or holder, so as to bring different sections of its cutting edge into
action.
2. The finishing knife for turning irregular forms, said knife consisting of an
annular ring having a continuous cutting edge forming a complete circle and carried
by a revolving cutter-head.
3. In a machine for turning irregular forms, the combination with the revolving
cutter-head, of an annular knife holder carried by said cutter-head and an annular

page_text: knife journalled in said holder so as to be rotated by the contact of the knife with
the work.
4. The combination with the revolving cutter-head, of an annular knife holder
attached to said cutter-head, an annular knife journalled in said holder and
provided with a groove F, and a retaining screw G, held in said holder, said
annular knife being provided with a shoulder F, bearing against the edge of the
knife holder.
5. The combination with the revolving cutter-head, of the annular knife
holder E, provided with a stem E³, by which it is attached to the cutter-head and
an annular knife F, journalled in said knife holder as shown and described.
Dated this 20th day of July 1891.
THOMAS WILLIAM GARDINER.