Improvements in Boring and Internal or Female Screw-cutting Tools, and in Rests therefor.
Year: 1898

page_text: Date of Application, 26th Nov., 1898-Accepted, 7th Jan., 1899
COMPLETE SPECIFICATION.
Improvements in Boring and Internal or Female Screw-cutting Tools,
and in Rests therefor.
I, JAMES THOMAS DUNSTAN, of 64, Cardiff Road, Aberdare, Glamorgan, Engine
Fitter, 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:-
This invention has reference to the operations of boring and internal screw-
cutting in iron, steel and other metals.
When the diameter to be bored or cut is not sufficiently large admit of the
use of other ordinary tools, it has heretofore been the practice to use tools which
have a square or rectangular shank or heel-piece made in one piece with the stem
and which shank or heel-piece constitutes the tool "rest." Upon this "rest"
bear the glands by which the tool is clamped in position on a lathe or other
machine adapted for boring. Under the system heretofore prevailing either a
separate tool is required for each piece of work of different length, or the
stem of a tool must be altered to correspond approximately in length with the
face to be cut.
Now, according to my invention, a tool for boring holes or passages of small
diameter such as hereinabove indicated or for screw-cutting therein, has a stem
which is cylindrical and of uniform diameter throughout. The rest is separate
therefrom. Consequently, the same boring or screw-cutting tool is available for
use in operations of varying length, as the tool can be moved backwards or for-
wards in the rest to meet the requirements of cases.
Referring to the accompanying sheet of drawings, Fig. 1 represents a boring
tool a adapted, in accordance with this invention, for use in boring holes, cylin-
drical passages and channels under a given diameter, that is to say, holes,
passages, and channels of a diameter not sufficiently large to admit of boring
with the tools which are ordinarily used for larger diameters, as is well under-
stood. The diameters for dealing with which my invention is applicable may be
stated, approximately, at from four inches down to, approximately, half-an-inch.
The tool differs from those hitherto used for the same purpose in that it has
no rectangular or square part made in one piece with it at the heel. At Fig. 2
is shown in side view, and at Fig. 3 in end view, a rest b devised in accordance
with this invention to take the tool. In this rest the groove or bed c for the tool
is a semi-circular concavity or part of a circle of a diameter corresponding
approximately with that of the tool which it is to take.
Fig. 4 is a side view of the tool a and rest b; the tool lying in the rest. Fig. 5
is an end view showing the tool a in the rest b and clamped by the rest gland d
which is of the kind ordinarily employed and is applied in the usual way.
At Fig. 6 is shown in end view a rest b in which the channel or groove to
receive the tool is V-shaped.
The channel or groove may be variously shaped and it may be ribbed or

page_text: roughened so as to assist in preventing slipping of the tool in the rest. When
the groove is a part of a circle, such circle preferably corresponds in diameter
with the boring tool stem.
The tool a being, as aforesaid, made without a square or rectangular shank, is
capable of being moved backwards and forwards in the rest, and hence the same
tool can be used in borings of varying length.
The above description of my invention in its application to boring tools
applies equally to internal screw-cutting tools.
Having now particularly described and ascertained the nature of this invention,
and in what manner the same is to be performed, I declare that what I claim is:-
Tools and rests for use in boring and screw-cutting at diameters of from, approxi-
mately, four inches downwards to, approximately, half-an-inch; the said tools being
characterized by the absence of a square or rectangular shank or heel-piece, and
the said rests therefor being separately made and grooved or channelled to receive
the tools, substantially as herinabove described with reference to the accompany-
ing sheet of drawings.
Dated ORAL 1
1000
NICHOLAS WATTS,
Chartered Patent Agent, Bristol.