An Improved Drill or Tool for Drilling and Shaping Holes.
Year: 1890

page_text: Date of Application, 26th July, 1890
Complete Specification Left, 27th Apr., 1891-Accepted, 30th May, 1891
PROVISIONAL SPECIFICATION.
An Improved Drill or Tool for Drilling and Shaping Holes.
I HENRY GRAFTON of Wardrobe Chambers, Queen Victoria Street, in the City
of London, Engineer do hereby declare the nature of this invention to be as
follows:-
My invention cousists of what may be termed an expanding drill comprising bits
or cutters pivoted or otherwise mounted in a stock or spindle so that their cutting
edges shall be movable in the radial direction and combined with a cam whereby
the bits or cutters are during each revolution caused to project to a variable extent
so as to cut holes of square or other form, which as well as the size of the hole is
determined by the shape of the cam, the drill stock or spindle (which may have a
drill point) being centered in the work and revolving about a fixed axis.
Dated July 26th 1890.
H. GRAFTON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
An Improved Drill or Tool for Drilling and Shaping Holes.
I, HENRY GRAFTON of Wardrobe Chambers, Queen Victoria Street, in the
City of London, Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer
tained in and by the following statement:-
My invention relates to a drill for cutting or drilling holes of other than circular
form but generally of square or other angular form. This improved drilling tool
consists essentially of a pair of bits or cutters so pivoted in a spindle that their
cutting edges shall be movable radially and combined with a cam whereby the
bits or cutters are caused to project to a variable extent as many times during
each revolution as there are angles to the holes to be cut, the drill spindle
being centred in the work. The construction of this tool is such that it may
readily be used in an existing drilling machine without modification, and its
operation is such that no side or transverse stress is put upon the spindle as in
existing square drilling machines. Its function is to bring a round hole to the
square or other form desired, by a drilling or end cutting and not by a side
scraping action, and, as the bulk of the metal is drilled out by an ordinary
twist drill, leaving only a relatively small amount to be removed to bring the
hole to the desired angular shape, the operation may be rapidly performed.
Morcover, as the tool has two cutters and is firmly centred in the work a
much heavier cut may be taken than with the existing square drill.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figures 1 and 2 are elevations, at right angles to one another, of the improved
drill, the cutters being fully expanded.
Figure 3 is a similar elevation, the cutters being contracted.
Figure 4 is a top plan of the cam plate.
Figure 5 is an underside plan of the cam plate, showing the cams.
Figures 6, 7, 8, and 9, shew details.
The same letters of reference denote like parts in all the figures.

page_text: A is the drill spindle or stock adapted to be secured in the spindle of an
ordinary drilling machine. It is fitted to rotate at the upper part in a stationary
cam plate B. C are the two levers forming the bits or cutters pivoted scissors-
wise on a cross-pin c in a part of the spindle which is of square section (see
Figure 8) the lower members of the cutters crossing, and working past each other in
a diametrical slot a in the lower part of the spindle which is of circular section.
The
upper members or tail ends of the said levers terminate in pins having spherical
anti-friction rollers thereon, which as the drill revolves roll against the inner faces
of four cam bars D fixed to the underside of the plate 13 said cam bars being
arranged in the form of a figure corresponding in shape to the hole to be drilled in
the work, the form being square in the example illustrated. These tail ends work
in slots in the ends of a cross-head F (see Figure 6) fixed on the square part of
the spindle, whereby the cutters are carried round therewith and torsional strain is
resisted. The cutters are kept projected to the utmost extent which the cam bars
will allow of, by springs G applied to their tail ends. The cam plate B is held
between collars on the spindle and is prevented from turning by a lever H (see
Figure 9) fixed to its upper side by bolts passing through slots in the head of the
lever and screwing into any two of a circle of holes in the cam plate, according
to the desired angular position of the hole to be drilled. One of the cutters is
shewn separately in Figure 7 looking towards the back or side opposite to the
cutting face. The cutting edge extends from 1 to 2 and is curved longitudinally to
an arc described from the pivotal centre of the cutter. The cam bars are fixed to
the plate by bolts passing through transverse slots in the bars so as to admit of a
certain amount of adjustment of the bars, and the bars are exchangeable for others
to allow of the figure which they circumscribe being varied in form and dimensions
in order to correspondingly vary the hole drilled.
The tool is used by first drilling a circular hole in the ordinary way, preferably
of a diameter equal to the side of the square hole to be formed, and into which the
lower end of the spindle would fit, the action of the bits being to convert the
circular hole into one depending on the configuration of the cam, by an end cutting
or drilling action.
In order that the form of the hole produced shall correspond to the configuration
of the cam it is essential that the extreme outer end of the cutting edge of the bit,
the pivotal axis, and the axis of the antifriction ball at the upper end of the lever
should be in the same straight line, but the invention is not limited to this
arrangement which is only adopted for the sake of simplifying the shape of
the cam.
It will be obvious, without description, that the relative actions of the spring
and cam upon the cutter levers may be reversed without departing from this
invention.
It will also be obvious that a single pivoted cutter, instead of a pair of cutters,
might be used but with less advantage.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is
:
1. A drilling tool for cutting holes of other than circular form, consisting of a
cutter or pair of cutters pivoted to a spindle in combination with springs and a
stationary cam whereby the acting ends of the bits or cutters are caused to project
to varying extents during each revolution, substantially as specified.
2. The herein described drilling tool, consisting of a cutter or pair of cutters
pivoted in a slotted spindle, in combination with springs and stationary cam acting
on the cutters, as described, the lower end of the spindle being of circular section
and adapted to centre the tool in a circular hole drilled in the work for that purpose
and for removing the bulk of the metal to be drilled out, as specified.
3. In the herein described drilling tool, the combination, with the cutters pivoted
to a spindle, as described, of a can for acting thereon, as described, constructed of

page_text: bars which are adjustable in the radial direction, substantially as, and for the purpose,
specified.
4. In the herein described drilling tool, the combination, with the pivoted
cutters and stationary cam, arranged for operation as described, of spherical
antifriction rollers applied to the cutter-levers, as, and for the purpose, specified.
Dated this 27th day of April 1891.
H. GRAFTON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.