IMPROVEMENTS IN DRILLING MACHINES
Year: 1884

page_text: I ALEXANDER MELVILLE CLARK of the firm of A. M. and Wm Clark of
53 Chancery Lane in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of the said invention for "IMPROVEMENTS
IN DRILLING MACHINES" to be as follows:-
This invention relates to an improved drilling machine wherein the tool is
thrown into gear just at the moment when it encounters the resistance of the
work to be drilled and thrown out of gear as soon as the work is drilled when the
resistance ceases.
This two fold result which is obtained in an absolutely automatic manner
without however modifying the mode of using existing machines except by
simplyfying it, presents the following principal advantages.
1. The workman can hold the article to be drilled by one hand in such a manner
as to direct it at will.
2. The general arrangement of the machine is such that the workman cannot be
caught and injured by the driving gear.
3. The drilling machine has only a single spindle and is consequently simplified
in construction and working and requires less driving power.
In order that the invention may be inore readily understood it is represented in
the annexed drawing by way of example.
Figure 1 represents a side elevation of a drilling machine mounted on a pillar
and driven by a belt.
Figure 2 is the corresponding front view.
Figure 3 shows the machine as worked by hand. In these figures the same
letters refer to the same parts. The shaft which carries the tool, turns in
bearings carried by the frame b. This shaft is screw threaded at the upper end
and works in a tapped socket c. Upon the screw socket c is keyed a toothed
wlicel the working of which will be described afterwards.
The shaft a is driven by the bevel wheel e fixed on the driving shaft and gearing
with a second one f on the shaft a which slides through said wheel in order to raise
and lower the tool the wheel and shaft being connected by a key sliding in
keyway o in the shaft.
2

page_text: In figure 3 the toothed wheel d gears with a pinion g on the intermediate
shaft which pinion gears with a third wheel i fixed on the shaft k which rests on
a footstep and carries a fly whcel m at its upper end. In figures 1 and 2 this
wheel bas arms formed like screw vanes, so as to offer greater resistance to the air
and the pinion g is omitted the wheel i gearing directly with the wheel d.
When the machine is set in motion the shaft a is caused to screw itself down by
turning without moving the gear d, g and i. As soon as the tool meets the work
the resistance of the latter tightens the screw in the socket c whereupon the
wheels dg and i commence to turn and the fly wheel m turns with a speed which
can he regulated according to the work by means of the friction clip x as shown
in detail in figure 4 which is split and caused to clip more or less the fly wheel
shaft m by turning the tightening screw y. The tool penetrates the work with a
force proportional to the velocity of the fly wheel.
When the work is drilled the crank handle is stopped by holding it, or the
driving belt is disengaged whereupon the speed acquired by the fly wheel m
transmits motion from wheel i to wheel d whereby the shaft a is caused to screw
itself up thus raising the tool automatically.
A fly wheel p is fixed directly on the shaft a and the fly wheel m can be replaced
by two arms terminating in vanes adjustable radially by means of the screws.
The shaft a instead of sliding through the wheel ƒ can have a pinion keyed on it
of sufficient length to rise and fall with the shaft and driven by a crown wheel.
In driving by a belt a friction or other clutch worked by the fork 8 is interposed
between the pulley and its shaft. The framework can be mounted either on a
carriage or slide so that the machine can be moved about at will.

page_text: I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of 53,
Chancery Lane, in the County of Middlesex, Fellow of the Instituto of Patent
Agents, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN DRILLING MACHINES," and in what manner the same is to be performed, to bo
particularly described and ascertained in and by the following statement :-
This Invention relates to an improved drilling machine in which the tool is self-
feeding or engaging and self-releasing or disengaging immediately it has passed
through the work.
The machine which is of very simple construction, presents the two following
essential and practical advantages:
1st In hand drills the workman can hold the work by one hand, while he
operates the drill with the other and as the tool is self releasing and raising there
is a saving of the time usually required for this operation, thus enabling the
machine to work much more rapidly than others of the same kind.
2nd The machine is so arranged that the motion is reversed in the event of any
object becoming caught in the gear, so that there is no danger of the workman's
hand being crushed between the wheels as is frequently the case with the machines
now used. The machine can be varied in construction according to the nature of
the work or mode of driving it, but it is in all cases based on the principle of
causing a screw threaded part of the drill spindle to work on a nut in combination
with one or more fly wheels, for imparting the feeding and releasing motions to
the tool.
In order that the Invention may be more readily understood I have illustrated
two arrangements of the machine in the accompanying drawings. Figures 1 and 2
show respectively a front and side elevation (the latter partly in vertical section) of
a simple form of drill driven by hand. Figures 3 and 4 show similar views of a
power drill.
In these figures the same letters refer to the same parts.
a is the drill spindle screw threaded at its upper end which works in a nut b
upon which is keyed a toothed wheel c for operating a fly wheel & through the
pinion e. A spring band brake may be mounted on the bearing of the fly wheel
spindle d or tho fly wheel may be provided with vanes or other means of retarding
its motion, but it is preferred to employ the brake shewn in figures 1 and 2
consisting of a spring; having brake shoes at the ends which press against the
spindle and which is fixed and adjusted by a screw stud o. The drill spindle is
driven through a pair of bevel wheels f g is a screw adjustment thrust bearing
which may be continuously lubricated either automatically or otherwise.
Figures 3 and 4 represent a machine intended for drilling holes of large diameter
capable of working at two speeds and provided with a fly wheel h at one side which
is of dimensions suited to the kind of work and takes the place of the small fly
wheel i fixed upon the drill spindle, in the preceding arrangement. The difference
in speed is obtained by the change wheels K represented in dotted lines in figure 4.
is a clutch of any suitable kind upon the driving shaft.
It will be evident that the form of the framing, as well as the arrangement of
the accessory parts of the machine, such as the carriage or slide &c, may be varied
to suit the different kinds of work to be performed, without departing from tho
Invention.
The screwed drill spindle works casily in the nut b so that when the machine is
set in motion the drill will descend at each revolution of its spindle a distance

page_text: equal to the pitch of the screw without turning the nut b until the tool meets the
work when the friction due to the thrust of the screw in the nut causes the latter
to turn and sets the fly wheel d in notion. The rotation of nut b thus tends to
retard the feed of the drill and proportionally increases its penetrating power, this
retardation being proportional to the thrust of the screw upon the nut, or in other
words to the resistance of the work duc either to the hardness of the material or
the diameter of the hole to be drilled.
The fly wheel & whose speed is higher than that of the tool spindle a, serves on
the one hand to check the rotation of the nut b by the spindle a and consequently
to ensure the feed of the tool proportionately to the resistance and on the other
hand to store up the necessary power to raise the tool at the precise moment when
on passing through the work it no longer meets with any resistance.
Having thus described and ascertained the nature of the said Invention, and
in what manner the same is to be performed, I declare that what I claim is :-
--
1 In a drilling machine, the combination with the screw threaded drill
spindle a of a nut b which is capable of rotary but not of longitudinal motion, and
a fly wheel & receiving rotary motion there-from, whereby the tool is made self-
feeding or engaging and self-releasing or raising as herein specified.
2nd In a hand drilling machine in which the tool is self-feeding and engaging
and self-releasing or raising as herein described the combination of the screw
threaded drill spindle a, nut b, regulation screw g, and fly wheels d and i, the
former provided with a spring brake j together with their operating gear as
described with reference to figures 1 and 2.
3rd In a drilling machine driven by power in which the tool is self-feeding and
engaging and self-releasing and raising the combination of the screw threaded drill
spindle a, nut b, regulating screw g, and fly wheels d and has described with
reference to figures 3 and 4.
Dated this 1st day of Antalia 1001