Improvements in Electrically Actuated Machine Tools.
Year: 1893

page_text: Date of Application, 24th Aug., 1893
Complete Specification Left, 24th May, 1891-Accepted, 7th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in Electrically Actuated Machine Tools.
We, HENRY WILLIAM GIBBS, of Caldwell Street, Superintendent of Agricul-
tural Implement Works, and GEORGE JAMES GIBBS, of Milbrook Road, Engineer,
both in Bedford, in the County of Bedford, do hereby declare the nature of this
invention to be as follows:-
Our invention relates to the construction of machine tools actuated by electric
currents.
According to the said invention we combine in one casting the spindle case of the
machine tool and a portion of the field magnet of the electro-motor, whereby a
convenient arrangement of mechanism is attained with less weight and cost than in
similar machines as heretofore constructed.
We also arrange the gripping magnets in a novel manner (whereby an effective
magnetic grip is obtained with relatively reduced bulk, weight, and cost), the coils
being placed within an annular recess in the feet of the gripping magnets, where
they are protected from injury, the feet being secured on the ends of columns
which also form parts of the containing frame carrying the gearing and electro-
motor.
To enable the workman to secure the tool accurately in line with the exact spot
on or in which the tool is to operate we attach to a convenient part of the frame-
work a movable index or finger made to touch the spot on which the tool is required
to work so that on turning on the electric current the gripping magnets will secure
the tool in that position without necessitating further adjustment.
The switches and resistance coils controlling the electric currents are made in
such a manner that only one lever is required for actuating the switches, the currents
exciting firstly the gripping magnets and field magnets and then actuating the
rotating armature.
By this arrangement of a single lever the resistance coils and the switches, the
gripping magnets and the field magnets of the electro-motor are when the lever is
moved in one direction first excited and the tool is thereby secured before the current
is switched into the rotating armature, thus preventing injury to the armature which
happens when with other arrangements of levers and switches the current is acci-
dentally switched into the armature before the field magnets are excited. By a
reverse movement of the lever the electric current to the armature or to the field
magnets may be separately regulated, or when stopping the tool the armature
current is first interrupted and the motor stopped before the gripping magnets are
released by the further movement of the lever.
The terminals of the wires or cables which convey the current from the switches
to the gripping magnets, field magnets and armature terminals are arranged in a
novel manner by forming the terminals male and female, and of such forms that the
male terminal on one wire can only enter and make electric contact with the female
terminal with which it corresponds for the purpose of actuating its part of the
machine tool.
Dated this with 1-
1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.

page_text: Improvements in Electrically ou
We, HENRY WILLIAM GIBBS, of Caldwell Street, Superintendent of Agricul-
tural Implement Works, and GEORGE JAMES GIBBS, of Milbrook Road, Engineer,
both in Bedford, in the County of Bedford, 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 :-
Our invention relates to the construction of machine tools actuated by electric
currents.
According to the said invention we combine in one casting the spindle case of the
machine tool and a portion of the field magnet of the electro-motor, whereby a
convenient arrangement of mechanism is attained with less weight and cost than in
similar machines as heretofore constructed.
We also arrange the gripping magnets in a novel manner (whereby an effective
magnetic grip is obtained with relatively reduced bulk, weight, and cost), the coils
being placed within an annular recess in the feet of the gripping magnets, where
they are protected from injury, and the said feet secured on the ends of columns
which also form parts of the containing frame carrying the gearing and electro-
motor.
To enable the workman to secure the tool accurately in line with the exact spot
on or in which the tool is to operate we attach to a convenient part of the framework
a movable index or finger made to touch the spot on which the tool is required to
work so that on turning on the electric current the gripping magnets will secure the
tool in that position without necessitating further adjustment.
The switches and resistance coils controlling the electric currents are arranged
in such a manner that only one lever is required for actuating the switches, the
currents exciting firstly the gripping magnets and field magnets and then actuating
the rotating armature.
By this arrangement of a single lever the resistance coils and the switches, the
gripping magnets and the field magnets of the electro-motor are, when the lever is
moved in one direction, first excited and the tool is thereby secured before the current
is switched into the rotating armature, thus preventing injury to the armature which
happens when, with other arrangements of levers and switches, the current is acci-
dentally switched into the armature before the field magnets are excited. By the
reverse movement of the lever the electric current to the armature or to the field
magnets may be separately regulated. When stopping the tool the armature current
is first interrupted and the motor stopped before the gripping magnets are released
by the further movement of the lever.
The terminals. of the wires or cables which convey the current from the switches
to the gripping magnets, field magnets and armature terminals are arranged male
and female, and of such forms that the male terminal on one wire can only enter
and make electric contact with the female terminal with which it corresponds for
the purpose of actuating its part of the machine tool.
To enable our invention to be fully understood we will describe the same by
reference to the accompanying drawings, in which :-
Figures 1 and 2 are respectively a side elevation and plan partly in section of an
electrically actuated drill; and,
Figure 3 is a section on the line 3-3, Figure 1:
Figures 4, and 6 are views of details hereinafter referred to:
Figures 7 and 8 are elevations of the opposite ends of a switch box which we
employ in conjunction with our apparatus; and,
Figure 9 is a side elevation of the same:
Figure 10 is a view of a detail:

page_text: Figures 11, 12, 13 and 14 are views illustrating a modification of our invention.
Figure 15 is a sectional view, through the switch box on the line 15-15, Figure 9.
drawn to an enlarged scale; and,
Figure 16 is a section on the line 16-16, Figure 15.
Similar letters of reference indicate corresponding parts in the several figures.
a. a' are the pole pieces of the field magnets of the electric motor and b is the
spindle case cast in one piece with the pole piece a. c, are the magnet coils and
d is the rotating armature of the electro-motor which armature is mounted on the
spindle d' having bearings in a hanger bracket d² cast on the case b and in the
standard d³ cast on the pole piece a'.
e, e are legs secured to lugs e', e¹ on the pole piece a and carrying the gripping
magnets, and e² is a steadying leg or support secured to the pole piece a¹. The
electro-magnets f, f serve the purpose of gripping or holding the apparatus to any
flat surface of iron or steel through which a hole is to be drilled, for instance the
plate f¹ Each electro-magnet has an exciting coil f² wound on a hobbin f³ and is
enclosed in a casing f* shown in end view in Figure 4 so that the magnets practically
occupy recesses at the ends of the legs. As shown the core of each magnet is
composed of a portion of the leg e to which it is applied but if desired a separate
core may be used and the leg attached thereto. In this latter case the said core
and the casing are advantageously formed in one piece.
is the drill spindle carrying the drill bit g', the feed of which is regulated by
the screw g² and hand wheel g³ in the usual manner.
The drill spindle 9 with the drill bit is caused to rotate or is driven by means of
any convenient train of gearing connecting the armature spindle d' and the drill
spindle g. As shown in Figure 1 the armature spindle d' carries a pinion which
rotates with the armature spindle and drives the wheel 1 to which is rigidly
connected a pinion ²; this pinion h² drives a wheel h³ which is rigidly connected to
a pinion (Figure 2) and this pinion h' drives the wheel mounted upon the drill
spindle g, the said wheel and drill spindle being connected by a feather or spline so
that the spindle can move longitudinally relatively with the wheel.
The wheel and pinion 2 are carried on the spindle g but rotate independently
thereof and the wheel h³ and pinion h* are carried by but rotate freely on one of the
legs or pillars e.
The pillars e, e and the drill spindle g are maintained in their proper relative
positions by means of the cross-head i fixed to the said legs the drill spindle being
free to slide and rotate therein. The cross-head i also serves the purpose of keeping
the wheels h', h² from moving along with the drill spindle as it is advanced or
withdrawn by means of the hand-wheel g³.
In order that in using the apparatus it may be adjusted so that the drilling tool g¹ is
directly over or in line with the pop of the hole to be drilled we provide an index or
centre finder which consists of an arm j, Figures 2 and 5, attached to one of the legs e
and movable thereon, the said arm having a socket j¹ fitting upon the said leg and
adapted to be held by a set screw j. In the free end of the arm; which is bent
down so as to lie against the surface to be drilled is formed a notch j³ and in the
end of the socket is formed a notch j in which a pin fixed to the lege is
adapted to engage, the said pin being so placed that when it is in engagement with
its notch, and the notch is immediately over the pop as shown in Figure 5
wherein indicates the pop, the drill bit will be exactly over the centre of the pop
also; the machine may then be secured in this position by means of the gripping
magnets. The machine being fixed the arm j is moved clear of the path of the
drill bit by turning it on the leg e for instance into the position shown by the
dotted lines in Figure 5, the set screw being then tightened to hold the arm in
this position.
We sometimes prefer to attach a pointer to the end of the arm j instead of using
the notch for indicating the centre of the hole. Such a pointer is shown at k,
Figure 6, the said pointer being represented as screwed into the arm; for the
purpose of accurate adjustment.

page_text: Three distinct currents of electricity are supplied to this apparatus, one of which
flows through the electro-magnets f,f causing the machine to be gripped to the iron
or steel object on which the drill is intended to operate, another around the
coils c, c exciting the field-magnets of the electro-motor, and a third to the armature d.
These currents are derived from one common source such as electric lighting or
power nains and are regulated and controlled by a switch and resistance coils
contained in the box shown in Figures 7, 8 and 9, 11, 12 indicating two binding
screws or terminals to which the leading-in wires or cables are connected.
13 is a block of non-conducting substance such as wood, slate or ebonite which is
fixed to any convenient part of the box 1 Figures 7 and 9 and carries a set of female
terminals m, n, o, p a similar set of female terminals m', n', o¹, p¹ being mounted in
a non-conducting block * which is affixed to some convenient part of the machine or
electro-motor as shewn in Figures 1 and 2 and which is shown detached in Figure 10
the said terminals serving to receive male terminals or plugs on the wires carrying
the three currents which have already been mentioned as being used by the
apparatus.
The connection between the terminals m, n, o, p on the box and the terminals m¹, n²,
o', pl on the block 14 on the drill is made by means of four distinct wires m², n², o², p²
respectively which are insulated from each other but for portability and safety are
bunched into one cable q which may be of any length. At each end of each of the
four wires of the cable g is a plug of such a shape and size that it can only be fitted
to its own proper terminal on the switch box and on the block 1, whereby we
ensure that no mistaken connection can be made and avoid the necessity for tracing
the connections and thereby wasting time. The plugs for the respective terminals
are indicated by the letters m³, n³, o³, p³.
Instead of arranging the plugs and terminals as hereinbefore described we some-
times arrange at each end of the cable g a block r of insulating material which
forms a holder or handle (as shewn in Figures 11 and 12 which are two views of
the said holder at right angles to each other) by means of which all the four plugs
which may be of the same shape can be inserted into their respective terminal
sockets at the same instant. Figures 13 and 14 show in plan and elevation the
block in which the said terminal sockets are formed. In practice we prefer the
plugs grouped with unequal distances between them so as to ensure that they shall
not be inserted into the terminal sockets improperly.
The connection of the terminals m', n', o¹, p' with the various coils is shown
diagrammatically by dotted lines in Figures 2 and 3 and is as follows:-The
terminal m' is connected by a wire m' to the coils of the gripping magnets f,f; The
terminal a is connected by a wire n to the coils of the field-magnets c, c and
the terminal o' is connected by a wire o to one of the brushes in electrical contact
with the commutator of the armature d, whilst the terminal p' is connected by the
wire p* with the gripping magnet coils, the field. magnet coils and the other brush
of the armature, the said wire serving as a common return wire. In other words
m³, n' and o¹ are the positive terminals of the coils in the apparatus and p¹ is the
common negative terminal or vice versa.
The construction of the switch by means of which we control the three currents
supplied to the drill will be most clearly understood by reference to Figures 15 and 16.
s is the handle of the switch by means of which a contact-bar or lever s' is actuated,
the said lever being carried on a pivot s² as shown, and t, u, v, w, a are resistance
coils arranged in series and respectively connected at one end to the contact
plates t, u, v, w, c¹ with which the lever s is designed to make contact, the coil a
being connected at the other end to the terminal n by a wire a². The contact
plate t is also connected with the terminal m by a wire t² and an additional contact
plate y is connected with the wire a² by a wire y'. It will be understood that the
pivot s being connected to the leading-in wire terminal when the lever s¹ is in
contact with the contact plate t¹ a current of electricity will flow through the
terminal m and the coils of the gripping magnets and also through the series of
resistance coils to the terminal n and the coils of the field magnets. In order that

page_text: connection shall always be established between the lever and terminal m which--
ever contact plate the said lever s¹ may be in contact with we form the contact
plate t with an extension t³ as shewn in Figures 15 and 16.
The resistance coils mentioned above are shown diagrammatically in Figure 15
and two of them are represented in position in the regulating or switch box /
Figure 9.
It is to be understood that a greater or less number of resistance coils may he
used the number of contact plates being correspondingly increased or diminished.
In order to conduct the current from the pivot s to the terminal o in the armature
circuit we mount on the pivot s² a fork shaped oscillating contact piece z adapted
to be moved by the impingement of the lever s against one or the other of two.
pins, with which the said contact piece is provided, Figures 15 and 16. One-
arm of this contact piece is adapted to rub against a contact plate ** connected
with the terminal o by a wire and thus complete the circuit through the armature.
The distance between the pins ', is such that when the lever s' is pulled over to
the position indicated by the dotted lines at 6, Figure 15, the arm 23 will be out of
contact with the plate, and that when the said lever is in contact with the contact
plates of the resistance coils (except when first moved into contact with the plate t¹)
the said arm will make contact with the plate **.
We sometimes combine a spring, or any convenient arrangement of springs and
levers, with the forked contact piece z for the purpose of preventing the arm
from falling accidentally into contact with the plate 2 or if already in contact
therewith, from falling away therefrom. In Figures 15 and 16 indicates such
a spring which is shown in contact with a projection 28 on the contact piece.
The operation of the switch is as follows:-Assume the switch lever to be in the
position indicated by the dotted lines 2 Figure 15 in which position no current can.
flow in either of the three circuits. If now the lever s¹ is moved into contact with
the plate t¹ two circuits are completed, one from the binding screw or post through
the pivot s², the lever s', the contact plate t', the wire t2, the terminal m, the wire m², the
terminal m³, the wire m', the coils of the two gripping magnets f, f, the wire pt, the
terminal pl, the wire p² and the terminal p, to the binding screw 12: the other
current flows from the binding screw ', through the pivot s², the lever s¹, the contact
plate t', the series of resistance coils t, u, v, w, a, the wire, the terminal n, the
wire n², the terminal n', the wire n', the coils of the field magnets, the wire pt, the
terminal p', the wire p2, and the terminal p, to the binding post 1².
If the lever s¹ is moved over the contact plates so as to cut out one or more of
the resistance coils the current round the field magnet coils becomes successively
stronger as each successive coil is cut out thereby causing the armature to revolve
slower and slower as is well known and thus enabling the speed of revolution of
the drill bit to be controlled. When the lever s¹ is in contact with the plate y as-
indicated by the dotted lines Figure 15 all the coils are cut out, the current then
flowing direct from the lever s through the plate y the wire y' and the wire ² to
the terminal n. As the lever s¹ is moved over the contact plates towards the plate y
it comes into contact with the pin or stud² projecting from the contact piece=
thereby causing this contact piece to be pushed forward until its arm ³ slides onto
or comes into contact with the plate and completes the third circuit the current
flowing from the binding screw through the pivot, the arm 3, the plate 2*, the
wire, the terminal o, the wire o², the terminal o¹, the armature coils, the wire pt.
the terminal p', the wire p² and the terminal p to the binding post 2.
The lever is during the whole of this time in contact with the plate
or its
prolongation ³ thereby causing the magnets, to remain gripped to the plate or
other surface to be drilled. The said levers may then be moved backward or
forwards over the contact pieces t', u', vl, w¹, 2¹, y to regulate the speed of the
armature of the motor as before described, the contact arm ³ remaining in contact
with the plate until it is required to stop the revolution of the armature and drill
bit. For this purpose the lever s' is drawn towards the position, but before it
leaves the contact plate t¹ it strikes the stud or pin of the contact piece z and.

page_text: moves the latter out of contact with the plate * thereby interrupting the current
flowing to the armature of the motor and thereby stopping the revolution of the
same; then as the lever is finally moved out of contact with the plate t¹ the
remaining two currents are interrupted and the machine is thrown out of action and
released.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In an electrically operated machine tool, the formation of the spindle case in
one piece with one of the pole pieces of the field magnet of the electro-motor,
substantially as described.
2. In an electrically actuated machine tool, the combination with the supporting
legs of the said tool of electro-magnets constructed substantially as described and
arranged in recesses at the ends of the said legs, substantially as described.
3. In an electrically actuated machine tool, a movable index-arm or finger
arranged for ensuring the tool being placed centrally over the pop or centre dot,
substantially as described.
4. In an electrically actuated machine tool in which two or more different
currents are employed, the use of contact plugs made of varying shapes or fixed at
unequal distances apart upon a holder, to prevent the circuits being improperly
connected, substantially as described.
5. In an electrically actuated machine tool in which a series of currents is
employed, the construction of a switch-box substantially as described whereby all
the currents may be controlled by the use of a single lever, substantially as set
forth.
6. The manufacture and use of the improved electrically actuated machine tool
herein before described and illustrated in the accompanying drawings.
Dated the 21th dow of Mo 1901
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.