Improvements in Pencil Sharpening Machines.
Year: 1896

page_text: Date of Application, 17th Mar., 1856-Accepted, 2nd May, 1896
COMPLETE SPECIFICATION.
Improvements in Pencil Sharpening Machines.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23 Southampton Buildings in the
County of London, Patent Agent, do hereby declare the nature of this inven-
tion, (a communication to me from the A. B. Dick Company, a corporation
organized and existing under the laws of the State of Illinois, in the United
States of America, and having its principal place of business at Chicago in said
State, Manufacturers) and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
This invention relates to that class of pencil sharpening machines in which
rotary cutters or grinders are employed, and which are also caused to revolve
around the pencil, the movement of the cutters being what is commonly called a
planetary motion. The machines heretofore constructed on this principle were
objectionable for several reasons, the principal reasons being the frequent breakage
of the lead, the necessity for frequently replacing the cutters or grinders, since
they become dull very quickly, and the difficulty in properly feeding the pencil
forward or in adjusting the cutter or grinder to the pencil as the end of the pencil
is reduced in producing the point.
These objectionable features are avoided by employing two like cutters or
grinders working on opposite sides of the pencil and between which the pencil
is firmly held by pushing it forward by hand. To facilitate the sharpening of the
pencil, a guide or support is provided, which, in conjunction with the cutters or
grinders working on opposite sides of the pencil, prevents all lateral movement of
the pencil, and thus the breaking of the point is avoided.
When cutters are employed they are preferably provided with a large number
of cutting edges, and since the two cutters operate at the same time, the sharpening
of a pencil is accomplished with about half the number of revolutions of the
cutter than were heretofore necessary. Thus each individual cutting edge has less
work to perform, and hence the cutters will remain sharp a very much longer time
than the cutters heretofore employed.
The two cutters are so arranged that the axial centre of one is slightly in
advance of the other, and the diameter of the gear-wheel carried by one is some-
what less than the diameter of the gear-wheel carried by the other, so that the
cutters revolve at different speeds, and so that the relative positions of the cutting
edges are constantly changing, whereby a smooth and evenly cut surface is
produced; and a further object of rotating two cutters at different speeds is to
prevent the pinching of the pencil, which would sometimes happen if the
cutting edges of the cutters were exactly opposite each other when engaging
the pencil.
The invention is illustrated in the accompanying drawings, in which
Figure 1, is a partial side elevation and longitudinal section;
Figure 2, a plan view with the operating handle omitted, and a pointed pencil in
position to show the relative positions of the pencil and cutters;
Figure 3, a cross section on the line X-X of Figure 1, looking in the direction
of arrow 3;
Figure 4, a cross section on the line X-X of Figure 1, looking in the direction
of arrow 4; and
Figure 5, an end elevation showing two positions of the supporting base or
bracket

page_text: Referring to the drawings, A is a base or bracket having two arms a. Pivoted
between the arms a by means of screws a¹ is a case B.
The case B contains a drawer or slide 6 for receiving the dust formed by the
cutting of the pencil, and this drawer slides between two ledges b', one of which is
on each side of the case B. At the upper right-hand end of the case B is formed
a bearing C for a spindle d which at its inner end carries a yoke D, upon which
the cutters are mounted. The outer end of the spindle d is provided with a
crank D' for rotating the same. On the same side of the case B is rigidly secured
a stationary gear E, which is concentric with the spindle d. The yoke D carries
two revolving cutters or grinders F and G, the cutter F having a spindle mounted
in a bearing in one arm of the yoke D, and at the other end, the spindle is provided
with a bevelled gear f¹ meshing with the stationary gear E. The cutter G has a
spindle g mounted in a bearing in the other arm of the yoke D, and at the outer
end is provided with a bevelled gear g' also meshing with the stationary gear E.
The gear g' is somewhat smaller in diameter than the gear-wheel f¹ in order that
the cutters F and G will revolve at different speeds. The arrangement of gear-
wheels and g and stationary gear E, produces a planetary motion of the cutters
when the spindle d is rotated, as will be readily understood.
The two cutters overlap slightly, as shown in Fig. 2, and the cutting edges are
so formed that the pencil will be cut from the point backward. This is an
important advantage. Where the cutters act in the opposite direction, that is,
from the body of the pencil toward the point, the cutting edges are liable to grasp
the lead, breaking it off and pulling it from the wood. It has also been proposed to
sharpen the pencil by cutting it circumferentially as distinguished from a lengthwise
cut. This also is an objectionable method, since both the wood and lead are liable to
be split and broken. This cannot happen when the cutters act from the point of the
pencil backward. The cutting edges of the cutters are of short length, since only a
very small surface of the pencil is acted on by the cutters as they revolve around the
pencil. The axial centre of the cutter F is slightly in advance of the axial centre
of the cutter G, as before stated, in order to bring them sufficiently close together
to produce a sharp point on the pencil. If this were not done, the cutters would
have to be sufficiently far apart to prevent their cutting edges striking, and hence
a sharp point could not be produced, but, on the contrary the point of the pencil as
the pencil is fed forward, would pass beyond the periphery of the cutters, which
would result in the production of a long cylindrical like point to the pencil, which
in most cases would break off. From an examination of Figure 2, it will be seen
that as the pencil is fed forward, the point passes beyond the periphery of the
cutter F, but it will still be in contact with the cutting edges of the cutter G,
thus producing a conical point and preventing the point being broken off by reason
of its having no support; and it will also be seen that the pencil point could in no
way extend beyond the cutter G, since that cutter constantly reduces the surface
and maintains a conical point.
Mounted within the case B opposite the cutters is a guide for the pencil. This
guide comprises two pivoted L shaped levers having laterally projecting arms h
and and downwardly projecting arms and i respectively. These two levers
are pivoted to the case B by bolts k. The arms and are provided with
V-shaped recesses for grasping the pencil, which is inserted through the hole¹
in the case B. The two arms and i¹ are connected by a link m, to one end of
which is connected a spiral spring m', the other end of the spring being secured to
the case B at m². The object of the liuk m is to move the arms haud i uniformly,
and the spring m' is provided for the purpose of causing the arms to grasp the
pencil and at the same time to hold the arms in a central position relative to the
cutters, or, in other words, in such position that the axial centre of the pencil will
pass through the axial centre of the spindle d, so that when the pencil is operated
upon by the cutters, the end of the pencil is reduced to a perfect cone. The
arms h and i are separated to release the pencil by depressing the finger piece n
and to facilitate this action a rigid finger piece n' is provided on the casing B, so

page_text: that by grasping the two and pressing finger piece n, arm h will be tilted upward,
at the same time tilting arm h¹ to the right, which, through link m, tilts arm i¹ in
the same direction, causing the arm i to be moved downward. From this it will be
seen that the arms and i always move toward and away from each other uniformly.
In opening the arms to release the pencil, spring m¹ is placed under increased
tension, and upon the finger piece n being released, the spring will pull the arms
backward toward their normal positions. The armi is preferably a double or
bifurcated one, as shown in Figure 2, so that the arm h will extend between
the two parts of the armi thus forming a longer and more rigid bearing for the
pencil and guarding against any wabbling thereof.
The case B is held rigidly between the two arms a by screws a² which enter
holes as in the sides of the case. The base or bracket A is shown in position for
securing the apparatus upon a table, but if it is desired to secure the apparatus to
a wall or other vertical support, the screws a² are removed and the bracket is
swung around to the position shown in dotted lines in Figure 5, and the
bracket is locked in this position by inserting the screws a² in holes a* (see
Figures 4 and 5).
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. In a pencil sharpening machine, the combination with two rotary cutters or
grinders adapted to work on opposite sides of a pencil, of means for giving a
planetary motion to said cutters, and a guide for holding a pencil, substantially as
set forth.
2. In a pencil sharpening machine, the combination with two rotary cutters or
grinders adapted to work on opposite sides of a pencil, the axial centre of one
being in advance of the axial centre of the other, of means for giving a planetary
motion to said cutters or grinders, and a guide for holding a pencil, substantially
as set forth.
3. In a pencil sharpening machine, the combination, with two overlapping rotary
cutters or grinders adapted to work on opposite sides of a pencil and the axial
centre of one being in advance of the axial centre of the other, of means for
giving a planetary motion to said cutters, and a guide for holding a pencil,
substantially as set forth.
4. In a pencil sharpening machine, the combination with two rotary cutters or
grinders adapted to work on opposite sides of a pencil, of a yoke having bearings
for the spindles of said cutters or grinders, gear wheels on said spindles engaging
with a stationary gear, a spindle upon which the yoke is mounted, and a crank for
rotating said spindle, whereby a planetary motion of the cutters or grinders is
produced, and a guide for the pencil, substantially as set forth.
5. In a pencil sharpening machine, the combination with a rotary cutter or
grinder, of a guide for the pencil. consisting of two pivoted ☐ shaped levers, a
link connecting said levers, and a spring acting upon said levers, whereby a pencil
inserted between said levers will be so held that its axial centre will pass
through the axial centre of the spindle carrying the cutter or grinder, and
means for adjusting said levers to permit the insertion and withdrawal of a pencil,
substantially as set forth.
6. The combination with a tool carried by a rotating spindle, of a work holding
device consisting of two pivoted levers, a link connecting said levers, and a spring
acting upon said levers, whereby the work inserted betweeu sail levers will be so
held that its axial centre will pass through the axial centre of the tool or its
spindle, and means for adjusting said levers to permit the insertion and withdrawal
of the work, substantially as set forth.
7. In a pencil sharpening machine, the combination with the case B, of a
stationary gear carried thereby, a bearing for a rotating spindle provided with
a yoke carrying two revolving cutters or grinders, said cutters or grinders being

page_text: provided with gear wheels meshing with the stationary gear, whereby a
planetary motion of the cutters is produced, a pencil guide mounted on the
opposite side of the case, and an adjustable supporting bracket for said case,
substantially as set forth.
Dated March 17th 1896
HARRIS & MILLS,
23 Southampton Buildings, London, W.C., Agents.