An Improved Saw Sharpening Machine.
Year: 1894

page_text: Date of Application, 13th Aug., 1894-Accepted, 22nd Sept., 1894
An Improved Saw Sharpening Machine.
A communication by FRIEDRICH SCHMALTZ, of 10, Domstrasse, Offenbach-on-
the-Main, in the Empire of Germany, Manufacturer.
I, GEORGE CECIL DYMOND M.I. Mech. E., of The Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6, Bank Street, Manchester,
both in the County of Lancaster and 323 High Holborn in the County of
Middlesex, Patent Agent, 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 for its object a machine by means of which the teeth of
frame, band, circular and other saws, or cutters, may be automatically sharpened
by means of a rotating emery disc. The edges of the separate teeth are alternately
sharpened obliquely both on the underside of the teeth, as well as on the back of
the teeth, so that each tooth receives a point with a knife edge, in consequence
of which the cutting capabilities of a saw sharpened in this way are greatly
increased.
By this invention it is possible periodically to adjust the saw and the emery disc
to one another at an inclination, in an extremely simple manner, in fact by simply
allowing the emery disc when the saw is fixed to turn or oscillate on a vertical axis
which lies outside the plane of the emery disc, the latter being directed either
vertically or angularly against the saw. Owing to the fact that the emery disc
which rotates outside its axis of suspension turns to the right and left against the
saw travelling in a carriage underneath it, it does not always bear against the saw
with the same part, but according to its position with a part lying outside the
centre of its periphery, in fact first to the right and then to the left of it whereby
the under edge of the teeth as well as the rear edge of the teeth, is sharpened to a
bevel edge.
These improvements are shown on the two sheets of the accompanying
drawings.
On Sheet 1, Figures 1, 2 and 3 show the method for sharpening at various
inclinations, which sharpening only takes place on the under edge a of the teeth of
the saw S, and the same takes place by the emery disc only engaging the teeth
with the centre of its periphery, that is to say when the plane of the disc and the
axis of suspension lic in a common plane.
In Figures 4, 5 and 6, on the other hand, the method for sharpening the saw S at
various inclinations is shown, in which sharpening process both the under edge a
and also the rear edge of each tooth presents an inclined surface. This bevel
sharpening is effected by the emery disc being arranged in the emery disc arm
outside the axis of its point of suspension, as shown in Figure 4. As the suspended
emery disc turns alternately on its point of suspension to the right and to the left
it comes in contact with the saw S lying beneath it with a part of its periphery
which lies at a little distance to the left or right of the centre of the periphery and
not with the centre itself as the saw and the axis of suspension of the emery disc
lie exactly in one plane (Figures 5 and 6), in consequence of which all the surfaces
of the saw teeth are operated on at an inclination. This operation at an inclination
is increased, the further the emery disc is removed from the plane which must be
taken through the axis of suspension of the emery disc, that is to say, the more
eccentrically the emery disc is arranged to its axis of suspension.

page_text: periodically moved up and down in order to render it possible, by suitably moving
forward the saw for all the teeth to come one after the other in contact with the
disc.
emery
On Sheet 2 such an automatically working saw sharpening machine is shown
with its various mechanisms necessary for carrying out the bevel sharpening
hereinbefore mentioned.
Figure 7 is a side view of the machine;
Figure 8, a plan view;
Figure 9, an end view of the same;
Figures 10, 11, 12 and 13 are enlarged details of parts of the machine.
The emery disc 1 employed for sharpening the saw teeth, the spindle of which
disc is arranged in a stirrup or fork 2 which in its turn is suspended in its vertical
axis from an arm 3 counterbalanced by a counterweight 3* receives its rotation by
means of a cord from the driving pulleys 4. These driving pulleys 4, one of
which is fixed and the other loose on the shaft, are arranged in a double frame or
support 6 suitably fixed on the under frame 5 of the machine. The frame 6 also
holds centered between two points the arm 3 carrying the emery disc to which the
pulleys 4 impart motion by means of further cord or belt pulleys arranged on the
same spindle, a motion which is transmitted also to all the other parts of the machine.
On one side of the supporting frame 6 is a projection 7 in which a sliding piece 8,
Figures 7, 8 and 10, may be worked up and down by means of an adjusting screw 9,
elbow lever 10 and connecting piece 10x in order to bring the saw support 8×
arranged on the front of this sliding piece 8 together with the saw S to a suitable
height to the emery disc.
In order to allow the sliding piece 8* to move forward or backward to correspond
with the varying thickness of the saws S which are to be sharpened and which are
attached to the bar 11 connected with the sliding piece 8, a slot is provided in the
side of the projection 7 (Figure 8). In this slot there is arranged an elbow
lever 12 connected with the sliding piece 8. This lever may be adjusted by means
of an adjusting screw 13 turning in the machine frame so that a movement forward
or backward of the sliding piece 8 and of the projection or support 8* is rendered
possible to suit saws of varying thickness. The bar 11 for fastening the saws
which are to be sharpened, is firmly connected by one of its ends with the sliding
piece 8 and its other end works freely in a socket 14 arranged on the machine
frame 5. Circular saws are also screwed on a projection 15 which by means of a
sliding piece 16 may be adjusted up and down or fixed on the bar 11. Frame and
band saws on the other hand are fixed in a fork 17, Figure 12, which may also be
adjusted up and down or fixed on the bar 11 by means of a slide piece 17. Owing
to the fact that all the saws which are to be sharpened are fastened on the bar 11
which can be adjusted as hereinbefore described it is possible by means of the
adjusting screw 9 to at any time obtain the most exact supplementary adjustment
of the saws against the emery disc to meet the wearing away of the latter.
The mechanism for pushing forward a saw which is to be sharpened, is operated
from a spindle 18 arranged on the frame which spindle is driven from a small belt
pulley 4* firmly mounted on the shaft of the driving belt pulleys 4.
On this
spindle 18 there are several eccentrics or cams, one of which operates the pushing
forward of the saw, another the movement to the right or left of the emery disc
and another the up or down movement of the emery disc arm together with the
disc. The cam 19 which is employed for pushing forward the saw S is a double
cam so that at a single revolution of the spindle 18, this cam produces a double
operation of the cam lever 20 with which it engages. A lever 21, Figures 8 and 11,
which is influenced by a weight 21* rests on this cam lever 20. This lever 21 may
be adjusted to the right or to the left on its axis of rotation 22 and may be fixed
firmly by means of a clamp screw. A lever 23, Figures 7, 8 and 11, is also
connected with the revolving spindle 22, on which lever the actual adjusting
pawl 24 is mounted, which engages in the saw teeth and thus moves forward the

page_text: saw one tooth each time on the up and down movement of the cam lever 20 by
means of the cam 19. In order to enable the pawl 24 to be exactly adjusted as
regards the distance of the teeth from point to point in saws of various sizes, the
lever 21, provided with a counterweight 21, is as already hereinbefore stated so
arranged on its axis of rotation 22 as to be adjustable to the right or to the left, so
that when this lever is adjusted on its axis 22 to the left, Figures 7 and 8, the
lever 21 together with the lever 23 and the pawl 24 describe a greater course on
the cam lever 20 moving up and down than is the case when the lever 21 is
adjusted to the right on the axis 22. In this case, the lever 21 approaches nearer
to the point of rotation of the cam lever 20 and consequently undergoes a smaller
inovement outwards.
In order when sharpening a saw to enable the under edge of each tooth as far
as possible to be brought in contact with the emery disc, a set screw 25, Figures 7,
8 and 11, is arranged in the lever 21, which set screw when turned forward or
backward raises or lowers the lever 21 and thus causes the pawl 24 to engage sooner
or later in one tooth space, and to push forward the saw. As however the pawl 24
only engages in one tooth space at a time, and as this movement is made dependent
for the various sizes of saws on the adjustment of the lever 21 on its axis of
rotation 22, the earlier or later engaging of the pawl 24 in one tooth space is
rendered possible by the mere adjustment of the set screw 25, and thus also an
earlier or somewhat later adjustment of the saw, or a greater or smaller moving
forward of the separate teeth of the saw over the emery disc is effected. If,
however, the separate teeth are not pushed out so far over the emery disc 1, the
emery disc must naturally engage the under edges of the teeth and operate
thereon, or grind them. In other words if the set screw 25 be turned to the left,
the pawl 24 also moves to the left, and consequently does not push the saw so far
forward. The cutting under edge of each separate tooth then comes more within
reach of the emery disc and is more worked by it than when the set screw 25 is
turned to the right, as in the latter ease the emery disc works the under edge of
a tooth less.
The cam 26 which is also mounted on the spindle 18 and is also a double cam,
operates the up and down movement of the emery disc 1 by the emery disc arm 3
being extended beyond its point of rotation and bearing with this extension
against the cam 26 in order to be influenced by this latter. And as the end of the
arm 3, on which the emery disc 1 which is revoluble on a spindle is suspended, acts
as a counterweight against the extension of the arm 3, the emery disc arm also
always remain in contact with the surface of the cam 26 belonging thereto. The
position of the cam 26 relatively to that of the cam 19 is such that the former is
set a little in advance of the latter, Figure 13, in order to render it possible for the
emery disc 1 to have commenced to quit one tooth space before the mechanism for
the pushing forward of the saw commences to act.
A third cam or eccentric 27 is also mounted on the spindle 18 and operates the
elbow lever 28 which is arranged on the machine frame 5 and provided with a
counterweight, and simultaneously moves the emery disc 1 which is connected with
it by means of the draw bar 29, Figure 7, and is revoluble on its axis of
suspension, for whilst the arm of the elbow lever 28 on which the counterweight
is mounted is raised by the eccentric 27, the draw bar 29 which is connected with
the other arm of this elbow lever, turus the emery disc on its axis of suspension,
and brings it into an inclined position to the saw S which lies beneath it, whereby
a grinding at an inclination of the surfaces of the teeth of the saw in question,
more particularly the under edges of the teeth, is brought about. If the counter-
weight on the elbow lever 28 in consequence of the further rotation of the eccentric 27
again draws back this lever, or brings it into another position, the emery disc is
drawn by the mechanism connected with it so far in an opposite inclined position
to the saw S that the under edges of the next following tooth are sharpened in an
opposite way to those of the previous tooth. The reversal of the emery disc from
the one position to the other is however no sudden one, but takes place gradually.

page_text: It commences shortly after the emery disc has commenced to move away again, and
is completed as soon as the same has ground out one tooth space.
The emery disc, and with it the arm 3 goes down and up and then only the
rotation of the emery disc takes place, the latter is turned as soon as it has quitted
a tooth. As however in most saws the teeth are set, that is to say, are alternately
arranged to the right and left of the plane of the saw blade, Figure 14, by the
above described machine there is obtained also a certain grinding at an inclination
of the backs of the teeth, if the emery disc 1 be mounted and allowed to run in
the plane of the axis of suspension instead of outside the same, as shown in
Figure 14. If, however, the backs of the teeth are to be sharpened at a greater
inclination, the disc is arranged more outside the plane of its axis of suspension in
the arm 3; and in order that the under edge of each tooth shall always be suitably
sharpened, the emery disc is further arranged in a support frame in such a
way that its plane is somewhat inclined out of the horizontal, as shown in
Figure 9.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. An improved saw sharpening machine for grinding at an inclination the rear-
and under edges of saw teeth, consisting in the emery disc being so suspended
in an arm suitably arranged on the machine frame, that this disc lies in a plane
outside the axis of suspension of the same, whereby on the periodic reversal of
the emery disc the teeth of the saw which are to be sharpened, are worked upon
by a part of the disc which lies outside the centre of the periphery of the disc,
substantially as hereinbefore described and shown.
2. An improved saw sharpening machine of the kind described in Claim 1,
characterized by a spindle (18) arranged on the machine frame and provided with
three cams or eccentrics (26, 27 and 19), which spindle by means of an arm (3)
moves up and down the emery disc (1) which is revoluble on its vertical axis, a lever
mechanism (28 and 29) connected with the emery disc, which lever mechanism
moves this disc periodically to and fro on its vertical axis (2); and a lever
mechanism (20, 21, 23 and 24) arranged on the frame of the machine, which lever
mechanism pushes forward the saw each time to the extent of one tooth, so that
by the combined action of these above mentioned arrangements, on the one hand
on the emery disc (1) and on the other hand on the saw which is to be sharpened,
each tooth of the saw (which is held fast) is ground at an inclination on its rear
and under edges, substantially as herein before described and shown.
3. In a machine of the kind described in Claim 2, a lever mechanism for moving
forward the saw, consisting of the cam lever (20) the lever (21) which is
adjustable to the right and left on a spindle (22) and is provided with set screw (25)
and counterweight (21×) and the lever (23) which is firmly connected with this
spindle (22), together with the pawl (24) for pushing forward the saw, (which pawl
is movably connected with the lever 23) with the object of regulating the forward
movement of the saw, and the operation of the emery disc on the teeth, substan-
tially as hereinbefore described and shown.
4. In a machine such as described in Claim 2, a spindle (18) with the double
cams (19 and 26) arranged thereon, and a simple cam or eccentric (27) with the
object of producing a movement of the emery disc twice up and down, as well as a
movement to and fro of the pawl (which moves forward the saw) against the
teeth of the saw during one rotation of the spindle, substantially as hereinbefore
described and shown.
D 14 1
1004