An Improved Apparatus for Sharpening and Setting Saws.
Year: 1895

page_text: Date of Application, 19th Sept., 1895-Accepted, 19th Oct., 1895
[Communicated from abroad by PAOLO TOMMARCHI, of Ameglia, near
Genoa, Italy.]
An Improved Apparatus for Sharpening and Setting Saws.
I, WILLIAM PHILLIPS THOMPSON, F.C.S. M.I.M.E. of The Agency for
Foreign Patent Solicitors, 31, High Holborn, in the County of Middlesex, 6, Lord
Street, Liverpool, and 6, Bank Street, Manchester, both in the County of
Lancaster, and Lower Temple Street, Birmingham, in the County of Warwick,
Civil Engineer 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 :-
The apparatus which forms the object of the present application for Letters
Patent is designed to effect the sharpening and setting of saws efficiently and
quickly. It is constructed in the following manner. The motor shaft A of the
machine can be actuated by hand or by power as required, the requisite driving
attachment being keyed to its right hand end (Fig. 2). The said shaft bears at its
other end a mechanism composed of the disc B with crank handle and the cam C
forming a single piece. The said dise B is capable of adjustment, the crank pin D
being movable by means of the screw E by which means the sliding piece G cau
be caused to move with a shorter or longer stroke under the action of the connecting
rod F and consequently to make the file applied in the lower part K of G to move
through a given space with an alternating rectilinear motion. The points of
connection of the piece G with the rod F is adjustable by means of the screw
nut I in the slot L, so that the file when in motion can act throughout its length in
the most direct manner possible.
Each stroke of the file sharpens a tooth and the machine automatically displaces
the saw by one tooth at each stroke.
This movement is obtained by means of the cam C against which is pressed the
little wheel a which imparts an alternating motion to the bar M provided with a
counter weight which maintains the little wheel pressed against the cam. The
bar M is provided with a slot in which is fixed at a suitable point in relation to the
centre of rotation of the bar the point of attachment of the draw bar N for
actuating the wheels O and imparting to the horizontal shaft. P an intermittent
rotary motion of various speeds according to the point of adjustment of N and M.
The shaft P transmits by means of a pair of coned wheels its intermittent rotary
motion unaltered to the little vertical shaft Q which by means of a wheel and
ratchet imparts an intermittent rectilinear motion to the support R in which the
saw to be sharpened is fixed and which moves on, by motions equal to each other
and to the spaces between the teeth of the saw, every time the piece G has attained
the lowest point of its course.
The point b marks the attachment of a second draw bar S actuating the system
of wheels T and the horizontal shaft U which is thereby revolved with an
intermittent motion like that of P. On the shaft U is mounted the disc V which
partakes of its motion and transmits the same by friction to a second disc W in
contact with it. The two discs serve to set the saw whilst it is being sharpened
consequently they must move equally with and through the same distances as the
support of the saw. The frame of the machine is composed of the upright X
bearing the main shaft A the sliding piece G the oscillating bar M and the

page_text: support of the little shaft U. The upright is fixed to the bench Y provided
with feet and which supports the shaft P, the saw holder and the setting
discs. The supports of P are fixed, whilst that of the saw is attached to the
bench which is formed like the bench of a lathe by means of two screw bolts,
so that it is adjustable in order to take saws of any size whether straight, ribbon,
or circular.
When the whole support is displaced it carries with it the coned
wheels mounted thereon so as to maintain always the transmission of the motion
to the little shaft Q. In addition to the adjustment described this support may
have the following: an adjustment in the horizontal direction and parallel to the
plane of the bench by means of screws attached to the plates between which the
saw is gripped in order to regulate with exactitude the part of the tooth which is
to be seized by the setting discs; another adjustment in a vertical direction so as
to arrange the plates exactly opposite the line of contact of the discs. The discs
also are placed in a support adjustable on the bench in order to adjust their
position with regard to the stroke of the file and the upper disc is moreover
adjustable vertically by means of a screw so that it may not crush the saw and
can give the same the desired setting. The part K of the slide G is made long in
order to accommodate two files, one to commence the sharpening the other for the
polishing, and so that the machine can be worked by a right hand or left hand
motion of the shaft A and the motions of the wheels O and T are reversible for
the same object. The setting discs form an important part of the invention of
my foreign correspondent on which this machine is based. These discs are
constructed with a cylindrical portion prolonged as a truncated cone towards the
saw to be sharpened and the surface thereof has projections and depressions of
triangular shape exactly corresponding to the teeth of the saw which engage
therein, like the teeth of gear wheels but with an engagement variable according
to the position of the upper disc in relation to the lower one so that the saw teeth
passing between the discs after sharpening are bent alternately one upwards, the
next downwards to the required extent. The amount of setting is such that
every pair of discs serves for different height and set of teeth; in practice 4 pairs
of discs suffice to set every kind of saw usually in use. The arrangement of the
piece G and crank-disc E is such that any usual kind of file used for saw sharpening
is applicable with them.
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
The apparatus for sharpening and setting saws substantially as hereinbefore
described and illustrated in the accompanying drawings.
Dated the 19th day of September 1895.
W. P. THOMPSON & Co.,
Agents.