Year: 1886

page_text: I MARTIN DAVID WISCHKER, of N° 32 Mühlendamm, Riga in the Empire of
Russia, Carpenter 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 relates to the construction of an improved fret-sawing machine
and the invention consists mainly in a novel arrangement of guides as hereinafter
described for guiding or regulating the motion of the saw, allowing a much thinner
and smaller saw to be employed than hitherto and without the saw being in
tension.
In order to enable my invention to be fully understood I will describe the same
by reference to the accompanying drawing in which figure 1, represents a vertical
sectional elevation of a fret sawing machine constructed according to my invention
the saw being shewn in its working position; figure 2, is a side elevation partly in
section of part of the same; figure is a detached sectional view of part of the
machine shewing the saw raised out of its working position; figure 4 is plan of
the table of the machine and figure 5 is a horizontal section on line A, B of
figure 3: Similar letters in all the figures represent similar parts.
For the purpose of my invention the guides a and r, for the saw c, are arranged
above and below the work so that they shall be close to the upper and under
surfaces thereof when the machine is adjusted as hereinafter described; the saw
is connected to a rod d, by a projection e formed on the saw c, and fitting in a
corresponding recess f, in the rod d. The other end of the saw c, is free as shewn
in the drawing. The rod d, carries at its upper end a crank shaped piece or hook g,
in which engages a crank pin h, fixed in a disc i, mounted on the end of the
driving shaft j, of the machine revolving in bearings one of which is shewn at k,
figure 2, so that when the shaft j, is rotated in a right hand direction a to and fro
movement is communicated to the saw; l, figure 1, is a fly-wheel on the other end
of the shaft j, and m, is a driving pulley operated by means of a band or cord n,
from a treadle not shewn in the drawing or by other suitable means.
The rod d, is guided in its vertical motion partly by means of the hollow guide
or sleeve a, secured to the frame A of the machine at o, o, and surrounding the
said rod as shewn in figure 5. The guide or sleeve a, is formed with an interior
groove p, in which the saw c, is guided the teeth of the saw being placed in a
direction away from the groove p. The saw c, is further guided by means of a
notch q, shewn clearly in figure 4 formed in a steel plate r, let into the tables, of
the machine and screwed thereto.
The distance between the table 8, and the lower part of the upper guide a, can
be altered when required to suit the thickness of the work being operated upon by
means of a screw t working in a bracket u, fixed to the bench v, or other support

page_text: for the machine; the screw t, is operated by a hand wheel w, and carries the
table 8, at its upper end the table being prevented from rotating with the
screw. by means of projections x, x, thereon sliding in grooves or guides y, y, in
the bracket u.
In the centre of the moveable table 8, is formed a channel or opening z, provided
at its underside with a shoot or outlet a¹, serving for the escape of the saw dust
which channel or opening 2, is of sufficient depth to allow of the downward motion
of the saw c.
The underside of the cranked piece or hook g, has a curved surface b¹, against
which the crank pin h bears and over which it moves when the shaft j, is rotated
towards the left hand whereby the saw c, can be raised sufficiently to be withdrawn
from the work being cut as shewn in figure 3 which represents the parts in the
position they occupy when the saw has been so raised; is the usual hole in the
table 8, through which the saw c, works.
When the machine is required to be used for cutting fret work which has to be
commenced from any other part of the material than the edges thereof suitable
boring mechanism is connected with the machine.
The improved fret saw machine can be arranged to be operated by hand foot or
power and all the various kinds of work usually performed by means of tension
fret saws can be performed by this machine.
To make use of a machine of this construction the saw c, being raised in the
position shewn in figure 3, the work to be cut is placed upon the table 8, which is
then raised by means of the screw t, and hand wheel w, until the upper surface of
the work nearly touches the lower end of the guide a; the saw c, is then lowered
into working position by rotating the shaft towards the right hand as indicated by
the arrow in figure 3, the saw being guided in the groove p, of the upper guide a,
and in the notch q, of the lower guide or plater (as shown in figures 1 and 2) out
of which notch q, the lower or free end of the saw does not come when in opera-
tion. By this means the saw is guided without risk of its becoming broken or bent
and without requiring any tension to be placed thereon. When the work is
finished the shaft ), is rotated in a left hand direction so as to again raise
the saw c.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. In a fret-sawing machine the herein described arrangement of upper and
lower guides for guiding or regulating the saw in its upward and downward
motion substantially as and for the purpose herein before described and represented
in the accompanying drawing.
2. In a fret sawing machine the combination with upper and lower guides
such as a and r, of a saw arranged to be operated without tension being placed
thereon substantially as hereinbefore described and represented in the accompanying
drawing.
3. The improved fret sawing machine hereinbefore described and represented in
the accompanying drawing.