Improvements in Saws.
Year: 1891

page_text: Date of Application, 23th Dec., 1891
Complete Specification Left, 26th Aug., 1892-Accepted, 28th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Saws.
I JOHN COWDERY MARTIN of 92 Grosvenor Park Camberwell London S.E.
Manufacturer do hereby declare the nature of this invention to be as follows:-
I form thin cutters upon and projecting beyond the ordinary teeth of a saw
after the manner of the cutters of a smooth cutting augur these operating upon
each side of the saw cut, or I produce these cutters separated from the ordinary
wider saw teeth by forming two of every three teeth of a saw with thin knife like
edges of sufficient length of edge sharpened towards the sides of the saw alternately
and extending beyond the third or following tooth which is an ordinary saw tooth
not projecting so far as these and which removes the material between the two
smooth side cuts. For some purposes and materials fine saw like teeth may be
formed upon the thin edged longer teeth.
1
1001
COMPLETE SPECIFICATION.
Improvements in Saws.
I JOHN COWDERY MARTIN of 92 Grosvenor Park Camberwell London S.E.
Manufacturer 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 :-
I form thin cutters upon and projecting beyond the ordinary teeth of a saw after
the manner of the cutters of a smooth cutting augur, these operating upon each
side of the saw cut, or I produce these cutters separated from the ordinary wider
saw teeth by forming two of every three teeth of a saw, with thin knife like edges,
of sufficient length of edge, sharpened towards the sides of the saw alternately, and
extending beyond the third or following tooth, which is an ordinary saw tooth, not
projecting so far as these, and which removes the material between the two smooth
side cuts. For some purposes and materials fine saw like teeth may be formed
upon the thin edge of longer teeth. I do not confine myself to any particular
arrangement of these thin edged projecting cutters relative to the ordinary saw
teeth, as the disposition and form of these.and the distance they project beyond the
ordinary saw teeth, would depend upon the material operated upon, and the speed
at which the saw was driven relative to the speed at which the material was fed
against it. For a comparatively slow speed of the saw, and a comparatively rapid
feed of the material, each tooth would be provided with a cutter projecting from.it.
For a comparatively high speed of the saw, and a comparatively slow feed of the
material, two of the projecting cutting teeth may be arranged between or before
each of the ordinary saw teeth, or one of the projecting cutting teeth may be
placed between each ordinary saw tooth, and I form the cutting edge of the thin
projecting teeth when operating upon soft wood for instance, that while the
advancing edge is slightly chisel shaped, the greatest thickness of the tooth is
towards this advancing edge, in order to avoid undue friction at the sides, and
heating of the saw. For harder woods the bevel or angle of the chisel edge is more
obtuse, until for some hard woods or purposes, the greatest thickness of the cutter
is quite at the advancing edge, and it acts in some measure as a graver, to clear a
passage before it.
When perfect smoothness of the cut is not required, but merely
a finely sawn flat surface with rapidity of cutting, I form the thin projecting cutters

page_text: with very small saw teeth upon their outer edges, so that two fine shallow saw cuts
are produced in the material, one on each side of the saw, the space between these
being cleared by the shorter but more rapidly cutting larger ordinary saw teeth
without lacerating the side surfaces. It is to be understood that the projecting or
longer cutting teeth, are set or spread alternately on opposite sides of the saw, so
as to produce a saw cut slightly wider than the thickness of the saw, and whether
they are formed with smooth cutting edges, or with small saw teeth upon these,
they are to be kept truly in line with each other, or made to work exactly in the
same plane. I prefer to arrange the longer projecting teeth so that two of these
are placed between two of the shorter ordinary saw teeth, and they may be made
to project beyond these ordinary teeth about one sixteenth of an inch more or less,
or sufficiently so to cut off or detach from the side, the portion of material that
would otherwise be roughly torn from the side surfaces, by the ordinary saw teeth
as they advance.
Reference being made to the drawings,
Fig. 1 is a side elevation of a saw tooth when this and the projecting cutter are
formed together.
Fig. 2 is an end elevation of two of these teeth when looking at their edges, one
being behind the other with the cutters upon opposite sides of the saw.
Fig. 3 is a side elevation of the arrangement when two projecting cutting teeth
are placed together, between the ordinary saw teeth, the dotted line shews that
they project beyond these, A. A are the ordinary teeth, B. B are the projecting
cutting teeth; a. a. shews the thicker or advancing edges, b. b. the thinner or back
edges of the cutters.
Fig. 4 shews front view of two of the separate projecting teeth, one being behind
the other.
Fig. 5 shews the arrangement when a projecting cutting tooth and an ordinary
saw tooth are placed alternately.
Fig. 6 shews the form and arrangement when two projecting thin teeth are
between the ordinary saw teeth, the projecting teeth being formed with small saw
teeth upon their thin outer edges.
The references to the dotted lines and letters apply to each figure.
Although the dotted lines are shewn straight in the figures, it is to be under-
stood that the same relative positions and projections are to be retained when
these lines are curved and they form the periphery of circular saws.
I do not confine myself to any exact form of the thin cutters, as the advancing
edge may be thrown back as shewn in the drawings, and more or less sharpened, or
the cutters may be pointed with the advancing edge vertical, or nearly vertical, as
in an ordinary saw tooth.
Having now particularly described and ascertained the nature of my said inveu-
tion and in what manner the same is to be performed, I declare that what I
claim is
1-Forming the teeth of saws with a projecting cutter forming part of the tooth
substantially as described and illustrated.
2-Forming saws with teeth in the ordinary manner intermixed with other thinner
teeth projecting beyond them and acting as cutters upon each side of the saw sub-
stantially as described and illustrated..
3-Forming smaller saw teeth upon the outer edges of the projecting cutters or
thinner teeth substantially as described and illustrated.