Improvements in and relating to Saws.
Year: 1895

page_text: Date of Application, 2nd Sept., 1895-Accepted, 5th Oct., 1895
COMPLETE SPECIFICATION.
Improvements in and relating to Saws.
I, CHARLES HENRY DOUGLAS, a citizen of the United States of America,
residing at 1028 Jackson Boulevard, in the City of Chicago, County of Cook, and
State of Illinois, one of the United States of America, Mechanical 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:-
My invention relates to an improvement in saws, and more particularly in circular
saws, and the object is to provide a saw that will cut easily and accurately through
timber of every quality and kind without scoring or roughing the walls of the
kerf, and without consuming as much power to do a given amount of work, as
other saws require.
I attain this object by the form and construction of the saw teeth hercia
described, and illustrated in the accompanying drawings.
Figure 1 is a small portion of a circular saw showing a few of the improved
teeth.
Figure 2 is an edge view of the same.
Figure 3 is an enlarged view of one tooth.
Figure 4 is a cross section through line x-x of Figure 3.
Similar letters refer to similar parts throughout the several views.
The teeth are so formed that there is a clearance on the back or outer edge of
each tooth of less than five degrees from the point or cutting edge to the heel,
which causes them to cut or produce shavings instead of breaking the chip into
sawdust. On one side of cach tooth there is a flat rib A, which extends from the
cutting point to the heel, and on the opposite side of each is a bevel B. These
ribs are on alternate sides of the teeth and project about one-hundredth of an inch,
more or less, according to the size or thickness of the blade. The object of the
ribs is to widen the cutting points of the teeth, and also to present a flat surface
against the walls of the kerf as a steadier of the saw while cutting.
The form of the teeth is such that the front or cutting end of each tooth is more
easily sprung sideways than the heel, and therefore if the rib was made prominent
at the heel as at the point of each tooth, the point would spring away from the
wall of the kerf and leave all the pressure against the heel. To overcome this
result, and fully compensate for the unequal side spring at the two ends of the
tooth, the rib A is made tapering from the point to the heel, or more prominent at
the point than at the heel of each tooth, as shown in Figures 2 and 3. By this
device the rib A is caused to ride against the wall of the kerf with equal pressure
at both ends, and the friction that would otherwise ensue froin an unequal pressure
upon the face of the rib is thus avoided.
The angle required to cause rib A to come level with the wall of the kerf and
in exact line with the cut when in actual work, does not exceed one degree, and in
most kind of timber, should be much less, to avoid cutting or scoring the timber.
In my former United States Patent on saws, No, 431,510, I have described a
rib on the side of the tooth that is level with the face of the saw, or as prominent
at one end as the other. The taper form of rib herein described is a great
improvement over the former rib, as it causes the saw to cut more easily and run
cooler, while it accomplishes just as smooth work.
I do not limit my invention to any special form of saws. It is equally useful on
band, straight, or circular saws, either solid or inserted teeth.

page_text: 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. A saw provided with teeth so formed that the backs or outer edges of the
teeth have a clearance of less than five degrees angle from the line of cut, and on
the sides of which there are ribs A, A, which extend from the cutting points to or
toward the heels, which ribs are more prominent at the points than at the heels of
the teeth, and form an angle with the face of the saw blade of less than one degree,
substantially as and for the purpose specified.
2. A saw tooth that is provided with a rib A on one side, from the point of said
tooth to or toward the heel, which rib is thicker or more prominent at the point
than at the heel, substantially as and for the purpose specified.
Dated this 2nd day of September 1895.
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.