Improvements in Safety Devices or Guards.for Circular Saws
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Safety Devices or Guards.for Circular Saws,
I, WILLIAM ALEXANDER WEBSTER, of 96, Miles Street, Preston, in the County
of Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:
My said invention relates to improvements in guards for circular saws used
for the prevention of accidents as is well understood.
In constructing a circular saw guard in accordance with my invention I pro-
vide a canopy or shield adapted to entirely enclose the portion of the circular
saw protruding above the saw bench. This canopy may consist of two metallic
plates, lined with wood, of semi-circular shape or thereabouts, one disposed on
each side of the blade and connected together at the upper edges by a plate
or other suitable means. The space between the edges of the shield at the lead-
ing end of the saw may be uncovered so as to afford inspection of the saw disposed
within the semi-circular plates.
1
I secure a standard to the saw bench which standard carries a projecting arm
the outer end of which is provided with a bearing for a bar or rod disposed
parallel with and a suitable distance above the circular saw. To each end of this
parallel rod I loosely pivot a lever the other ends of the levers being also loosely
pivotted to the saw guard. The saw guard can thus be raised and lowered by
means of these levers parallel with the saw bench. Normally the weight of
the parts, counter-balanced by means of a suitable weight or spring, ensures that
the guard falls into its lowest position upon the saw bench and thus shrouds
the circular saw. When work is advanced to the saw, the material to be cut
coming into contact with the guard, raises the same by reason of the loosely
pivotted levers, the work raising the guard a sufficient height only to permit
of the passage of the work. When the cut has been made and the work with-
drawn the saw guard automatically falls and again shrouds the saw, requiring
no attention for that purpose on the part of the attendant. It will thus be seen
that an. important feature of my invention lies in the fact that the guard does
not require adjusting for the various sizes of material operated upon but is self-
adjusting, to any size or thickness of material capable of being cut by the saw,
and is each time raised only so much above the bench as will permit of the
passage of the work. To facilitate the raising of the guard by the incoming
material I provide the guard with an anti-friction bowl or bowls or other suitable
means to effect the object.
The anti-friction bowl is mounted in close proximity with the saw and is pre-
ferably of wood so as not to injure the saw by accidental contact therewith.
Although the saw is completely encased by the guard before the work is fed
to the saw, yet when the guard is raised and thrust rearwards by the material
being cut, a small portion of the periphery of the saw is bared so that the work-
man can readily observe the cut and is enabled to accurately perform his work
without the liability of spoiling the work by inaccurate cutting.
The guard or canopy is made large enough to accomodate the largest circular saw

page_text: used in the bench, and to readily adjust the guard to the smaller sizes the parallel
bar to which the swinging levers are pivotted is made adjustable so as to be slid
in its bearings. A convenient method of doing this would be to form or provide
the bar with rack, teeth with which engages a pinion operated by a hand wheel.
When a saw of smaller diameter is mounted in the saw bench the guard-can thus
be readily slid towards the rear of the bench until the fore-foot of the guard is
arranged in satisfactory justaposition to the teeth of the saw. This adaptability
of adjusting the one guard to various sizes of saws is an important feature of
my invention.
To remove the guard whilst changing the saw, or whilst requiring access to it
for any purpose, the guard is raised sufficiently high to clear the top of the saw
and is then maintained in its raised position by means of a suitable catch or the
like.
Or I might arrange the arm upon the standard which carries the parallel bar
so as to be capable of turning when required and thus swing the guard bodily
away from the saw.
I may combine with the guard the usual rear guard blade and secure the two
together so as to mutually support and strengthen each other.
The method of mounting the guard might be varied.
For instance, the guard might be provided with studs or anti-friction bowls
engaging with suitable slots or ways provided in conveniently arranged adjust-
able brackets so that the material being fed to saw would raise the guard by
means of the bowls engaging with the slots or ways, the guard being again
automatically returned to its normal position on the withdrawal of the work.
I, WILLIAM ALEXANDER WEBSTER, of 96, Miles Street, Preston, in the Count
of Lancaster, Engineer, do hereby declare the nature of this invention and
what manner the same is to be performed to be particularly described and asce
tained in and by the following statement and accompanying drawings:-
-
My said invention relates to improvements in guards for circular saws us
for the prevention of accidents as is well understood.
The accompanying sheet of drawings clearly illustrates my invention.
Fig. 1 is a side elevation of my improved saw guard.
Fig. 2 is an end elevation thereof looking in the direction of the arrow.
Fig. 3 is a plan and
Figs. 4 and 5 are detached detail views.
In constructing a circular saw guard in accordance with my invention I pr
vide a canopy or shield a adapted to enclose the portion of the circular saw pr
truding above the saw bench b. This canopy a consists of two side cheeks
of wood secured to a metallic frame a², preferably of aluminium, of semi-circula
shape or thereabouts. One of the wooden cheeks is disposed on each side
the blade the top edge of the saw being covered by the metallic frame ².
If desired the side cheeks of the canopy a may be formed from sheet met

page_text: lined with wood, or such side cheeks may be made from wire netting or other
perforated material so that the saw can be seen through the perforations.
The space between the side of the shield at the leading end of the saw may be
uncovered so as to allow the saw teeth to project beyond the front edge of the
shield when the shield is lifted by the passing work thereby allowing the work-
man full view of the saw teeth entering the work. One of the side cheeks a¹
may be cut away as shown at as so as to allow the fence or gauge to come close
up to the saw when cutting thin material.
To carry the saw guard, I secure a standard c to the saw bench 6 which
standard carries a projecting arm d to the outer end of which is secured a
bracket e provided with a bearing for a bar or rod f disposed parallel with and
a suitable distance above, the circular saw bench b.
In the plan view Fig. 3 the standard c and arm d are removed so as not to
obscure the parts. To each end of this parallel rod or bar f I secure a bracket g
to which levers h h are loosely pivotted.
The other ends of the levers h are also loosely pivotted to the saw guard. The
saw guard can thus be raised and lowered, by the swinging of these levers,
parallel with the saw bench. Normally the weight of the parts, counter-balanced
by means of a suitable weight i, or it might be a spring, ensures that the guard
falls into its lowest position upon the saw bench and thus shrouds the circular-
saw. To prevent the guard at times falling too far forward so as to come into
contact with the teeth of the saw I provide an adjustable stop s as shown in
Fig. 3 which acts to limit the forward movement of the canopy a..
When work is advanced to the saw material to be cut coming into contact
with the guard, raises the same, the parallel levers h h being swung upon their
pivots, the work however only raising the guard a sufficient height to permit
of its passage. When the cut has been made and the work withdrawn the
saw guard automatically falls and again shrouds the saw, requiring no attention
for that purpose on the part of the attendant. It will thus be seen that an
important feature of my invention lies in the fact that the guard does not require
adjusting for the various sizes of material operated upon but is self-adjusting to
any size or thickness of material capable of being cut by the saw, and is each
time raised only so much above the bench as will permit of the passage of the
work. A gauge j slidably mounted in the bracket g may be secured by means
of a pinching screw k to regulate the maximum height to which the guard may be
raised. To facilitate the raising of the guard by the incoming material I pro-
vide the guard with anti-friction bowls or other suitable means to effect the
object.
The anti-friction bowls are mounted in close proximity with the saw and are
preferably of wood so as not to injure the saw by accidental contact therewith.
One only of such bowls may be used if desired.
The guard is adjusted so that the saw is completely encased before the work
is fed to the saw, but when the guard is raised and thrust rearwards by the
material being cut, a small portion of the periphery of the saw is bared so that
the workman can readily observe the cut and is enabled to accurately perform
his work without the liability of spoiling the work by faulty cutting.
This is shown more clearly in Fig. 4 the lowest position of the guard being
shown in dotted lines.
The guard or canopy is made large enough to accomodate the largest circular
saw used in the bench, and to readily adjust the guard to the smaller sizes, the
parallel barf to which the swinging levers h h are pivotted, is made adjustable
so as to be slide in its bearings. In Fig. 1 the guard is shown adjusted for the
largest saw of the series. When a saw of smaller diameter is to be mounted
in the bench, the screw m of the bracket e which engages with a groove f¹ in
the rod f is slackened and the rod f and attached saw guard can then be slid
in the direction of the arrow, Fig. 1, to accurately adjust the guard so that it
barely covers the teeth at the leading end of the saw,

page_text: .
Thus, immediately; the guard is raised a small portion of the teeth of the saw
is bared as, before, described so, that the workman can observe the cut. Another
convenient method of adjusting the. guard backwards or forwards would be to
form or provide the, bar with rack teeth engaging with a pinion operated, by
a hand wheel. This adaptability of adjusting the one guard to various sizes of,
saws, is an important, feature of my invention.
To remove, the guard, whilst changing the saw, or whilst requiring, access to it
for any purpose, the guard is raised sufficiently high to clear the top of the saw
and may be then maintained in its raised, position by means of a suitable, catch
or the like.
Or I might arrange, the arm. d. upon the standard c. which carries the.parallel
bar so as to be capable of turning, when required and thus swing the guard.
bodily, away from the saw.
Imay combine with the guard the usual. rear guard blade or riving knife,
although this is not essential to the successful working of the guard.
The method of mounting, the guard might be varied.
.case
For instance the standard c and arm d may be dispensed with., In this ca
the bracket e. forming a bearing for the bar f is secured by means of an angle
piece, n, to a wooden,. or, it, might be metallic,, beam or bar o secured to, and
pendent, from, the roof of, the, workshop.. This arrangement is shown in Fig. 5..
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
1 claim is:-
The improved saw,. guard consisting of a canopy carried by, parallel levers
pivotted to a bar, arranged above, the saw bench and adjustable thereon, to pro-
vide for varying diameters of circular saws, the canopy being provided with an
anti-friction, bowl or bowls and counterbalanced, the whole arranged and acting
in the manner and, substantially as described and shown.
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