Improvements in Guards for Circular Saws.
Year: 1898

page_text: Date of Application, 21st Sept., 1898
Complete Specification Left, 21st June, 1899-Accepted, 5th Aug., 1899
Improvements in Guards for Circular Saws.
I, THOMAS THORNTON, of Margaret Street, Bury, in the County of Lancaster,
Joiner and Builder, do hereby declare the nature of this invention to be as
follows:
-
This invention is designed to provide a reliable and effective guard for circular
saws which can be readily adjusted to any size of saw and will be automatically
raised to admit the work.
The hood or part of the guard that covers the saw is mounted upon a stay rod
or arm or an upright pillar or support upon which it is capable of being adjusted
vertically and held in position by a set-screw. The hood or cover is attached
to the stay rod or arm by bolts or screws and is adjustable thereto by means of
a slot or otherwise.
The hood or cover is made in two parts with the front or free end pivoted to
the other part so as to be capable of being swivelled or raised and lowered upon
its pivot.
This loose or pivoted part is made of ✓ or other convenient shape with an arın
or lever projecting therefrom to which is connected a connecting rod or link by
the movement of which the end of the cover is raised or swivelled, a suitable
lever being provided for operating the connecting rod.
This lever is pivoted on the pillar or other fixed centre with a rod projecting
therefrom which in turn is connected to a second lever pivoted to the saw bench
or to the fence. This second lever is so placed that when the timber is pressed
against it it is moved about its pivot, it raises the end of the hood to admit the
work below it and falls again when the work has passed through. The connect-
ing rod is connected by means of pins, pin-holes and slots to allow of adjustment
for different diameters of saws.
An adjustable extension piece of either wood or metal of U or other conveni-
ent shape is attached to the pivoted end of the cover or hood to cover the teeth
of the saw at the front. This extension piece may be straight or curved and of
different sizes to suit different diameters of saw.
In a modification the operating levers and connecting rods may be placed
beneath the saw bench with a crank and pulley or other device for transmitting
the movement to the pivoted end of the hood or cover. The pulley and arm are
locked together with a hinged catch and the operating lever is placed in a slide
or groove so that it may be adjusted for different sizes of saws.
Dated this 20th day of September
1898.
WM. P. THOMPSON & Co.,
6. Bank Street, Manchester, Patent Agents.

page_text: the catch or lever G by a cranked arm or lever M which is pivoted to the
movable sleeve or collar m on the pillar F. The lever M and connecting rod H
are operated by the raising of the catch or lever G.
At the other end the connecting rod H engages the swinging arm K pivoted
to the pivoted link on a sleeve or collar on the horizontal arm B. The end
of the rod His notched at h which falls over a pin in a swivelling bracket k
on the arm K. The arm is provided with a number of holes into one of which
the shank of the bracket fits as the position of the arm K and sleeve kare
altered or adjusted.
The outer end of the swinging arm K is connected to the extension piece d of
of the front shield D by the link L.
The pillar F is attached to or supported by the fence N so that the lever G
is moved along with the fence. The lever is held at any desired height by the
pin g and may be moved laterally by the spindle g'.
In cases where the fence is not required or is removed for cross-cutting the
front shield may be fixed and held at any height by being clamped to or on its
pivot by a hinged nut or set-screw.
The back shield C which is raised by the direct pressure or action of the tim-
ber upon it carries a projecting rod or bar e extending beneath the connecting
rod H and when the shield is raised this bar rises with it and lifts the notch h
out of engagement with the pin h¹ thereby disconnecting the front shield D
from the connecting rod and catch or lever G.
In the modification shown in Figs. 8 and 9 the rod or spindle g¹ is extended
to carry two catch levers G G¹ which render the apparatus more suitable for
round timber or timber with an uneven surface.
In Figs. 10 and 11 the catch lever G is pivoted on the stud or spindle g¹ car-
ried by the crank lever M³ which forms part of or is attached to a bevel wheel G
by which a second bevel wheel g operated. The horizontal connecting rod H
is pivoted or hinged to the second bevel wheel g² and is moved to and fro thereby.
In Figs. 12 and 13 the catch lever G is placed upon an upright spindle G³
which is rotated in one direction by the pressure of the timber upon the catch
lever and in the opposite direction by the spring g³. The horizontal connecting
rod His pivoted to the arm or lever by a swivelling bracket m. In this modifica-
tion the connecting rod H is provided with a notch h and engaging pin h¹ at
the operated end and as the arm M is rotated the end of the horizontal lever
slides upon the inclined pin M2 and is lifted up and released thereby.
The front and back shields C and D may be made of metal as in Fig. 1 or
of wood as in Figs. 14 and 15 shod with metal tips. The front shield may slide
in the bracket to adjust its length. The bracket may be pivoted to a link
or swinging arm d³ as in Fig. 16 instead of direct to the bracket E and be raised
over a pulley or runner e¹.
In another modification the operating levers and connecting rods may be
placed beneath the saw bench with a crank and pulley or other device for trans-
mitting the movement to the pivoted end of the hood or cover. The pulley and
arm are locked together with a hinged catch and the operating lever is placed
in a slide or groove so that it may be adjusted for different sizes of saws.
When the guard is at rest the front and back shields (and D rest upon the
saw bench in the position shown to cover or protect the saw preferably at one
side as shown though they may be placed in the direct line or plane of the saw
if desired. The timber as it passes to the saw engages and lifts the catch or
lever G thereby operating the crank and lever M the connecting rod H swing-
ing arm K and link L and raising the front guard D to permit the timber
reaching the saw. The timber as it passes beyond the saw raises the back shield C
which raises with it the rod or bare lifting the notch h of the rod H out of
engagement with the pin h¹ thus releasing the front shield D and leaving it
free to fall into normal position again as soon as the timber passes from beneath
it.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. A guard for circular saws constructed with a front shield pivoted to a
supporting bracket and raised by the action of the work upon a catch or lever
operating upon a crank arm or lever connected to the shield by a connecting rod
and link substantially as described.
2. In a guard for circular saws the combination with the front and back
pivoted shields of a pivoted catch or lever (such as G) against which the work
comes in contact a crank arm (such as M) on stationary pillar operated thereby
a connecting rod (such as H) a pivoted swinging arm (such as K) with which the
end of the connecting rod engages, a link (such as L) and a rod (such as e)
attached to the back shield by which the connecting rod H is disengaged
from the swinging arm K substantially as and for the purpose described.
3. A guard for circular saws having the several parts constructed and arranged
in combination substantially as described and shown.
Detod
1441
T
1000
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.