BOITE A ONGLETS POUR SCIE ELECTROMECANIQUE PORTATIVE

MITER BOX FOR PORTABLE POWER SAW

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
A miter box for a portable circular saw is disclosed,
comprising a flat rectangular base and a pair of upraised, parallel
and spaced-apart longitudinal guide rails. One of the guide rails is
rigidly secured to the base while the other can be laterally adjusted.
A fence to align a board is provided. The former is pivotally secured
to the base at one of its ends. An arcuate arm with a slot is rigidly
attached to the fence on its non-contact side and is provided with
lock means to lock the fence in a desired angular position in relation
to the path of the saw.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A miter box for portable circular saws, comprising
a flat rigid base having a longitudinal edge; a first guide rail
rigidly secured to said base and spaced upwardly therefrom by upraising
means adjacent said longitudinal edge; a second guide rail extending
in parallel spaced-apart relationship to said first guide rail; both
said first and said second guide rails being provided with a mutually-
facing shoulder whereby a portable circular saw may be guided
thereon with the blade touching said base; further comprising a
fence pivotally secured at one of its ends to said base; and positive
alignment means to position and lock said fence in a desired angular
position.
2. A miter box as claimed in claim 1, wherein said
upraising means consists of a block rigidly secured to said base on
each corner of said longitudinal edge; said first guide rail being
rigidly secured to said blocks.
3. A miter box as claimed in claim 2, further including
lateral adjustment means for said second guide rails.
4. A miter box as claimed in claim 3, wherein said
lateral adjustment means consists of a pair of support members, one
on each lateral side of said base; a downwardly-extending flange rigidly
secured to each end of said second guide rail; said flange having a lower
portion formed with a laterally-extending slot; a threaded stud rigidly
secured to each said support member and projecting outwardly through its
associated slot; a nut to positively lock each said flange in a desired
position.
5. A miter box as claimed in claim 1, wherein said positive
alignment means consists of an arcuate arm rigidly secured to the non-
contact side of said fence; said arm being provided with a guide slot
extending throughout its length; an upwardly-extending threaded peg
rigidly secured to said base and adapted to engage said guide slot; and

a lock nut screwable on said threaded peg to lock said arcuate
arm in a desired angular position.

Description

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FIELD OF THE INVENTION
~ The present invention relates to mitsr boxes, more partic-
ularly to an improved miter bax adapted to provide guide means for a
portable circular ssw.
SACKGRpUND OF THE INvENTION
Various miter deuices havb been proposed in the prior art.
For example, Canadian Patent 613,437 diecloses a guide means tor saws
which is to be attached to a work bench. However, its construction is
relatiuely complicated, having recourse to a cast-metal frame, a vertical
pivot shaft and bearings, to mention only a ~ew of its elements. Another
patent, U.S. 3~842,700, teaches ths use Or an upper and lower plate to
sandwich the board or plank to be cut. While such a design may be ad-
vantageous for certain shapes of wood, it is certainly not essential
for the accurate sawing of wood.
Furthermore, as any amateur or professional carpenter
knows, a board which is not supported on both sides of a kerf has a
tendency to spl$nter at right angles to the ker~, especially on the
bottom sur~ace o~ the board.
O~JECTS_OF THE INVENTION
Accordingly, it i8 a ~irst object o~ the present ~nvention
- to provi~e a miter box which is very simple in design and which permits
a worker to make an accUrato cut at any Or a variety ot anglea-
It is an equally important object Or the pre~ent lnvention
to provide a miter box which supports a board or piece of wood on both
sides of the k0r~ to e~fectively prevent splintering. t
SUM~ARY Of THE IN~ENTION
The abova and other ob~ects and advantages of the present
inuention are realized according to a preferred embodiment compriaing
a flat ba~e made Or suitable rigid material. ûne o~ the longitudinal
edges o~ thi base ie provided with a first guide rail, the latter
being spaced a certàin distance above the base to provide room for a
piece of wood or board to be ~awed to pass thereunder. Upraising
means are provided at both opposite ends of this ~irst guide rail to
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maintain the latter in ri~id raised position.
A second guide rail traverses the central portion of
the base in parallel spaced-apart relationship to the first guide rail.
The second rail is also spaced above the base. Means are provided at
both its opposite ends to move the second rail laterally, either towards
or away from the first rail, but always in parallel relationship. The
guide of a portable circular power saw slides on the two rails. Thus, the
means dcscribed above constitute an adjustment means to accommodate
the varying guide widths of circular saws of different makes.
lG A fence is pivotally secured at one of its ends to the base
and is adapted to pivot through an arc of at least 60 degrees to properly
align a board to be cut at a desired angle. The non-contact side of
the fence is provided with àn~arcuate arm. This arm is in turn provided
with lock means for securing the fence at a desired angle to the base.
Th¢ above will be more clearly understood by having referral
to the preferred embodiment of the invention, illustrated by way of the
accompanying drawings, in which:
ORIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspectiue view of the disclosed miter box,
also showing in dashed outline a board in position to be sawed and a
portable circular saw;
Figure 2 is a top plan view of the miter box also showing
in dashed outline a board, and one limit position of the fence; and
Figure 3 is a lateral elevation of the miter box, also
showing a portable cirrular saw in daghed outline.
Like numerals refer to like elements throughout the
drawings.
DETAILED DESCRIPTION OF THE PREFERRED EM~ODIMENT
The miter box 1 of the present invention includes a flat,
3n rigid and rectangular base 2 having a front longitudinal edge 3. A
block 4 is rigidly sscured to each of the two corners of the edge 3.
A first guide rail 5 is rigidly secured to the blocks 4 by
screws 6, or otherwise,and extends longitudinally, spaced above base 2.
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A second guide rail 7 is provided~ extending in parallel
spaced-apart relatiDnship to first rail 5 over~the central portion o~
base 2. This second rail 7 is movably secured to a pair of support
members B. One of the latter is located on each lateral side of ba~e 2.
Lateral adjustment means ~ar rail 7 are included~ con-
sisting of a downwardly-extending ~lange ~ rigidly secured to each end
of rail 7. The lower portion of flanges 9 are each ~ormed with a laterally-
extending slot 9'. A threaded stud 10 i8 rigidly secured to each ~upport
member O and projects outwardly through its associated glot 9~.
Ooth first and second guide rails 5 and 7 are provided
with mutually-facing shoulders 12 adapted to positively guids the flqt
guide 13' of a portable circular saw 13~ as shown in Figure 1. It will
be readily appreciated that the lateral adjustment means of second rail 7
is to accommodate variously-sized power saw-guide plates 13~.
Alignment means are also provided to properly align a board~
or plank 14. The means consists of a fence 15 piuotally secured to the base
2 at 20 and adapted to swing through an arc of at leafit 60 degree~, as
indicated by the arrow in Figure 2. The non-contact side of rence 15 has an
arcuate arm 16, which i8 provided with a guide slot 16~ ;
extending throughout its l~ngth. An upwardly-extending threaded peg
17 is ~ecured to base 2 and adapted to engage s~ot 16~. Another w~ng nut
1~ is provided to lock arm 16 and, hance~ fence 15 at a chosen angle.
The simple use of the miter box 1 is readily apparents
firt the operator selects the proper distance between rails 5 and 7 by
adjusting the position of rail 7. A circular saw 13 is th7n placed on
the rails 5 and 7. Once fence 15 is locked at a specific angle, a board 14
is ~1id into position on base 2 and under rails 5 and 7. For the cutting,
saw 13 is held with one hand and board 14 with the other hand. It will
be appreciated that saw 13 may be moved in either longitudinal direction,
as suggested by shallow grooves 19 made in base 2 by circular saw 20~ it
being understood that t`he height of rails 5 and 7 above base 2 i8 such
that saw 20 makes said grooves 19.
It is to be noted that a board 14 is supported on both sides

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of thf` saw CUt to effectively eliminat~: splintering or chipping of the
wood adjacent tl)e cut. It is also easy to use the ~roove 19 receiving
saw 2û as a reference line for determining the line of cut in board 14.
~ 'hile the preferred embodiment has been specifically des-
cribed, it is to be understood that minor modifications may be made
without departinlJ from the spirit or scope of the invention.
.