Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR MANUFACTURING
HIGH-VISIBILITY MEASUREMENT TOOL
FIELD OF THE INVENTION
This invention generally relates to hand tools. More specifically, this
invention relates to a method of manufacturing measuring and marking tools
such as
rafter squares and the like.
BACKGROUND OF THE INVENTION
Carpenters frequently use framing squares, also known as rafter squares, of
different types as a means of working more efficiently and accurately. To
insure
proper perpendicularity and angularity for correct alignment of adjacent
members,
rafter squares, levels and gages are commonly employed. A metal rafter square
is
widely used in carpentry. The typical rafter square has a shape of a right
triangle with
a main portion and a heel portion perpendicular to the main portion. The main
portion
and the heel form a T-shaped cross-section. The heel portion extends along one
of the
right-angle-adjacent sides of the main portion. The main portion has various
indicia
such as periodic markings to indicate incremental lengths or angles with
respect to a
pivot point at the right angle. Some rafter squares may also include
information
regarding most-common conversions.
It is important that the measuring and marking indicia be accurate and easy to
read. Some prior rafter squares are made by stamping the markings on the main-
portion surface. The stamping process makes grooves in the main-portion
surface by
displacement of metal at the surface of the main portion. Such metal
displacement
may result in slight deviations in the markings. Of course, any even slight
deviation
may translate in measurement inaccuracies resulting in errors on the
construction site.
Clearly, high accuracy of the measurement markings is highly desirable.
Work on a typical construction site is performed under various lighting
conditions which may vary from bright sunlight to electric illumination. Many
prior
rafter squares include only a single color such that with insufficient or
excessive
lighting such markings blend with the rest of the main-portion surface and are
not
easily readable. Alternatively, in some other prior rafter squares, the
markings are
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painted in a color contrasting the color of the main-portion surface. However,
after
some use, such painted-on color tends to rub off even if the paint has been
applied
within the grooves. This results in the same single-color effect just
described. It is,
therefore, desirable to have a rafter square which is easy to use and see
under various
lighting conditions and for extended periods of time.
The heel of the rafter square is most often used to reference the square along
an edge of a framing wooden workpiece. Often, however, some wooden boards do
not have a sufficiently sharp edge for such reference. In such cases, the heel
of the
square slips off the edge and makes it very hard to retain the rafter square
in a fixed
position for making necessary measurements and marking on the wooden board. It
would be advantageous to have a rafter square which accommodates various
shapes of
wooden-board edges and allows to retain the square in a fixed position.
OBJECTS OF THE INVENTION
It is an object of the invention to provide an improved method for
manufacturing a measuring tool such as a rafter square overcoming some of the
problems and shortcomings of the prior art, including those referred to above.
Another object of the invention is to provide an improved method for
manufacturing a rafter square with high-accuracy marking indicia.
Another object of the invention is to provide a method of manufacturing a
high-visibility and easy-to-use rafter square which maintains such
characteristics for
an extended period of time.
Still another object of the invention is to provide an improved rafter square
which accommodates various shapes of wooden-board edges and allows to retain
the
tool in a fixed position for performing measurements and markings.
How these and other objects are accomplished will become apparent from the
following descriptions and the drawings.
SUMMARY OF THE INVENTION
The present invention relates to a method for manufacture of a substantially
flat rigid measurement tool of the type formed of a substantially non-ferrous
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lightweight anodized metal plate with measurement markings thereon. In the
inventive method, the metal plate is anodized to create a dark anodized layer.
It is
preferred that the dark anodized layer results in a dark preferably matt
finish of the
metal-plate surface. While the matt finish is preferred to reduce the surface
glare, a
glossy finish may also be made if so desired. The flat rigid measurement tool
such as
a rafter square is formed from such anodized metal plate. Non-removable
substantially white measurement markings are created by oxidizing selected
mark-
areas of the dark anodized surface to a depth below the anodized layer.
In highly preferred embodiments, the creating step is by application of a
laser
energy. The metal plate preferably contains aluminum. The non-removable
substantially white markings are formed by oxidized aluminum with the
substantially
white color resulting from formation of aluminum oxide. The application of
laser
energy also preferably forms grooves in the surface of the metal plate. The
depth of
the grooves is selected by programming a controller which contains
programmable
information regarding the laser application. Because the grooves and the white-
color
markings are formed by application of the laser energy, such process
substantially
eliminates any displacement of the metal at the plate surface. This, along
with the
programmable laser controller, results in highly accurate measurement
markings.
Furthermore, in the absence of any color coating, the white markings are
substantially
permanent due to the change in a chemical state of the metal plate surface.
The white
markings are highly visible on dark anodized layer. The white-on-dark contrast
of the
markings is maintained even after an extended use with repetitive rubbing.
In preferred embodiments, the metal plate is a substantially rectangular
extruded aluminum segment including a main portion and two heel portions each
extending along one of the parallel sides of the main portion and orthogonal
thereto.
It is preferred that the step of creating the measurement markings is
performed upon
such rectangular segment. The forming step further includes the step of
dividing the
substantially rectangular extruded aluminum segment into two triangular
components
each including one of the heel portions. The inventive method preferably
includes
further steps of forming and finishing the measuring tool. Such steps are
disclosed in
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commonly-owned United States Patent No. 5,901,445 (Woods et al.), the entire
contents of which are incorporated herein by reference.
It is further preferred that the heel portion of each triangular component has
a
width which is greater than 0.875 inch (2.2cm), preferably about 1.125 inch
(2.9cm).
Such enlarged heel dimension allows improved holding of the tool on boards
which in
turn further improves accuracy of the measurements and markings of the board.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a front perspective view of a rafter square made according to a
method of the present invention.
FIGURE 2 is a side perspective view from below of the rafter square of
FIGURE 1.
FIGURE 3 is a fragmentary front view of the rafter square of FIGURE 1.
FIGURE 4 is a front plan elevation showing product positions and
configurations as they occur during the forming step.
FIGURE 5 is a front plan elevation of two formed rafter squares.
FIGURE 6 is a cross-sectional view of an initial extruded metal plate.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention relates to a method for manufacture of a substantially
flat rigid measurement tool such as rafter square 10 of the type formed of a
substantially non-ferrous lightweight anodized metal plate 11 with measurement
markings 12 thereon. FIGURES 1-3 illustrate metal plate 11 anodized to create
a dark
anodized layer 13. Rafter square 10 shown in FIGURES 1-3 has dark anodized
layer
13 which results in a dark preferably matt finish of a surface 14 of metal-
plate 11. As
seen in the FIGURES, measurement markings 12 are non-removable substantially
white markings. Markings 12 are created by oxidizing selected mark-areas 15 of
dark
anodized surface 14 to a depth below anodized layer 13.
In highly preferred embodiments, markings 12 are created by application of
laser energy. Metal plate 11 shown in the FIGURES 1-3 contains aluminum. Non-
removable substantially white markings 12 are formed by oxidized aluminum with
the
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substantially white color resulting from formation of aluminum oxide which has
the
substantially white color. The application of laser energy also forms grooves
16 in
surface 14 of metal plate 11. The depth of grooves 16 is selected by
programming a
controller which contains programmable information regarding the laser
application.
As further seen in FIGURES 1-3, white markings 12 are highly visible on dark
anodized layer 13.
FIGURES 4-6 show that initially metal plate 11 is a substantially rectangular
extruded aluminum segment 20 including a main portion 21 and two heel portions
22
each extending along one of the parallel sides 23 of main portion 21. FIGURE 6
best
shows that the heel portions are orthogonal to main portion 21. FIGURE 4
illustrates
that measurement markings 12 are created upon rectangular segment 20. FIGURE 5
shows that the forming step further includes the step of dividing rectangular
extruded
aluminum segment 20 into two triangular components 24 each including one of
heel
portions 22.
FIGURE 4 depicts the different positions and configurations of segment 20 as
it moves from a first position 31 and are successively transformed into
intermediate
products 32, 33 and 34. A first hole-punching tool forms holes 55a-55d in
second
intermediate product 32. A second hole-punching tools forms holes 73a-73c
comprising the second set of holes in third intermediate product 33. A laser
device
forms measurement markings 12 in forth intermediate product 34. As seen in
FIGURE 4, hole 73b extends along a hole axis 110.
FIGURE 5 shows that forth intermediate product 34 is divided into two
semifinished components 107, 109 by moving a cutting tool, e.g., a milling
tool, along
hole 73b and, particularly, along axis 110. To divide a product 34 into two
semi-
finished components 24, 24, the length of the tool-receiving hole 73b is
extended by
milling away material at the hole ends until the hole "breaks out." Components
24 are
then finish-machined, thereby making two rafter squares 10 from each third
intermediate product 34.
FIGURE 2 further illustrates that heel portion 22 of each rafter square 10 has
an enlarged width 25 which is greater than 0.875 inch (2.2cm), preferably
about 1.125
inch (2.9cm). Such enlarged heel dimension allows improved holding of the tool
on
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boards which in turn further improves accuracy of the measurements and
markings of
the board.
While the principles of the invention have been shown and described in
connection with specific embodiments, it is to be understood that such
embodiments
are by way of example and are not limiting.
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