Referring now to the drawings, the invention comprises three rigid
elongated members of flat stock 7, 8 and 9 made of light weight material such as
aluminum, fiberglass, plastic, composite material, forming a lay out tool 50. The
members or legs 7, 8 and 9 are permanently fastened together at pivots 10a and 10b
in such a manner which allows them to be folded with all three members 7, 8 and
9 parallel to each other as shown in FIG. 1. The long edges 21, 22 and 23 are aligned
in a stacked formation, forming the profile of a single member in a top view. This
facilitates carrying and storage of the tool 50.
When folded, the tool 50 of the invention comprises three members
7, 8 and 9 stacked together with the thin edges 21, 22 and 23 of the rectangular
profiles aligned. In the folded position, the tool 50 will be held closed by means
of tension generated by the locking mechanism 4 which includes pin 11 and spring
16 with the spring loaded push button head 13 and the enlarged washer 15 affixed
to the other end of the pin or rivet 11. The tool 50 is thus kept in this position
and prevented from falling open on its own. Approximately 41370 Pascals (six pounds)
of pressure is required to disengage the lock and compress the spring 16. The intermediate
pin portion 11 of the locking mechanism 4 engages the notch 30 in the leg 9 to limit
the movement of leg 7 during folding.
In the open position shown in FIG. 2, the tool 50 will form a right
angle at the intersection of two of the members legs 7 and 8, and the other two
ends will be joined by a diagonal leg 9. In the preferred embodiment, the dimensions
of the legs will be 0.90 metres (three feet-leg) 7, 1.20 metres (four feet-leg)
8 and 1.50 metres (five feet-leg) 9.
The tool 50 creates and guarantees a perfect right angle by design,
employing the mathematic ratio of a 3-4-5 triangle. By design, the tool 50 will
retain its accuracy due to the fact that each of the three members 7, 8 and 9 are
continuously attached to one another. This maintains the integrity of the tool 50.
Two of the attachment points are precisely located rivet pivot points 10a and 10b.
The third point is a pin or rivet 11 with a push button head 13 at one end and an
enlarged washer 15 affixed to the other end engaging the surface of leg 7 which
rides in a skewed slot 12. The pin 11, as thus described functions as a spring loaded
positive position lock 4 keeping the tool 50 in the open position. Pressure on the
push button 13 releases the spring lock 4 enabling the tool 50 to close to its folded
or closed position shown in FIG. 1. Friction/tension is maintained constantly by
spring 16 to provide a controlled motion of the members 7, 8 and 9 to prevent them
from free falling.
The pin 11 which rides in the slot 12 is a two piece internal rivet
with a push button head 13 at one end and a washer 15 affixed to the other end.
The washer 15 has downwardly extending walls 26 with a central recess 27 within
which the cylindrical walls 28 of the push-button rivet 29 are mounted. The washer
head 16 includes an enlarged circular top 40 joined to an intermediate portion 31
of lesser diameter which engages the semi-circular aperture 50. The member 7 includes
a notch 16 which the pin 11 engages preventing the tool 50 from over closing or
opening in the wrong direction. The slot 12 in the member 7 is skewed at an angle
relative to the edges of the member 7. At the end of the slot 12, the spring 16
pulls the post or pin 11 into a semicircular hole thereby creating a positive lock
such as shown in FIG. 3b. The pin 11 is shown in an open position in FIG. 3a.
As a further advantage, the hole 5 maintains the tool 50 in a proper
locked position even if the forward portion of the hole 5 becomes distorted due
to repeated usage.
In the preferred embodiment the members 7, 8 and 9 are of elongated
rectangular bar stock approximately 0.3 cm (1/8 inch) thick by 5 cm (2 inches) wide.
As mentioned often the legs 7, 8 and 9 are 0.9, 1.2 and 1.5 metres) 3,4, and 5 feet)
long respectively which creates a right angle in the open position in order to layout
It is within the scope of the invention to make an assortment of sizes
and models of this tool 50, all of which retain the ratio of 3-4-5 triangle. It
is also possible to use the teachings of this invention with an isosceles triangle
which has two 45° angles and a 90° angle.
While the invention has been explained by a detailed description of
certain specific embodiments, it is understood that various modifications and substitutions
can be made in any of them within the scope of the appended claims.
BACKGROUND OF THE INVENTION
The proposed invention referred to herein as A SQUARE™,
was conceived during many years of applying the theory of a 3-4-5 triangle during
the practice of laying out perpendicular lines in the construction industry. Creating
a perpendicular line, which is any substantial length (approximately 1.20 metres
(4') or greater) requires greater accuracy than a framing square can provide due
to its size. It is this need for accuracy that dictates the use of a 3-4-5 triangle
using the present invention.
Typical application of the 3-4-5 triangle, prior to this invention,
comprised using two tape measures simultaneously, which required two people to perform
the operation with any efficiency.A SQUARE™ is a tool which creates
3-4-5 rigid triangle. Advantageously, the tool folds to a compact state with the
sides of the triangle aligned to allow it to be portable and storable. The invention
has a wide range of uses in the construction industry for many types of lay out,
i.e., framing lay out, masonry lay out, concrete form work, finish carpentry, cabinet
installation, construction supervision, ceramic tile layout, VCT tile lay out. Furthermore,
the design of A SQUARE™ gives it the ability to function as a proficient
sheet rock square by resting the 0.9 metres (three foot) leg on the ground rather
than the traditional sheet rock square which hangs from the board. The invention
may also be produced in a variety of sizes and configurations for example, an isosceles
Among the prior art patents of general interest are U.S. patents 124,222;
778,659; 1,394,088; 2,667,697; 3,345,750 and 4,955,141. The prior art patents are
not directly in point and fail to provide an anticipation of the features which
have made this invention a great success.
It is known from US 5,384,967 to provide a collapsible rafter square
which is especially adapted for the marking of angular dimensions on, or the transfer
of angular dimensions from, rafters or other building materials.
The pre-characterising features of claim 1 are known from US 5,414,938.
SUMMARY OF THE INVENTION
This invention relates to layout tools providing a right angle for
laying out perpendicular lines of any substantial length. The invention comprises
three legs or members, all of which are permanently attached at pivot points. Two
of the three points are precisely located pivot points. The third point is a precisely
located resilient locking stud or rivet which slides in a skewed slot and permits
the adjoining two members to slide into a parallel plane to one another in a compact
folded position when not in use and then into a locked open position creating a
perfect 3-4-5 triangle for layout purposes when in use. Critical to the design is
the fact that the manner in which the members are connected and aligned guarantees
a perfect and not distorted 3-4-5 triangle. This is crucial to maintain the accuracy
of the tool.
Accordingly, an object of this invention is to provide a new and improved
layout tool which provides a right angle.
A preferred object of this invention is to provide a new and improved
layout tool which includes a 3-4-5 triangle to provide an accurate 90° angle for
A further preferred object of this invention is to provide a new and
improved layout tool involving a relatively large 3-4-5 triangle which readily slides
into a compact form with the legs of the triangle in a substantially parallel plane.
Another object of this invention is to provide a triangular right
angle layout tool for laying out perpendicular lines wherein the legs are pivotally
mounted to one another at their ends and one end includes a spring-loaded rivet
which slides in a skewed slot in an adjacent leg to collapse the triangle into linearly
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and advantages of this invention may be
more clearly seen when viewed in conjunction with the accompanying drawings wherein:
- FIG. 1 is an elevation side-view with the invention in a closed position depicting
the stacking arrangement of the members or triangle legs and the pivot point mountings;
- FIG. 2 is a top plan view of the invention in an unlocked position depicting
the overall footprint of the layout tool in an unfolded triangular arrangement;
- FIG. 3a is an enlarged cross-sectional view of the rivet locking mechanism in
an open position and FIG. 3b shows the rivet mechanism in a locked position; and,
- FIG. 4a shows the washer portion of the rivet and FIG. 4b shows the internal
portion of the rivet with the push button head.