Note: Descriptions are shown in the official language in which they were submitted.
13023'79
BAÇKGRQUND QF THE INVENTION
This invention relates generally to instruments for use
by engineers and draftsmen to graphically draw various plans.
More specifically it relates to a T-square instrument such as
is guided along a straight edge of a drafting table for
plotting straight lines.
It is well known to all to all draftsmen that various
other drafting instruments must be used in conjunction with a
T-square in order to draw plans having lines in all different
directions. Thus various shaped triangles, protractor
trianglesl templates or other aids must be slided along a
T-square for accomplishing the task; each in~trumer.t being
selectively picked up whenever needed and thereafter removed
after each use for replacement with another, all of which
takes up a considerable total amount of time. This situation
i5 objectionable and therefore in want of an improvement.
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SUMMARY OF THE INVENTIQN
Accordingly, it is a principal object of the present
invention to provide a drafting aid which eliminates the task
of selectively picking up different drafting instruments as
needed together with a T-square, thereby saving on time, and
which additionally includes self-contained illumination for
better visibility of the drawing where needed, thus
eliminating the extra chore of shifting a nearby lamp.
Other objects are to provide an illuminated drafting aid
which is simple in design, inexpensive to manufacture, rugged
in construction, efficieDt in use and precisely accurate in
results.
Further objects of the iDveDtion will appear as the
description proceeds.
To the accomplishment of the above and related objects,
this invention may be embodied in the form illustrated in the
accompanying drawings, attention being called to the fact,
however, that the drawings are illustrative only and that
changes may be made in the specific construction illustrated
and described within the scope of the appended claims.
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BRIEF_DES~RIPT~QN OF THE DRAWING FIGURES
The figures in the drawings are briefly described as
follows:
Figure 1 is a perspective view of the invention.
Figure 2 is a top, plan view thereof.
Figure 3 is a front edge view thereof.
Figure 4 is a fragmentary perspective view of a modified
design of the invention showing the lamp being located on the
top.
Figure 5 is a right side end view of the straight edge
shown in Figure 2, and showing the slidable scale detached
therefrom.
Figure 6 is an end view of several different designs of
interfitting tongue and groove constructions that may
alternately be used in the invention.
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DET~I~ED D~RIPTION QF PREFERRED EMBODIMENT
Referring now to the drawing in greater detail, the
reference numeral 10 represents an illuminated drafting aid,
according to the present invention, wherein there is a
T-square 12 comprised of a base block 14 for sliding along a
straight edge 16 of a drafting table and a straight bar 18
attached to the base block for placement on top of a sheet of
drawing paper secured upon the drafting table. The base block
includes a keystone-shaped groove 20 along its sliding edge ~2
for engaging a correspondingly shaped tongue 24 along the
table edge 16, thereby insuring against disalignment of edges
16 and 22 and resultant inaccurate draftmanship such as
commonly occurs with a hand-held T-square.
In the present invention, the straight bar is pivotally
mounted on the base block by a pivot screw 26. A protractor
28 formed on the base-block includes a rounded edge calibrated
in degrees for alignment with a reference line 30 marked on
the bar 18. Thus the bar serves as a pivotable arm of the
protractor for drawing lines at any selected angle. A notch
32 on the base block receives a rounded end of the pivotable
bar.
The bar is notched along one longitudinal edge for
housing a scale 34 slidably held therein by means of a tongue
36 and groove 38, so that the scale may be selectively
exteDded from an end thereof, or the scale may be inverted if
made with calibrations reading in reverse directions on
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opposite sides thereof, or if one side is calibrated in inches
and the other side is calibrated in metric measurements.
An outer longitudinal edge of the scale is made to
slidably support any form of template 40, or the like, by
means of a tongue 42 and groove 44.
A depression 44 along an opposite longitudinal side edge
of the bar contains a pivotable arm 46 on a screw 48 slidable
in a slot 50 of the bar. The screw may be tightened so as to
lock the arm at any inclined angle and along any point of the
slot. The arm may be marked with any scale calibrations, as
shown at 52.
Any of the above-described, inter-engaging tongues and
grooves may be made in a design other than keystone-shaped, as
shown and suggested in Figure 6.
The invention incorporates an illumination assembly 54
which includes the base block and the ~ar components being
molded either of transparent plastic such as LUCITE~ so as to
transmit light and permit visibility therethrough. The
assembly also includes an electric lamp 56 in a socket 58
screwed into the base block and a chamber 60 in the base block
housing the lamp. Slots 62 ventilate the chamber for escape
of lamp heat. An extension cord 64 from the socket has a plug
66 on its end for conne~tion to a household electric outlet
socket. An embodiment 68 of the invention, shown in Figures 1
to 3, has the base block flat on top, whereas the embodiment
70, shown in Figure 4, has a raised position 72 on the ùase
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block containing the lamp so that it throws light rays
sidewardly over the top of the entire device.
In operative use, it is now evident that the device 10
serves the purpose of several different drafting instruments
and also includes illumination on the drafting job.
While certain novel features of this invention have been
shown and described and are pointed out in the annexed claims,
it will be understood that various omissions, substitutions
and changes in the forms and details of the device illustrated
and in its operation can be made by those skilled in the art
without departing from the spirit of the invention.
