Improvements in T-squares and Drawing-board Attachments.
Year: 1892

page_text: Date of Application, 7th July, 1892-Accepted, 13th Aug., 1892
COMPLETE SPECIFICATION.
Improvements in T-squares and Drawing-board Attachments.
I, ARTHUR THOMAS PAGE, of Minneapolis, in the County of Hennepin, and
State of Minnesota, United States of America, Stationer do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
This invention relates to improvements in, T-squares and guides therefor;, and
the objects I have in view are to provide an improved T-square which can be
readily and easily adjusted to any desired position on the drawing-board with
which it is used and the blade of which can quickly be adjusted to the desired
angle with the head or can be removed and used as a ruling-edge independently of
the head; also, to improve the construction of the square in several particulars to
produce a more convenient and durable instrument.
In the accompanying drawings, forming a part of this Specification,
Figure 1 is a perspective view of a drawing-board with my T-square thereon.
Figure 2 is a top view of the plate that holds the sliding guide-bar.
Fig. 3 is a top view of the sliding guide bar.
Fig. 4 is a view of the counter-balance for the sliding guide-bar.
Fig. 5 is an end elevation of the guide-bar.
Fig. 6 is a detail section of a part of the drawing-board, grooved plate, and
sliding bar.
Fig. 7 is a detail of a portion of the lower edge of the. drawing-board, showing
the buttons for holding the drawing-board or. T-square.
Figs. 8, and 9 are details of portions. of the head of the T-square, showing the
means for clamping it to the guide-bar.
Figs. 10, 11, 12, and 13 are details of portions of a T-square, head and blade, the
head and blade being made of wood.
I
Figs. 14, 15, and 16 are similar details of the rubber. head and blade.
Fig. 17 is a view of the washer.
Figs. 18, 20, and 21 are views of the. T-square blade.
Fig. 19 is a plan of the square, showing the blade.connected to one, side of the
head and showing the brace, connected to the head and blade.
"
Fig. 22 is a detail of a portion of the blade, showing a slot in the end in place of
a perforation.
Fig. 23 is a detail of the edge of the board, showing the second set of buttons
thereon.
In the drawings, 2 represents a drawing-board, which, may be, of any ordinary
form or construction. My improved T-square is, shown in connection with this
board, with which it is adapted for use. The blade 3 of the, square is swiveled to
the head 5, and may be turned into, any desired angle across, the board.
In order that the square may be brought close to either edge of the board or
even beyond the edge and still be provided with a firm bearing for, the head, I
provide a sliding guide-bar 7, that may be drawn out beyond either edge of the
board, as in Fig. 1. The guide-bar 7 is arranged in a grooved bar 9, that is
secured across the end of the board 2. This bar may be secured to the board, by
any suitable means. I prefer to provide it with a plate, or flange that projects
under the board and has keyhole-slots 11, by which it is detachably, secured upon
screws 13, that are inserted in the under side of the board. This grooved bar, may
be applied to either edge of the board, or similar bars may be applied to two or
more edges. The bar 7 fits into the groove in the plate or bar 9, and slides freely
therein. Set-screws 15 are tapped through the wall of the groove and are adapted
to bear against the bar 7. The har 7 may be removed and used as a straight-edge,
Price 81

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if desired, and the square may be used on the board without the bar 7, as shown in
Fig. 8. The upper edge of the bar 7 is preferably cut away on the inside and
made thin for a purpose hereinafter set forth, and this upper edge, when the bar is
in place, is flush with the surface of the board. The straight-edge of the head fits
against the outer surface of the bar 7- when the square is in place, and as the square
is moved over the board the head slides along the edge of, the bar. When it is
desired to use the square at the edge of the board or to bring the head beyond this
edge, as shown in Fig. 1 the bar 7 is drawn out beyond the edge of the- board, and
forms a guide and support for the square.
As the drawing-board is often used on an incline, I provide means for counter-
balancing the sliding bar 7, so that when the set-screws are loosened it will be held
in equilibrium in the groove and may be easily moved in either direction therein.
A cord 19 is attached to the end of the bar 7 and passes over a pulley 21 and has
its end secured to the bar 9. A small weight 23 is placed on the cord, as shown in
Fig. 1.
The head of the T-square may be of ordinary form and size. It has preferably
a friction-washer 27, secured to its upper surface in position to come between the
head and the under surface of the blade. A series of radial grooves may be cut in
the head to form a protractor, by which the blade may be set at any desired angle,
(see Fig. 14) or I may provide graduations upon the edge of the metallic washer
and provide a spring 29 upon the blade that will bear against the edge of the
washer and spring into a notch therein when the blade is at right angles to the
head. This washer is preferably provided with a circular rib on its under surface
that fits into the circular groove in the top of the blade. A plate 28¹ connects the
washer with the head and prevents its turning with the blade.
It is quite often desirable to use several sizes of blades with a single T-square
head. therefore provide the head of the square with a series of fine parallel
lines 29 close together and at right angles to its straight-edge. A blade of any
size may be used on the head and the edge will coincide with one of the marks on
the head.
I prefer to provide for each head a series of blades of various sizes and materials
and form in each one a swivel-hole that is in the same position relatively to the end
of the blade. In Fig. 20 I have shown the blade provided with a strengthening-
bar 33 secured to it. This bar serves to strengthen the blade and forms a handle
by which the blade may be grasped when it is desired to raise it from the board.
It often occurs that one edge of the blade will become dented or nicked after the
square has been used for some time. It has been customary in such cases to turn
the blade over, so as to bring its other edge into use. This, however, cannot be
done with the blade having the bar on its upper side and it is never desirable to do
this as the upper surface usually becomes soiled after the square has been used for
a time, and when the blade is turned over it soils the paper. To obviate this
objection, I make the blades reversible by providing them with a swivel-hole 32 at
each end. When one edge of the blade has become uneven, I remove the blade
from the head, reverse it, and swivel the other end to the head.
The means that I use for swiveling the blade upon the head is shown particularly
in Figs. 10, 11, 12, and 13. A sleeve 41, having a head upon one end, is passed
through the head and blade and into a washer 43, placed on the blade. A screw 45
is passed through the sleeve, and a thumb-nut 47 is provided for the threaded end of
the screw. A small screw 49 is set through the head of the sleeve 41 and into the
head of the square. By this means the screw 45 is kept from turning and the
sleeve is held in the head.
It is sometimes desirable to clamp the square to the bar 7, as when a triangle is
being used with the square for section-lining. For this purpose I provide the head
of the blade with a clamp consisting of a slide 71, which is held in place by a
strap 73, that is secured to the head of the blade. The slide has a downwardly-
projecting lip 75, that is adapted to engage with the edge of the bar 7; and an
upwardly-extended opposite end- provided with a set screw 77; that bears on the

page_text: strap 73. This screw may have a rubber spring washer, if preferred.
By turning
up this screw and drawing the lip 75 against the bar the square may be held in any
desired position. A notch in the edge of the head receives the lip 75 when the
clamp is not in use. (See Fig. 8.) A rubber friction-block 72 may be inserted in
the head under the slide to keep it from moving too easily. In some instances I
prefer to provide a brace-rod extending diagonally from the blade to the head of
the square. This rod 81 is pivoted at one end to the blade, as shown in Fig. 19,
and passes through a swiveled block or post 83 on the head. A clamping screw 85:
is provided in the post, by which the rod may be clamped after the square has been
properly adjusted. The rod may be graduated and a pointer may be attached to
the post for use in setting the blade at an angle to the head. This rod firmly
braces the square and still allows the blade to be readily adjusted whenever
desirable. I may also attach a strap or tape 91 to each end of the blade and pass
them over a roller 93, mounted at the edge of the board. Light weights 95 are
attached to the ends of the tapes. When the square is used on an inclined board,
the weights counterbalance the weight of the square and keep it from sliding off
the board. The tapes may be used for marking off distances from either end of the
blade, or the blade may be detached from the head and used with the tapes alone
for parallel lining.
For the purpose of compressing the leather washer 27 after it is in place 1 prefer
to moisten this washer and then put the blade in position, then screw the nut up,
and then work the blade on its pivot back and forth, thereby solidifying the washer,
so that when it becomes dry it is hard and firm and will hold any kind of blade.
This washer may be moistened occasionally, especially when used on a rubber blade
to increase the friction.
The head of the square may be provided with holes, by which it may be hung up
when not in use.
The head may be longer at one end than at the other for
convenience in using close to the bottom edge of a drawing-board.
One edge of the blade may be made thinner and of some dark color to make a
contrast with the light edge of the blade, or vice versa, to make it easier to see the
edge when using the blade. The blade may be provided with lines 52, extending
across it and making a measure of it. To make the blades handsomer in appearance,
the blade may be colored on the top surface at the ends and the top of the head
around the blade may be gilded, as indicated at 54 in Fig. 10, to improve the
appearance and form a contact with the parallel lines thereon.
For the purpose of keeping the bar 7 at the point where it will most generally be
used the plate 9 is provided with a spring 60 at its end, which may be located on
the under side of the plate and bear against the under side of the bar. This will
create sufficient friction on the bar to keep it from moving too easily in the grooved
plate. By forming a notch 62 in the bar the spring will engage this notch and
retain the bar normally in this position; but by pressing the bar in either direction
the end of the spring will leave the notch. I may also provide a clip or lip 64 on
the head of the T-square that projects over the edge of the bar 7, and when the
square is moved up to the upper end of the bar 7 this clip will engage a notch 66
in the top of the bar, and a further movement of the square will disengage the
spring 60 from the notch in the bar and cause the bar to move along in the grooved
plate.
A plate 68 on the plate 9 projects over the bar 7 when it is in position and holds
the bar in position in the grooved plate. The upper part of the bar 7 may also be
slightly under-cut, as shown in Fig. 5, so that when the square is secured thereto
by the clamp it may be moved along on the bar without being capable of being
lifted therefrom without further releasing the clamp. The lower edge of the board
may be provided with the buttons 70, (shown in Figs. 1 and 7,) and these buttons
may be turned so as to project above the board, as indicated by dotted lines in
Fig. 7. By this means the edge of the square may be brought against these.
buttons, and the blade may then be set at right angles to the head with precision

page_text: and very quickly. For the same purpose notches 72 may be formed in the ends of
the board, having their lower edges at right angles to the end of the board. The
top of the blade may have strips of velvet 78 glued or secured thereon to hold
drawing-instruments, as shown in Fig. 21.
Instead of providing the T-square with a thumb-nut, as shown, it may have a
thumb-screw consisting of a head 74, cast upon a common screw 76, as shown in
Fig. 16. This screw would screw into a thread formed in the sleeve on the lower
washer.
By providing the plate 9 with the inclined slots 11 the plate may be attached to
various boards whether the screws 13 are located the same or not.
Instead of using the roll on the upper edge of the board I may use a roll'80) on a
rod 82, projecting from the plate 9, and the tape on the square may pass over the
roll, the other tape being omitted. I may also provide a second series of buttons 84
on the lower edge of the board, against which a second board 86 may rest, as
indicated in Fig. 23.
I prefer to use a thin calf-skin washer between the head of the square and blade,
and this washer is preferably prepared and put on as follows:
A piece of leather is first soaked in a suitable solution, so as to extract all or
nearly all of the greasy matter, and then allowed to dry. It is then cut out in the
form desired for the washer and cemented to the head with thick shellac to unite
the washer to the wood, which may be polished. Then when the washer becomes
partly set I apply water to the top side of the washer and put on the blade and
screw down the nut and then work the blade back and forth, then screw down the
nut a little tighter than at first for a moment while the leather sets a little, and
then loosen the nut a trifle and work the blade a little. The washer dries a little
and is hard, smooth, and perfect for use and will hold the blade almost immovable
when the nut is 'screwed down tight, and should the washer after a time become too
dry it can be moistened at any time to increase the friction. This is sometimes
necessary with a rubber blade to hold it very rigid with the head.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. The combination with the drawing-board, of the sliding guide-bar 7, adapted
to be drawn out beyond either edge of the board, and a support for said bar
extending across the end of the board, all substantially as described, and for the
purpose set forth.
2. The combination, with the drawing-hoard, of the grooved plate 9, secured
thereto, the sliding guide-bar arranged in said groove, and the set screws adapted
to secure said bar in said grooved plate, substantially as described, and for the
purpose set forth.
3. The combination, with the drawing-board, of the guide-bar 7, the grooved
plate 9, in which said bar 'slides, the cord 19, attached to said bar and passing over
the trolls 15 and the weight 23 on said 'cord, substantially as described.
4. The combination, with the board and the T-square having the swivel-blade, of
the sliding bar 7, adapted to be drawn out beyond either edge of the board.
5. The combination of the T-square head, with the blade, the sleeve passing
through said head and blade, the pivot screw, and the screw 49, passing through
the flange of the sleeve 'into the head of the square, with a portion of its head
fitting into a notch in the head of the pivot-screw, all substantially as described.
6. The combination, with the head and blade, of the friction washer arranged
between aid head and blade, the sleeve 41, washer 43, screw 45, and nut 47, all
substantially 'a's' described:
7. The combination, in a T-square, of the head, the blade swiveled thereto, and a
friction-washer upon the swivel-screw between said head and blade, all substantially
as described,
"

page_text: 8. The combination, with the board and the sliding guide-bar 7, of the T-square,
the slide 71, secured to said head and having the lip adapted to engage said bar,
and the clamping screw 75, for the purpose set forth.
9. The combination, with the T-square, of the sliding clamp 71, having the
downwardly-projecting lip, the strap securing said clamp to the head of the square,
and the set-screw 75, all substantially as described.
10. The combination, in a T-square, of a brace-rod pivoted to its blade, a swiveled
block or post on the head, through which said rod passes, and a clamp for securing
said rod to said post, substantially as described.
11. In a T-square, a head having a series of parallel lines at right angles to its
straight-edge and extending substantially across the head, as described, and for the
purpose set forth.
12. In a T-square, the combination of a head, a reversible blade having a swivel-
hole in each end, and a round swivel securing said blade to said end, whereby the
blade may be reversed and either end pivoted to the head.
13. In a T-square, the combination of a head, a reversible blade having a bar 33
secured to its upper surface and having a round swivel-hole in each end, for the
purpose set forth.
14. The combination, with the board having roll 93 extending along its edge, of
the T-square blade, the tapes attached to the ends of said blade and passing over
said rolls, and the weights on said tapes, for the purpose set forth.
15. The combination, with the drawing-board, of the buttons pivoted upon the
lower edge of said board, as and for the purpose set forth.
16. The combination, with the guide-bar, of the plate 9, provided with the
inclined key-hole slots 11, adapted to engage the screws on the bottom of the board,
substantially as described.
Dated this 7th day of July 1892
F. W. BARKER,
Applicant's Agent.