Improvements in Setsquares.
Year: 1891

page_text: Date of Application, 9th July, 1891-Accepted, 15th Aug., 1891-
COMPLETE SPECIFICATION.
Improvements in Setsquares.
JOSEPH HARRISON, Balgonie, Cautley Avenue, Clapham Common, London, S. W.
Instructor in Engineering, 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 a setsquare of which one edge is capable of being
adjusted to different angles, with the object of drawing lines in any required. position,
parallel, perpendicular, or symmetrically inclined to any given line or direction.
It is used in conjunction with, a straight-edge or tee square, which remains fixed or
moves parallel to itself.
Fig. 1 is a side or face elevation of the setsquare.
Fig. 2 is an edge elevation.
Fig. 3 is a section, to an enlarged scale, across G H.
Fig. 4 is a section, to an enlarged scale, across K L.
In Fig. 1, A B C D will be called the body of the setsquare, and EF the blade;
these parts are made of wood, vulcanite, metal or other suitable material. If made
of vulcanite, metal or other homogeneous material, the body may be in one piece,
without the joint at B D Fig. 1; if the material is wood, it is made with a rigid
joint B D, so that the grain of the wood may be parallel to the edges A B and B C
respectively.
One form of rigid joint is shown in Figures 1, 2 and 4; the parts A B D, BD C,
Fig. 1, are grooved along BD, to a depth PP, PP Fig. 1, and a tongue piece P,
Figs. 2 and 4 is inserted in the groove and the joint glued. If the tongue piece
is of wood, the grain must run perpendicularly to B D Fig. 1. For further
security the tongue piece may be held in position by pins S, S, S, Fig. 1.
The two edges A B, B C, of the body must be perpendicular to each other.
The blade E F, Fig. 1, which is of the same thickness as the body, is made
capable of turning about the pin M, Figs. 1 and 3, and the joint is constructed as
follows:-
N, N, Figs. 1 and 3, are two, metal plates securely fixed to the body by the
pins Q, Q, Figs 1 and 3. M, Figs. 1 and 3 is a metal pin, passing through the
plates N N and blade E F, and riveted at the ends, thus holding the plates firmly
against the blade, which is inserted between them, and forming a friction joint, the
object of which is to hold the blade in any required position relative to the body
when the setsquare is in usc. The plates N N are recessed into the body and
blade, so as to finish flush with the surface, as shown in Fig. 3, and by the dotted
lines N, N, Fig 2; this allows the setsquare to be used with either lace against the
surface of the drawing paper.
I do not restrict myself to this method of making the friction joint; thus the
plates N N might be firmly fixed to the blade, and the pin M, about which the
joint turns, be passed through the body; or two plates might be fixed to either
the body or blade and one plate to the other, and the joint made by the one plate
fitting between the two, with the pin M passing through them. The pin M might
also be made in the form of a screw and nut, instead of that of a rivet, and the
friction of the joint obtained by screwing the two together. But in whatever form
the friction joint is made, none of its details must project above the surface, so as
to prevent the setsquare being used on either face at pleasure.
The friction joint may be graduated so as to show the angle which the edge E F
of the blade makes with one or other of the edges A B, BC, of the body. The
graduations may be on either the plate N or on the blade; at T Fig. 1, the
graduations are shown on the blade.

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The setsquare is used as an ordinary one with fixed blade, for drawing lines
which are perpendicular to the edge of the tee square; and for lines inclined in any
other direction it is used thus:
To draw lines parallel to any given line or direction, set one or other edge, A B,
BC of the body, as is found convenient, against the straight-edge or tee square,
and turn the blade of the setsquare until its edge E-F is parallel to the given line
or direction; the setsquare is then moved along the straight-edge; or tee square,
and the latter along the edge of the drawing board, until E F comes into position
for drawing the required line, which will be parallel to the original one.
To draw lines perpendicular to a given line, arrange the setsquare as before, with
one edge of the body, say edge A. B, against the tee square, and adjus the blade
so that its edge E F is parallel to the given line, then, without changing the face
in contact with the drawing paper, turn the setsquare until the other edge, BC, of
the body, rests against the tee square; the edge E F is now perpendicular to its
first direction, i.e." to the given line, and the setsquare can be slid into any required
position as before described.
To draw lines symmetrically inclined to any line, the straight-edge or tee square
must first be placed with its edge parallel or perpendicular to the line or axis of
symmetry, and one or other edge of the body, say edge A B, placed against it, and
the blade EF adjusted to the required angle or direction, the actsquare is then
turned over on to its other face and the same edge A. B, applied to the tee square;.
the edge E Fis then symmetrically inclined to the axis of symmetry, and'the'
setsquare can be slid into any required position as 'before described.
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'l
claim is,
1.
1. A setsquare so constructed that the inclined edge or blade can be adjusted to
different angles, substantially and for the purposes as herein before described and
illustrated.
2. A friction joint for the adjustable blade of a setsquare, 'substantially and for.
the purposes as hereinbefore described and-illustrated.
3. A joint for the adjustable blade of a setsquare, having its details recessed
into the setsquare, and finished flush with the surface, to allow of the setsquare
being used with either face against the drawing paper, substantially and for the
purposes as hereinbefore described and illustrated.
4. The graduation of the joint for the adjustable blade of a setsquare, so as to
indicate the angle which the edge of the blade makes with either of the perpendicular
edges of the setsquare, substantially and for the purposes as hereinbefore described
and illustrated.
IN 5: The use of a setsquare with adjustable blade, for drawing lines parallel,
perpendicular, or symmetrically inclined to any given line or direction substantially
and for the purposes as hereinbefore described.
Dated this ath 1. T.1 1001