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126 PREPARATION OF CAVITIES
Technical Exercises
On six cubes of plaster of Paris 2 inches square, prepare
the six forms of mortise. Study the line and point angles
in^these imaginary cavities.
Fig. 135. Fig. 136. Fig. 137.
Fig. 135.—Simple mortise on one surface.
Fig. 136.—Simple dovetail mortise on one surface. The plaster block has been
sawed in half to show the inside of the cavity, which is dovetailed on two opposite
surfaces.
Fig. 137.—Simple mortise form involving two surfaces.
Fig. 138. Fig. 139. Fig. 140.
Fig. 138.—Method of dovetailing the simple rnortise involving two surfaces,
thus making it retentive in form.
Fig. 139.—Auxiliary mortise (step form).
Fig, 140.—Compound dovetail mortise.
I
Rules for obtaining resistance form.
K Rule I.—In the shaping of all simple cavities, use the
Examples
simple mortise form, or some modification of it.
Technical Exercises
On six cubes of plaster of Paris 2 inches square, prepare
the six forms of mortise. Study the line and point angles
in^these imaginary cavities.
Fig. 135. Fig. 136. Fig. 137.
Fig. 135.—Simple mortise on one surface.
Fig. 136.—Simple dovetail mortise on one surface. The plaster block has been
sawed in half to show the inside of the cavity, which is dovetailed on two opposite
surfaces.
Fig. 137.—Simple mortise form involving two surfaces.
Fig. 138. Fig. 139. Fig. 140.
Fig. 138.—Method of dovetailing the simple rnortise involving two surfaces,
thus making it retentive in form.
Fig. 139.—Auxiliary mortise (step form).
Fig, 140.—Compound dovetail mortise.
I
Rules for obtaining resistance form.
K Rule I.—In the shaping of all simple cavities, use the
Examples
simple mortise form, or some modification of it.
