Figure 6-11. A V-slot in the base allows the tool to
be used on curved surfaces.
6.2.6 Squares
The square is used to check the accuracy of
90° (square) angles. Squares can also be used to
lay out lines at right angles to a given edge, or
parallel to another surface. Some simple machine
setups can be made quickly and easily with the
square.
There are many different types of squares
used in layout work. Two of the most common
are the hardened steel square and the double
square.
Hardened steel square
The hardened steel square, Figure 6-12, is
recommended for laying out lines when extreme
accuracy is required. It has true square or right
angles on both the inside and outside part of the
tool, and it is accurately ground for straightness
and parallelism.
Steel squares are manufactured in a number
of standard sizes up to 36″. Extreme care must be
exercised when handling the square. The blade is
mounted solidly to the beam; if the tool is
dropped, the blade can be “sprung’’ off square.
Double square
The double square is more practical than the
steel square for many jobs because the blade is
adjustable and interchangeable with other
100 Modern Metalworking
Figure 6-9.
Lines parallel to an edge can be scribed with a
hermaphrodite caliper.
Figure 6-10.
A small surface gage. It has many uses in layout
work. (L. S. Starrett Co.)
Scriber
Spindle
Base
Adjusting
screw
Figure 6-11.
A surface gage can be used to scribe lines parallel to
a surface.