98 Modern Metalworking
All grease and oil must be removed from the
metal before the dye is applied. Otherwise, it will
not adhere properly. Other coatings, such as
chalk, can also be used on hot-rolled steel as a
layout background.
6.2 LAYOUT TOOLS
Precision-made tools are commonly used to
draw layout lines, arcs, and points on metal.
There are many different types of tools and
measuring instruments used in metalworking.
The next section of this chapter discusses some of
the most common layout tools.
6.2.1 Scriber
Accurate layout work requires fine lines to
be scribed or scratched into the metal. A scriber
is commonly used to produce these lines,
Figure 6-3. The point of this tool is made of
hardened steel; it is kept needle-sharp by
frequent honing on a fine oilstone. Many types
of scribers are available.
Always use a scriber with caution and
handle it with care. Never carry an open scriber in
your pocket. It can cause severe puncture wounds.
6.2.2 Divider
Scribers are designed to draw straight and
slightly curved lines. Circles and arcs are made
with the divider, Figure 6-4. Dividers have two
pointed legs and a stem for turning the tool. It is
essential that both legs of the tool be equal in
length and kept pointed.
Dividers are commonly used to lay out and
measure distances. See Figure 6-5. To set the tool
to the correct dimension, place one point on an
inch mark or metric division on a steel rule, and
open the divider until the other leg is set to the
right distance. See Figure 6-6.
6.2.3 Trammel
A trammel is used to draw circles and arcs
too large to be made with a divider. See Figure 6-7.
A trammel consists of two sliding heads with
scriber points mounted on a long, thin rod called
a beam. One of the heads is fitted with an
adjusting screw. Extension rods can be added to
the beam to increase the capacity of the tool.
Figure 6-2.
Layout dye is applied to metal to help make layout
lines stand out on the surface.
Figure 6-4.
A divider is designed to draw circles and arcs in
layout work.
Figure 6-3.
Scribers are used to mark layout lines on metal.
A—The long bent point of this scriber is handy for
reaching through holes. B—This pocket scriber has a
removable point that should be reversed when the
tool is not in use. The hexagon head prevents the tool
from rolling when placed on a flat surface.
A
B