104 Modern Metalworking
plate can be placed in almost any position to
establish a perpendicular edge. The work is
commonly clamped to the face of the plate for
layout, measurement, or inspection tasks.
6.4.4 Box Parallels
Accurate surfaces parallel to the surface
plate can be obtained by using box parallels,
Figure 6-25. These tools are available in a number
of sizes. Each tool surface is precisely ground to
close tolerances for accuracy.
6.4.5 V-Blocks
V-blocks are used to support round work for
layout and inspection. See Figure 6-26. These
tools are furnished in matching pairs with
surfaces ground square to close tolerances. Ribs
are cast into the body of the block for strength
and weight reduction; they are also used as
clamping surfaces. V-blocks are available in a
number of sizes.
6.4.6 Straightedge
Flat surfaces can be checked with a straight-
edge, Figure 6-27. The tool can also be used to lay
out long, straight lines. Straightedges are
manufactured from steel or granite in a wide
range of sizes. They must be carefully handled to
prevent nicks to the reference edge.
6.5 MAKING A LAYOUT
Each layout job has its own specifications
and number of operations. Before any layout
operation can be started, the tasks and tools
required to complete the job should be carefully
considered. Once a drawing is studied closely
and the necessary operations are determined, the
metal should be prepared and marked properly.
A drawing for a typical job is shown in
Figure 6-28. The following steps are used to
complete the layout:
1. Study the drawing carefully and then plan
the layout sequence, Figure 6-29.
Figure 6-26.
V-blocks are available in a number of sizes. They
support round work for layout and inspection.
Figure 6-24.
Right angle plates are used as square references in
layout and inspection.
Figure 6-25.
Box parallels.
Figure 6-27.
Straightedges are employed to lay out long, straight
lines. They are commonly made from steel or granite.