Figure 2-22.--Laying out an irregular line from a surface.
fit. In view B the divider has scribed a line from left
to right. When scribing horizontal lines, keep the legs
of the divider plumb (one above the other). When
scribing vertical lines, keep the legs level. To scribe a
line to an irregular surface, set the divider so one leg
will follow the irregular surface and the other leg will
scribe a line on the material that is being fitted to the
USING THE SURFACE PLATE
Figure 2-21.--Laying out circles.
Use the surface plate with such tools as parallels,
set on a graduation. Place one leg of the divider at the
squares, V-blocks, surface gauges, angle plates, and
center of the proposed circle. Then, lean the tool in
sine bars to make layout lines. Use angle plates
the direction it will be rotated and rotate it by rolling
the knurled handle between your thumb and index
at an angle on the surface plate. To set the angle of the
angle plate, use a protractor and rule of the
When setting trammel points, shown in view B of
combination square set or use a vernier protractor.
divider. You may need a steel tape to set the trammel
To lay out a circle with trammel points, hold one
point at the center and lean the tool in the direction
you plan to move the other point. Then, swing the
To transfer a distance measurement with trammel
points, hold one point as you would to lay out a circle.
Then, swing a small arc with the other point opened to
the desired distance.
Scribing an irregular line to a surface is a skill
used to fit a piece of stock to a curved surface, as