This sample chapter is for review purposes only. Copyright © The Goodheart-Willcox Co., Inc. All rights reserved.
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Modern Metalworking
Layout Work
Figure 6-4.
A divider is designed to draw circles and arcs in
layout work.
LEARNING OBJECTIVES
After studying this chapter, you
will be able to:
• Explain the purpose of a
layout and how it is used to
prepare metal for machining.
• Identify common layout tools
and use them safely.
• Make simple layouts.
• List and observe common
safety precautions used in
layout work.
Layout is a metalworking term describing the locating and
marking of lines, circles, arcs, and points for drilling holes in
metal. These lines and reference points on the material show
the machinist where to machine.
The tools used for this work are known as layout tools.
Many common hand tools fall into this category, Figure 6-1.
The quality of the job depends on the proper and careful use of
these tools and the accuracy of the layout. This chapter will
cover the common tools and principles used in layout work.
TECHNICAL TERMS
Because of the shiny finish of metal, it is difficult to
distinguish layout lines on the surface of the material. There
are many types of coatings used to prepare the metal and make
layout lines more visible. Layout dye, Figure 6-2, is probably
the easiest to use. This blue or red-colored fluid, when applied
to metal, provides a clear contrast between the metal and the
layout lines.
combination set
divider
hermaphrodite caliper
layout dye
reference lines
scriber
square
surface gage
surface plate
trammel
Figure 6-2.
Layout dye is applied to metal to help make layout
lines stand out on the surface.
6.2.1 Scriber
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.
6.1 PREPARING METAL FOR LAYOUT
B
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.
97
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
A
Figure 6-1. Common tools used to make a simple layout.
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.
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.
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Layout Work
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Modern Metalworking
Adjusting screw
Sliding heads
Beam
Scriber points
Figure 6-7.
A trammel is used to draw large circles and arcs.
another leg pointed like a divider leg. A
hermaphrodite caliper can be used to lay out
straight or curved lines that are parallel to the
edge of the material. See Figure 6-9. It can also be
used to locate the center of a piece of irregularly
shaped stock.
Figure 6-5.
Equal spaces can be measured and laid out by
“walking’’ the divider.
6.2.4 Hermaphrodite Caliper
The hermaphrodite caliper, Figure 6-8, is
used to make lines and locate points. The tool has
one leg shaped like that of an inside caliper, and
6.2.5 Surface Gage
A surface gage is designed for many
purposes, but it is most frequently used for
layout work. It consists of a base, spindle, and
scriber. See Figure 6-10. An adjusting screw is
used for making fine adjustments. The scriber is
mounted to the spindle in such a manner that it
can be pivoted into any position.
A surface gage can be used for scribing lines
at a given height and parallel to the work surface,
Figure 6-9.
Lines parallel to an edge can be scribed with a
hermaphrodite caliper.
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
Figure 6-11.
A surface gage can be used to scribe lines parallel to
a surface.
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
Scriber
Spindle
Base
Adjusting
screw
Figure 6-6.
To set a divider to a desired size, open the legs and
align them on a steel rule as shown.
Figure 6-8.
Hermaphrodite calipers have one leg similar to that
of an inside caliper; the other leg has a replaceable
point for scribing. (L. S. Starrett Co.)
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
Figure 6-10.
A small surface gage. It has many uses in layout
work. (L. S. Starrett Co.)
The double square is more practical than the
steel square for many jobs because the blade is
adjustable and interchangeable with other
Chapter 6
Figure 6-12.
The hardened steel square has true right angles, both
inside and outside, and is designed for laying out
lines that must be highly accurate. (L. S. Starrett Co.)
blades. See Figure 6-13. This tool should not be
used where great precision is required. A double
square has a standard graduated blade, a beveled
blade, and a drill grinding blade.
The beveled blade has one angled edge for
measuring octagons, and another angle for
checking hexagons. A drill grinding blade also has
two angled edges. One end is beveled to 59° for
drill sharpening. The other end is beveled to 41°
and is used to check the cutting angles of machine
screw countersinks. Both ends are graduated for
measuring the length of the cutting lips, to ensure
the cutting tools are sharpened on center.
Layout Work
101
Figure 6-14.
A combination set is designed for many different
types of layout work.
The combination set, shown in Figure 6-14,
can be adapted to perform a wide variety of
layout operations. A complete combination set
consists of a hardened blade (a No. 4 graduated
rule), a square head, a center head, and a bevel
protractor. The blade fits all three heads.
The square head has a standard 90° edge and
a 45° edge. This makes it possible for the tool to
be used as both a standard square, Figure 6-15,
and a miter square. By projecting the graduated
blade a given distance below the edge, the tool
can also be used as a depth gage. The spirit level
built into one edge of the square head allows the
tool to be used as a simple level.
The center head has two extending edges
forming a 90° angle. With the rule properly
inserted, the center head can be used to quickly
locate the center of round stock. See Figure 6-16.
The protractor head can be rotated through
180° and is graduated accordingly. The head can
be locked to the blade with a locking nut, making
Figure 6-13.
The double square uses interchangeable blades,
making it more practical than a fixed blade square
for many jobs. It has a graduated blade, a beveled
blade, and a drill grinding blade.
Figure 6-15.
The rule and square head of the combination set can
be used to check the squareness of two machined
surfaces.
6.2.7 Combination Set
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Modern Metalworking
Figure 6-18.
A plain steel protractor can be used to measure or lay
out angles requiring only moderate precision.
Figure 6-16.
Locating the center of a section of round stock can be
accomplished by using a center head and rule.
it possible to accurately measure or lay out
angles. See Figure 6-17. The head also has a builtin spirit level, allowing the tool to be used to set
up work requiring angular cutting.
6.3 MEASURING ANGLES
There are a number of angular measuring
tools employed in layout work in addition to the
protractor head of the combination set. These
tools are discussed next. The accuracy required
by the job will determine which tool must be
used.
Plain protractor. When angles do not have to
be checked or laid out to extreme accuracy, a
plain protractor will prove satisfactory. See
Figure 6-18. The head is graduated from 0° to
180° in both directions for easy use.
Figure 6-17.
Angular measurements on layouts can be made with
the rule and protractor head of a combination set.
Protractor depth gage. This tool can be used
to check 30°, 45°, and 60° angles and measure
slot depths. See Figure 6-19.
Universal bevel. A universal bevel, Figure 6-20,
is useful for checking, laying out, and
transferring angles. Both the blade and stock
are slotted, making it possible to adjust the
blade into the desired position. A thumbscrew
locks it in place.
Vernier protractor. When a job requires
extreme angular accuracy, the machinist uses
a Vernier protractor. See Figure 6-21. This
tool enables the user to measure angles to
1/12 of a degree (5 minutes).
6.4 OTHER LAYOUT TOOLS AND
EQUIPMENT
Additional tools and equipment are
commonly used for a number of layout and
inspection tasks. These tools help produce an
accurate layout and meet the precision required
for the job.
Figure 6-19.
Protractor depth gages are used to measure angles
and depths of holes. (L. S. Starrett Co.)
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Layout Work
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Modern Metalworking
Figure 6-24.
Right angle plates are used as square references in
layout and inspection.
Figure 6-20.
The blade on a universal bevel is adjustable and can be
used to lay out and transfer angles. (L. S. Starrett Co.)
6.4.1 Precision Layout Tools
Precision layout tools are used when greater
precision is needed to produce a layout. They
commonly include Vernier-type measuring tools,
which were discussed in Chapter 5. See Figure 6-22.
These measuring and gaging tools are used to
draw lines when specifications call for locations
to be accurate to within 0.001″ (0.025 mm).
Figure 6-22.
Precision layouts can be made with Vernier height
gages and other Vernier measuring tools.
(L. S. Starrett Co.)
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.
6.4.2 Surface Plate
6.4.4 Box Parallels
A precise, flat surface is required for accurate
layout work to be accomplished. A surface plate,
Figure 6-23, is most frequently used to inspect the
flatness of layout work surfaces. Most surface
plates made today are produced from granite,
which is very stable and not affected greatly by
changes in temperature.
Surface plates are primarily designed for
layout and inspection work. They should never be
used for any task that could mar or nick the
surface.
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.
The right angle plate is used when a square
reference surface is needed. See Figure 6-24. The
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.
Figure 6-23.
Most surface plates today are made from pink or
black granite. Changes in temperature have less of an
effect on granite surface plates compared to older
semisteel surface plates. (L. S. Starrett Co.)
Figure 6-25.
Box parallels.
6.4.3 Right Angle Plate
Figure 6-21.
A Vernier protractor is employed to make precise
angular measurements. In this application, a protractor
is mounted on a height gage. (L. S. Starrett Co.)
6.4.5 V-Blocks
Figure 6-26.
V-blocks are available in a number of sizes. They
support round work for layout and inspection.
6.4.6 Straightedge
Flat surfaces can be checked with a straightedge, 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 6-27.
Straightedges are employed to lay out long, straight
lines. They are commonly made from steel or granite.
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Layout Work
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Modern Metalworking
1. Cut the stock to the
approximate size.
4. Scribe in the circles
and arcs.
2. Locate and scribe
the base lines.
5. Locate and scribe the
angular lines.
3. Locate and scribe the
circle and arc centerlines.
6. Scribe in the remaining
lines.
Figure 6-28.
This drawing provides the information necessary to make a simple layout.
2. Cut the stock to size. Remove all burrs (sharp
edges remaining on the metal after cutting,
stamping, or machining).
3. Clean the work surface. Remove any oil and
grease and apply layout dye to the metal.
4. Locate and scribe the layout reference lines or
base lines. Make all of your measurements
from these lines. If the material has one true
edge, it can be used in place of a reference line.
5. Locate the center points of all circles and
arcs.
6. Use a prick punch, Figure 6-30A, to mark the
points where the centerlines intersect. The
sharp point of this punch makes it easy to
locate these points. After a mark has been
checked and found on center with the prick
punch, it is enlarged with a center punch. See
Figure 6-30B.
7. Use a divider to scribe in all circles and arcs.
8. Scribe in any necessary angular lines. Use the
proper protractor measuring tool or locate
and connect the correct points by using a rule
or straightedge.
9. Scribe in any other internal openings and lines.
10. Complete the layout with clean, sharp lines.
Any double lines or sloppy line work should
be removed by cleaning the metal with a
solvent. Apply another coat of dye and then
scribe the lines again.
6.6 SAFETY PRECAUTIONS FOR
LAYOUT WORK
Proper safety must always be practiced
when performing layout work. Layout tools are
Figure 6-29.
The sequence of steps involved in laying out the job shown in Figure 6-28.
sharp objects and require careful handling. Large
pieces of metal stock and other materials can
pose hazards and must be handled safely.
The following precautions should be
observed when laying out a job:
Never carry an open scriber, divider,
trammel, or hermaphrodite caliper in your
pocket.
Always cover all sharp tool points with a cork
when the tool is not in use. When laying out
work, place tools on the bench with the
points facing away from you.
Avoid handing a sharp tool to another
person with the pointed end sticking out.
Wear goggles when grinding the points of a
scriber.
Get help if you have to move heavy angle
plates, large V-blocks, or other large
equipment.
Remove all burrs and sharp edges from the
stock before starting the layout.
Chapter 6
Prick punch
A
Center punch
B
Figure 6-30.
A prick punch and center punch. A—The prick
punch has a more sharply angled point than a center
punch. It is used to mark the intersections of
centerlines. B—After checking for accuracy, marks
for the locations are enlarged with a center punch.
SUMMARY
Layout work plays an essential role in many
areas of metalworking. It is very important to
understand how layout and measuring tools are
used to produce a simple layout. Making an
accurate layout requires careful study of the print,
the development of a sequence of operations, and
the precise placement of lines and marks.
A properly developed layout provides the
locations necessary to machine the work. It helps
ensure the job is completed correctly and accurately.
TEST YOUR KNOWLEDGE
Please do not write in this text. Write your
answers on a separate sheet of paper.
1. Define the process known as layout.
2. Layout lines are used to _____.
(a) take the place of blueprints
(b) tell the machinist where to machine
(c) give the machinist practice in measuring
(d) None of the above.
3. Layout _____ is used on metal to make
layout lines more visible.
4. What is a scriber?
5. A _____ is used to draw circles and arcs on
metal.
(a) hermaphrodite caliper
(b) divider
(c) spindle
(d) None of the above.
Layout Work
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Modern Metalworking
6. What are the three major parts of a surface
gage?
7. What is the difference between a hardened
steel square and a double square?
8. A combination set cannot be used to _____.
(a) draw angular lines
(b) measure depths
(c) draw circles and arcs
(d) level angular surfaces
9. The _____ of the combination set can be used
to quickly locate the center of round stock.
10. A _____ is used for jobs requiring extreme
angular accuracy.
(a) protractor depth gage
(b) Vernier protractor
(c) plain protractor
(d) spirit level
11. What is a surface plate?
12. _____ are frequently used to support round
stock for layout and inspection.
(a) V-blocks
(b) Box parallels
(c) Right angle plates
(d) Trammels
13. Straightedges are made from _____ or _____
and are available in a wide range of sizes.
14. What are reference lines?
15. A(n) _____ punch is used to mark the points
where centerlines intersect on a layout. A(n)
_____ punch is used to enlarge the points
identifying the center marks.
RESEARCH AND DEVELOPMENT
1. Write a report on how surface plates are
made. Why are they made of cast iron and
granite, and not other materials?
2. Prepare several overhead transparencies
showing the proper sequence for making a
layout. Make a tape recording of your
presentation to the class.
3. Develop a display illustrating several
different types of layout dyes used on stock.
Protect your samples with clear plastic
spray to prevent the scribed lines from
rusting.
Top quality hand tools are forged to shape rather than cast. Pictured are a
few of the many types and sizes of forged pliers available to the craftworker.
How many of the pliers can you identify?