Calipers
Outside and inside spring-joint calipersare the most basic and least accurate measuring tools, when they are
compared to the micrometer, vernier, dial and digital calipers. However, in
certain situations, for rough work or large tolerances, they are acceptable
measurement devices.
Outside Calipers
Outside calipers are tools used
to measure the outside surface of round or flat work. The springjoint style
caliper, Fig. 4-10, consists of two curved legs, a spring, and an adjusting
nut. Easily adjusted to size, it has no graduations and must be checked against
or set to a steel rule or a standard size gage. Figure 4-11 shows an
application where a part is measured in a lathe. With any adjustable
instrument, the machinist must develop the proper feel, which plays an
important part in determining how accurate the measurement will be.
Inside
Calipers
Inside calipers are used to
measure the diameter of holes, and the width of keyways and slots. The spring-joint
style caliper is constructed similarly to the outside caliper, with straight
legs and a very short outward curve at the end. An inside caliper is being set
to the hole size in Fig. 4-12. This inside caliper setting can be accurately
read using an outside micrometer shown in Fig. 4-13.
- Who developed the basic idea
of mass production through interchangeable parts?
-
Systems of Measurement
2. What is the common unit of
length in:
(a) the inch
system?
(b) SI?
3. Name an advantage that SI has
over the inch system.
Care of Tools
4. State two reasons why
measuring tools should be handled with care.
5. What should be done before
storing measuring tools?
6. Why should tools be stored in
separate boxes or cases?
Steel Rules
7. What is the smallest
graduation that can be clearly seen on an inch rule? On a metric rule?
8. Name two types of measuring
tools that can be used when a dimension on a print is given in decimals.
9. Name four types of steel
rules used in machine shop work.
10. What is the most common type
of rule used in machine shop work?
11. State the purpose of:
(a) hook rules
(b)
short-length rules
Measuring Lengths
12. Explain how accurate
measurements can be made if the end of the rule is worn.
13. How can a rule be used as a
straightedge?
Outside Calipers
14. Briefly explain how to set
an outside caliper to size.
15. Why is it dangerous to try
to measure work while it is revolving?
Inside Calipers
16. For what purpose are inside
calipers used?
17. Explain how an inside
caliper may be set to a size of 1¼ in. (31.75 mm).
Decimal Inch System
18. Why are decimal fractions
necessary?
19. What common decimal inch
fraction is sometimes used in machine shop work?
20. What do the figures to the
right and to the left of the decimal point represent?
21. Explain what should be done
when there are only one or two numbers to the right of the decimal point.
Copyright 2004, Industrial
Press, Inc., New York, NY