Screwed Fasteners 101
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d:\N-Design\Des5-1.pm5 Seventh Print
THEORY QUESTIONS
5.1 What is a fastener and what is meant by fastening?
5.2 What are the various applications of screwed fasteners?
5.3 Define the following terms with respect to screw threads : (a) pitch (b) pitch diameter, (c) major
diameter, (d) minor diameter, (e) lead, (f) crest, (g) root and (h) thread angle.
5.4 Distinguish between the following : (a) metric and BSW threads, (b) square and ACME threads,
(c) left hand and right hand threads and (d) pitch and lead of a thread.
5.5 What is a multi-start thread and how it differs from a single start thread?
5.6 Where are multi-start threads used and why?
5.7 What is the pitch and lead in the case of a double start thread?
5.8 What type of thread is used for the screw jack and lathe lead screw and why?
5.9 How are the following threads designated as per BIS : (a) metric thread with coarse pitch, (b)
metric thread with fine pitch, (c) square thread, (d) ACME thread and (e) worm thread.
5.10 Why hexagonal shape is preferred to square one for nuts?
5.11 Why are washers used in bolted joints?
5.12 What is a T-bolt and where is it used?
5.13 What is an eye-bolt and for what purpose is it used?
5.14 What is a stud bolt and where is it used?
5.15 Differentiate between the following:
(a) Bolt and screw, (b) machine screw and set screw, and (c) cap screw and machine screw.
5.16 What is a set screw? What is its function?
5.17 What are locking devices? Where and why are they used?
5.18 What are foundation bolts and where are they used?DRAWING EXERCISES
5.1 Sketch the internal and external ISO metric thread profile of nominal size of 25 mm and pitch of
3 mm.
5.2 Sketch the following thread profiles for a nominal diameter of 25 mm and pitch 3 mm and give
their applications:
(a) BSW thread, (b) Buttress thread (c) Square thread,
(d) ACME thread and (e) Worm thread.
5.3 Sketch a double start square thread of pitch 5 mm and nominal diameter 50 mm.
5.4 Sketch the half sectional view of a coupler, connecting two rods, each of 25 mm diameter.
5.5 Sketch the conventional representation of the following:
(a) external threads, (b) internal threads,
(c) thread in section and (d) assembled threads in section.
5.6 Give the proportions of a hexagonal nut, in terms of the nominal diameter of the bolt. Answer
with respect to the various methods followed in practice.
5.7 Draw the three views of a hexagonal headed bolt of nominal diameter 25 mm and length 100
mm; with a hexagonal nut and washer.
5.8 Sketch any two types of bolts, mentioning their applications.
5.9 Sketch the following forms of nuts, with proportions marked:
(a) flanged nut, (b) cap nut, (c) dome nut,
(d) capstan nut, (e) wing nut and (f) ring nut.
5.10 Sketch any three types of machine screws of 10 mm diameter.
5.11 Sketch any three types of cap screws of 25 mm diameter.