The document discusses measuring different types of fasteners. It provides examples of fastener notation that indicate the drive type, head type, material, diameter, thread, and length. It then explains how to measure the diameter, thread count/pitch, and length of fasteners. The diameter is measured on the outside of the threads in either metric notation or fractional inches. Thread density is specified in threads per inch or thread pitch in millimeters. Length is typically measured from the material to the end of the fastener. The document concludes with a short quiz to test the reader's understanding.
2. Example of fasteners notation
• Drive + Head + Fastener, Material, Diameter x Thread x Length
• Hex Bolt, SS 316, M160 x 2.0 x 80
• Phillips Flat Head Screw, Zinc, #14 – 2”
• Stud Bolt, B7, 5/8” – 11 x 100
3. Measuring Diameter
• The diameter is measured on the
outside of the threads.
• Metric size uses the notation M
for its diameter (e.g. M14)
• Inches size under 1/4” are given
as numbers (e.g. #12) instead of
inches, in order of increasing
size.
4. Thread Count & Thread Pitch
• Machine threaded fasteners
specify a thread density in
Threads Per Inch (TPI) or as a
Thread Pitch in mm (Metric).
• For a given diameter, a fastener
may be available in coarse
(standard), fine and sometimes
super fine thread.
5. Measuring Length
• Fastener length is usually
measured from where the
material is assumed to be to the
end of the fastener.
• Thus, countersunk fasteners are
measured overall and non-
countersunk fasteners are
measured from under the head.
7. Q1: What is the size of the bolt?
A) M18
B) M20
C) M25
D) 26mm
E) 3/4in
20
18
26
25
8. Q1: What is the size of the bolt?
A) M18
B) M20
C) M25
D) 26mm
E) 3/4in
20
18
26
25 Correct
Answer
Could possibly become
the correct answer if
the bolt is in inches
*Note: Always make sure the correct measuring system (Metric or Inches) beforehand.
9. Q2: What is the thread size of the bolt?
A) 2mm
B) 2.2mm
C) 22mm
D) 22 TPI
E) 22”
10. Q2: What is the thread size of the bolt?
A) 2mm
B) 2.2mm
C) 22mm
D) 22 TPI
E) 22”
Correct
Answer
Only inches bolts use the Whitworth
side of the thread gauge; which have the
“G”letter in their blades. Thus the 22 TPI
(Thread per Inch) answer.
11. Q3: What is the length of the bolt?
A) 25mm
B) 50mm
C) 80mm
D) 1in
E) 2in
80
50
25
12. Q3: What is the length of the bolt?
A) 25mm
B) 50mm
C) 80mm
D) 1in
E) 2in
80
50
25
Correct
Answer
Could possibly become
the correct answer but
uncommon to mix
metric with inch
notation together
*Note: Avoid mixing the measuring system (Metric or Inches).
