ENT250: MECHANICAL MANUFACTURING SKILLS

• TIME: 8.00 AM – 11.00 AM, WEDNESDAYS AND
THURSDAYS
• VENUE: ENGINEERING WORKSHOP &
TEACHING FACTORY
•
LECTURER: MR. AZIZUL MOHAMAD
•
PLVS: MR. AHMAD FAIZAL, MR. SYAYUTHI &
MR. ANUAR
• TECHNICIANS: MR. ZALIZAM, MR. RIMI
RAFEEK & MR. NIZAM
ENT250: MECHANICAL MANUFACTURING SKILLS

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METROLOGY ( 1 WEEKS)
•
CONVENTIONAL MANUFACTURING –
–
WELDING ( 2 WEEKS)
– CONV. MILLING (2 WEEKS)
–
CONV. TURNING (2 WEEKS)
•
COMPUTER-AGE MANUFACTURING
–
CNC TURNING (2 WEEKS)
–
CNC MILLING (2 WEEKS)
–
WIRE EDM (2 WEEKS)
ENT250: MECHANICAL MANUFACTURING SKILLS

•
ASSESSMENT
–
100% COURSEWORK, NO FINAL EXAM

• LAB REPORT
• TESTS AND QUIZZES
• ASSIGNMENTS
•
CASE STUDY
•
MINI PROJECT
•
TEXTBOOK
–
TECHNOLOGY OF MACHINE TOOLS, 6 TH ED.
KRAR, GILL & SMID. MCGRAW-HILL
•
SPECIAL PRICE: RM 75.00 (RRP RM130.00)
–
LECTURE NOTES AND LAB MODULES
ENT250: MECHANICAL MANUFACTURING SKILLS

ENT250: MECHANICAL MANUFACTURING SKILLS

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Egyptians used length called cubit
– Equal to length of forearm (middle finger to elbow)
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James Watt measured tolerances of steam engine with thickness of thin shilling
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International System of Units (SI) developed in 1960
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Two major systems of measurement
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Inch system in US and Canada
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Metric system for 90% of world
ENT250: MECHANICAL MANUFACTURING SKILLS

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Jan 16, 1970, Canada adopted SI for implementation throughout Canada by 1980
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Dec 8, 1975, US Senate passed Metric Bill
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Will take long time to convert
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All machine tools and measuring devices will have to be redesigned
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Long life expectancy of costly machine tools
– People resistant to change
ENT250: MECHANICAL MANUFACTURING SKILLS

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Inch Dimensions
– Zero not used before decimal point for values less than 1 inch
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Dimension expressed to same number of decimal places as its tolerance
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Metric Dimensions
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Zero used before decimal point if < 1 millimeter
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Whole number uses no decimal point nor zero
– Decimal fraction of a millimeter – last digit to right of decimal point not followed by zero
ENT250: MECHANICAL MANUFACTURING SKILLS

Following is list of some common SI quantities, names, and symbols you are likely to encounter when working in the machine shop.
Quantity length volume mass time
Name meter liter gram minute second
Symbol m
 and l g min s
ENT250: MECHANICAL MANUFACTURING SKILLS

Quantity force pressure, stress temperature area velocity (speed)
Name newton pascal degree Celsius square meter meters per minute meters per second angles degrees minutes seconds volt electric potential electric current frequency ampere hertz electric capacitance farad
Symbol
N
Pa
°C m 2
' m/min m/s
°
''
V
A
Hz
F
ENT250: MECHANICAL MANUFACTURING SKILLS

These prefixes often used with quantities: length, volume, mass, pressure, stress, area
Prefix micro milli centi deci deka hecto kilo mega
Meaning one-millionth
Multiplier Symbol
.000 001 one-thousandth .001
µ m one-hundredth one-tenth ten one hundred one thousand one million
.01
.1
10
100
1 000
1 000 000 c d da h k
M
ENT250: MECHANICAL MANUFACTURING SKILLS

ENT250: MECHANICAL MANUFACTURING SKILLS

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Unit of length is the inch
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May be divided into fractional or decimal fractions
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Fractional system based on binary system
• Common fractions: 1/2, 1/4, 1/8, 1/16, 1/32, 1/64
– Decimal-fraction system uses base 10
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Number written as product of 10 or fraction of 10
ENT250: MECHANICAL MANUFACTURING SKILLS

Value one-tenth one-hundredth one-thousandth one ten-thousandth
Fraction
1⁄10
1⁄100
1⁄1000
1⁄10,000 one hundred-thousandth 1⁄100,000 one millionth 1⁄1,000,000
Decimal
.1
.01
.001
.0001
.00001
.000001
ENT250: MECHANICAL MANUFACTURING SKILLS

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Linear dimensions expressed in multiples and submultiples of meter
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Millimeter most common
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Fractions of millimeter expressed in decimals
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Brief comparison of common inch and metric
1 yd = 36 in.
1 m = 39.37 in.
1000 m = 1 km
1 km = 0.621 mi
1 mi = 1.609 km
ENT250: MECHANICAL MANUFACTURING SKILLS

Metric Size mm cm
1 in.
25.4 2.54
1 ft 304.8 30.48
1 yd 914.4 91.44
dm
0.254
3.048
9.144
m
0.0254
0.3048
0.9144
ENT250: MECHANICAL MANUFACTURING SKILLS

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Measured with rulers or calipers
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Steel rules graduated
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Binary-fractional divisions
• 1, ½, ¼, 1/8, 1/16, 1/32, 1/64
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Decimal fractional divisions
• decimeters, centimeters, millimeters, half-millimeters
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1/64 in. or 0.50 mm. smallest used
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Precision instruments
– Micrometers and verniers used for dimensions of less than 0.50 mm
ENT250: MECHANICAL MANUFACTURING SKILLS

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Metric steel rules graduated in millimeters and half-millimeters
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Linear measurement without great accuracy
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Lengths from 15 c. to 1 m.
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Factional steel rules graduated in common binary fractions (1/8 – 1/64 in.)
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Several varieties (spring-tempered, flexible, narrow, and hook)
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Lengths range from 1 to 72 in.
ENT250: MECHANICAL MANUFACTURING SKILLS

• Fairly accurate measure with steel rules
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Butt end of rule against shoulder or step
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Steel rules become worn with constant use
– Can make measurements taken from end inaccurate
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Compensate by measuring from 1-in or 1-cm mark and subtracting 1 from measurement
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Keep edge of rule parallel to edge of work
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Rule used as straightedge to test flatness of workpieces
– Edges ground flat: place, hold to light and view
ENT250: MECHANICAL MANUFACTURING SKILLS

• Not precision tools
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Used to approximately measure outside surface of either round or flat work
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Do not use when accuracy < .015 in.needed
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Several styles
– spring joint
– firm joint
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Used to measure diameter of holes or width of keyways and slots
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Several styles
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Spring joint
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Firm Joint
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

ENT250: MECHANICAL MANUFACTURING SKILLS

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Five categories of tools based on the dimension being measured
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Outside
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Inside
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Depth
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Thread
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Height
ENT250: MECHANICAL MANUFACTURING SKILLS

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Standard inch micrometer accurate to .001 in.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Two important thread terms
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Pitch
• Distance from point on one thread to corresponding point on next thread
• Inch threads pitch expressed as 1/N(Number of threads)
• Metric threads expressed in millimeters
– Lead
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Distance screw thread advances axially in one complete revolution
ENT250: MECHANICAL MANUFACTURING SKILLS

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Zero line on thimble lined up with index line on sleeve (barrel)
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Measuring faces just touch
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Pitch is 1/40 (.025) in. since 40 threads
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One complete revolution of spindle, one line appears
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Every fourth line longer (represents .100 in.)
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Thimble has 25 equal divisions
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Represents .001 in.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Note last number showing on sleeve and multiply by .100
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Note number of small lines visible to right and multiply by .025
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Note number of divisions on thimble from zero to line that coincides with index line on sleeve and multiply by .001
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Add three products to get total reading
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Note last number showing on sleeve and multiply by .100
2 x .100
.200
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Note number of small lines visible to right and multiply by .025
3 x .025
.075
3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Note number of divisions on thimble from zero to line that coincides with index line on sleeve and multiply by .001
13 x .001
.013
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Add three products to get total reading
.200
.075
.013
.288 in.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

Added to sleeve
Scale consists of 10 divisions that run parallel to index line.
Friction thimble
Each division on vernier scale has a value of .0001 in.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Read as would a standard micrometer
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Note line on vernier scale that coincides with one on thimble
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Indicates number of ten-thousandths
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Multiple the line number times .0001
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Add to total of the other readings
ENT250: MECHANICAL MANUFACTURING SKILLS

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Similar to inch micrometer with two exceptions
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Pitch of spindle screw (0.5 mm)
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Graduations on sleeve and thimble
• Above index line on sleeve, graduations in millimeters
(from 0 to 25) with every fifth line numbered
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Below index line, each millimeter subdivided into two equal parts of 0.5 mm
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Thimble circumference in 50 equal divisions (0.01mm)
ENT250: MECHANICAL MANUFACTURING SKILLS

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Note number of last main division showing above line to left of thimble
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Multiply that number by 1 mm
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If there is half-millimeter line showing below index line, between whole millimeter and thimble, add 0.5 mm
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Multiply number of line on thimble that coincides with index line times 0.01
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Add these products
ENT250: MECHANICAL MANUFACTURING SKILLS

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In addition to graduations on standard micrometer, has five vernier divisions on barrel (each = .002 mm)
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Major division below index line
– Each = 1 mm
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Minor division above index line
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Each = .5 mm
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Fifty divisions around thimble
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Each =0.1 mm)
ENT250: MECHANICAL MANUFACTURING SKILLS

VERNIER DIVISIONS
Each division = 0.002 mm
Graduation = 0.01 mm
THIMBLE
SLEEVE
35
30
25
20
MINOR DIVISION
Graduation = 0.5 mm
MAJOR DIVISION
Graduation = 1mm
0 5 10
10 + 0 + .16 + .004 = 10.164
15
10
5
ENT250: MECHANICAL MANUFACTURING SKILLS

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Will give readings in both inch and metric
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Digital reading for one system, standard barrel and thimble reading for other
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Another type has dual scales on sleeve and thimble
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Test periodically to ensure accuracy
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Clean measuring faces before testing
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Turn thimble using friction thimble or ratchet stop until measuring faces contact each other
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Zero line on thimble coincides with center index line on sleeve = accuracy
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Can also check by measuring gage block or other known standard
ENT250: MECHANICAL MANUFACTURING SKILLS

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Clean measuring faces; inspect for damage
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Close measuring faces carefully by turning ratchet stop or friction thimble
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Insert C-spanner into hole or slot in sleeve
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Carefully turn sleeve until index line on sleeve coincides with zero line on thimble
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Recheck accuracy
ENT250: MECHANICAL MANUFACTURING SKILLS

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Direct-reading micrometer
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Additional digital readout built into frame
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Large-frame micrometer
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Made for measuring large outside diameters up to 60 in.
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Interchangeable anvils give range of 6 in.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Indicating micrometer
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Uses indicating dial and movable anvil
– Accurate to ten-thousandths of an inch
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Can be used as a comparator with gage blocks
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Mul-T-Anvil micrometer
• Used for measuring tubing and distances from a slot to an edge
Round and flat anvils
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Used as hand gage for inspecting small parts
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Accurate up to 50 millionths of an inch and displays both inch or metric sizes
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Statistical process control when added provides stand-alone inspection system
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Interface with PC
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Measures pitch diameter of threads
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Pointed spindle and double-V swivel anvil
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Shaped to contact pitch diameter of thread
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Equal to outside diameter less depth of one thread
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Limited to certain range
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Four ranges for one-inch
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8-13 TPI
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14-20 TPI
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22-30 TPI
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32-40 TPI
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Ranges stamped on micrometer frame
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Metric available also in ranges
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0-25 mm
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25-50 mm
– 50-75 mm
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75-100 mm
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Helix angle of thread can give slightly distorted reading
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First set thread micrometer to thread plug gage
ENT250: MECHANICAL MANUFACTURING SKILLS

ENT250: MECHANICAL MANUFACTURING SKILLS

Used to lock readings into place
Bar of 25-division vernier scale graduated same as micrometer
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
Manufactured with both 25- and
50-division vernier scales
ENT250: MECHANICAL MANUFACTURING SKILLS

1 x 1.000= 1.000
4 x 0.100= .400
1 x 0.050= .050
14 x 0.001= .014
1.464 in.
A 50-division inch vernier caliper reading of 1.464 in.
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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Many have both metric and inch graduations
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Parts same as inch vernier
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Main scale graduated in millimeters
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Every main division numbered, equal to 10 mm
– Fifty graduations on sliding scale with every fifth one numbered
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50 graduations occupy same space as 49 graduations on main scale (49 mm)
• 1 vernier division = 0.98 mm so difference between 1 main scale division and 1 vernier division = .02 mm
ENT250: MECHANICAL MANUFACTURING SKILLS

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Last numbered division on bar to left of vernier scale represents number of millimeters multiplied by 10
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Note how many full graduations showing between this numbered division and zero
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Multiply number by 1 mm
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Find line on vernier scale that coincides with line on bar and multiply by 0.02 mm
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Add for total reading
ENT250: MECHANICAL MANUFACTURING SKILLS

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Dial indicator, hand attached to pinion, mounted on sliding jaw
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Metric: 1 revolution of hand = 2 mm of travel
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Inch: 1 revolution = .100 or .200 in. of travel
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Depends on manufacturer
•
Most have narrow sliding blade attached to sliding jaw (and dial) used depth gage
ENT250: MECHANICAL MANUFACTURING SKILLS

• Can provide readings to resolution of
.0005 in. or 0.01 mm at touch of button
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No rack, pinion or glass scale
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Can connect to Statistical Process Control (SPC) equipment for inspection purposes
• Measurements
– Inside diameter
–
Outside diameter
– Step
– Depth
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
ENT250: MECHANICAL MANUFACTURING SKILLS

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PLEASE GO TO THE RESPECTIVE
VENUE BASED ON YOUR GROUP :
–
GROUP A => ENGINEERING WORKSHOP,
PIC: MR ANUAR & MR SYAYUTHI
–
GROUP B => TEACHING FACTORY, PIC:
MR AHMAD FAIZAL & MR. AZIZUL
•
ASSIGNMENT 1: PLEASE SEE PORTAL,
DUE 26 TH JULY 2006, 5.00 PM & MY
OFFICE IN JEJAWI
ENT250: MECHANICAL MANUFACTURING SKILLS