CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Lesson Topics
 Shop safety (p. 19)
 Shop math (p. 23)
 Introduction to blueprint reading (p. 39)
 Tolerance interpretation (p. 44)
 Measuring devices (p. 50)
Special note: Any one of these topics
could fill an entire course by itself. We
only scratch the surface of each topic.
Our intention is simply to provide
enough information about basic
machining practices so that students
can understand upcoming
presentations.
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More things to do for this lesson:
Shop math practice
Shop math quiz
Blueprint reading quiz
Tolerance interpretation review and practice
Tolerance interpretation quiz
Drawing for exercise 1
Lesson topics
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop safety
 A machine shop is a dangerous place!
 We cannot prepare you for every
dangerous situation
 You must always be alert
 Safety equipment
 Protective eyewear
 Clothing
 Hearing protection
 Safety shoes
 Helmets
 Gloves
 Respirators and facemasks
 First aid kits
 Fire extinguishers
 Cranes and hoists
 Warning signs
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Lesson topics
 Safety practices
 When in doubt, ask!
 Raw material handling
 Heavy, sharp, greasy, slippery,
dirty, sharp edges, chip residue,
awkward shape
 Finished workpiece handling
 In addition to raw material
handling:
 Hot
 Spring
 Tightening and loosening fasteners
 Getting around in the shop
 Behave in a professional manner
 No horseplay!
 Machining-center-specific safety issues
 Safety interlocks, guarding, signs,
safe operating procedures
Next topic: Shop math
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Calculator recommendations
 Keep it simple
 Watch out for trick functions
 Avoid solar powered calculators
 Big buttons-big display
 Clear entry button
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Arithmetic operations
Most CNC operator work can be done with
the four basic arithmetic operators:
Add (+): 3 + 4 = 7
Subtract (-): 7 - 4 = 3
Multiply (X or *): 2 * 9 = 18
Divide (/): 20 / 2 = 10
Entries into CNC machines are done in
decimal format (fractions are never used)
1/8 = 0.125
3/16 = 0.1875
You may be able to do some
calculations in your head
20 / 2 = ? (20 divided by 2)
2.5 + 0.5 = ?
3.0 - 0.25 = ?
5.25 + 8.75 = ?
109.75 - 3.5 = ?
But don’t hesitate to use your
calculator if you’re in doubt
125.352 - 13.837 = ?
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Arithmetic expressions
An expression is a math question to be answered…
Answer
3+4=7
Question
4+6–2=?
7–3+5=?
10 * 2 / 5 = ? (10 times 2 divided by 5)
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Priority of arithmetic operations
Consider this expression:
3
16
4 + 12 / 4 = ?
4 + 12 / 4 = ?
What answer did you come up with?
4 plus 3 is 7
16 divided by 4 is 4, right?
But wait a minute – there is
another way to do this…
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Lesson topics
Which answer is correct?
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Priority of arithmetic operations
With no other math “punctuation”…
… division has a higher priority than addition
3
4 + 12 / 4 = ?
4 plus 3 is 7
The correct answer is 7
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Priority of arithmetic operations
Order of arithmetic priorities:
Parentheses can be used to
specify operation order
1)
2)
( )
(4 + 12) / 4 = ?
This makes it clear that 4 must be
added to 12 first. Then the result (16)
is divided by 4. The answer is 4.
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Lesson topics
3)
4)
5)
6)
Anything in parentheses
Functions (like square root,
sine, cosine, tangent)
Multiplication
Division
Addition
Subtraction
3 * (4 + 2) = ?
5 + 0.5 / 2 = ?
(8 + 2) / 5 = ?
7+9/2=?
4+1/2-2=?
8 * (2 + 3) / 2 = ?
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Using a formula
A formula is an arithmetic
expression that contains variables
rpm = 3.82 * sfm / tool diameter
With this formula, consider this situation:
You need to drill a 0.5 in diameter hole
and the cutting tool manufacturer
recommends 80 surface feet per minute.
rpm = 3.82 * 80 / 0.5
 rpm represents spindle
revolutions-per-minute
What rpm will you use?
 sfm represents speed in surfacefeet-per-minute
 tool diameter represents the
diameter of the cutting tool
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Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Measurement systems
Some companies in the United
States use the Imperial system
Other companies use the Metric system
(the Metric system is used almost
exclusively in other countries)
The inch is the most basic unit of
distance in the machine shop
The millimeter is the most basic unit
of distance in the machine shop
How big is an inch?
How big is a millimeter?
A deck of playing cards is
about ½ an inch
One inch = 25.4 millimeters
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Lesson topics
The thickness of a quarterdollar is about one millimeter
One millimeter = 0.0397 inches
(about one-twenty-fifth of an inch)
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Measurement systems
To convert millimeters to inches:
To convert inches to millimeters:
inches = millimeters / 25.4
millimeters = inches * 25.4
How many inches is 350 millimeters?
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Lesson topics
How many millimeters is 3.5 inches?
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Decimal places
A whole number is called an integer
Consider this real number:
A number containing a portion of a
whole number is called a real number
4, 5, 8, 44, 103, 3,373, and
26,252 are examples of integers
3.274 is an example of a real number
In a real number, the values to the
right of the decimal point are called
decimal places
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Lesson topics
5.436
There are three decimal
places to the right of the
decimal point
With most CNC machines…
Metric system allows up to three
decimal places
Imperial system allows up to four
decimal places
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Fractional format
When using the Imperial measurement
system (not the Metric system)…
Some values may be specified
with fractions
Consider this fraction:
13/16
Pronounced as “thirteen-sixteenths”
But a CNC machine cannot
accept fractional format
Divide 13 by 16
Fractions must be converted to
decimal format
0.8125 (the result) is the
decimal format of 13/16
To convert a fraction to decimal
format, divide the numerator (top or
left number) by the denominator
(bottom or right number)
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Saying numbers out loud in a machine shop
In the Imperial measurement system:
1.0 : “one inch”
0.1 : “one-hundred-thousandths of an inch”
0.01 : “ten-thousandths of an inch”
0.001 : “one-thousandth of an inch”
0.0001 : “one tenth” (even though this value is
really one ten-thousandth of an inch)
More examples:
0.047 : “forty-seven thousandths”
0.250 : “two-hundred-fifty thousandths”
0.684 : “six-hundred-eighty-four thousandths”
1.455 : “one inch, four-hundred-fifty-five thousandths”
4.3723 : “four inches, three-hundred-seventy-two thousandths, and three tenths”
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Saying numbers out loud in a machine shop
In the Metric measurement system:
1.0 : “one millimeter”
0.1 : “one-hundred microns”
0.01 : “ten microns”
0.001 : “one micron”
More examples:
0.047 : “forty-seven microns”
0.250 : “two-hundred-fifty microns”
0.684 : “six-hundred-eighty-four microns”
1.455 : “one millimeter, four-hundred-fifty-five microns”
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Polarity
All values have a polarity (plus or minus)
With CNC machines, plus is always assumed
If no polarity sign is specified (+ or -), the
value is assumed to be positive
All values shown to this point have been positive
To specify a negative value, the minus sign (-) is used:
-0.003 (negative three thousandths of an inch)
When you subtract a number from a
smaller number, the result will be negative
5.002 - 5.006 = -0.004
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Lesson topics
Next topic: Blueprint reading
Copyright 2010
CNC Turning Center Setup and Operation
Lesson 1:
Basic machining practices required for turning centers
Shop math
 Summary
Most calculations required of setup people
and operators are pretty simple
The trick lies in doing simple calculations – over and
over again – with out making any mistakes!
Mistakes will, of course, result in scrap parts – or worse
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Lesson topics
Next topic: Blueprint reading
Copyright 2010