TECH 104 Technical Graphics Communication

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TECH 104 Technical Graphics Communication

• Week 10
• Working Drawings

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TECH 104 Technical Graphics Communication
First, heres what we talked about last
time Applying Tolerances

• Week 10 Working Drawings

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TECH 104 Technical Graphics Communication
Representing Tolerance Values
Tolerance is the total amount a dimension
may vary and is the difference between the
maximum and minimum limits. (A) Tolerance
.04 (B) Tolerance .006
Tolerances are represented as Direct Limits
(A) or as Tolerance Values (B).
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Important Terms of Toleranced Parts
Nominal Size is used to describe the general size
(usually in fractions).
Basic Size theoretical size used as a starting
point for the application of tolerances (written
in decimals).
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Important Terms of Toleranced Parts
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Important Terms of Toleranced Parts
(The minimum clearance or maximum interference).
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Important Terms of Toleranced Parts
Least Material Condition (LMC) The condition of a
part when it contains he least amount of
material possible.
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Important Terms of Toleranced Parts
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Fit Types
A Clearance Fit occurs when two toleranced mating
parts will always leave a space or clearance when
assembled.
An Interference Fit occurs when two toleranced
mating parts will always interfere when assembled.
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Functional Dimensioning
Then, the material around the holes
is dimensioned (at a much looser tolerance).
Functional features are those that come in
contact with other parts, especially moving
parts. Holes are usually functional features.
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Occurs when dimensions are taken from opposite
directions of separate parts to the same point of
an assembly.
Tolerance Stack-up
AVOID THIS!!!
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication
Avoiding Tolerance Stack-up
Tolerance stack-up can be eliminated by
careful consideration and placement of
dimensions. (Dimension from same side).
Week 10 Working Drawings
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TECH 104 Technical Graphics Communication

• Todays Lecture - Week 10
• Working Drawings

Generally, a complete set of Working Drawings for
an assembly includes
1.) Detail Drawings of each non-standard part.
2.) An Assembly or Subassembly drawing showing
all the standard parts in a single
drawing.
3.) A Bill of Materials (BOM).
4. A Title Block.
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• A Detail Drawing of a Single
• Part Called a Lever

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• Assembly Drawing of a Piston Rod containing 8
  parts.

An assembly drawing normally consists of the
following 1. All parts drawn in their operating
position 2. A parts list or Bill of Materials
(BOM) 3.Leader lines with balloons indicating
all parts. 4. Machining and assembly instructions
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• Detail Drawing of the retainer ring used to
  fasten the rod to the piston.

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Multiview Sectioned Assembly Drawing of a Spring
Pack containing

• Drawing Number

Part Numbers
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TECH 104 Technical Graphics Communication

• Pictorial Assemblies

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TECH 104 Technical Graphics Communication

• Pictorial Assemblies

Technical Illustration (Exploded) Assembly
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TECH 104 Technical Graphics Communication
contain...

• Title Blocks

• Name Address of Company
• Title of the Drawing
• Drawing Number
• Names and dates of drafters,
• checker, issue date ,
• contract number, etc.
• E. Design Approval
• F. Additional Approval Block
• G. Drawing Scale
• H. Federal Supply Code for
• Manufacturers
• J. Drawing Sheet Size
• K. Actual or estimated weight
• L. Sheet Number

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TECH 104 Technical Graphics Communication

• Parts Lists

The information normally included in a parts list
is as follows 1. Name of the part. 2. A detail
number for the part in the assembly. 3. The part
material, such as cast iron or bronze. 4. The
number of times that part is used in the
assembly. 5. The company assigned part
number. 6. Other information, such as weight,
stock size, etc.
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TECH 104 Technical Graphics Communication
Record any changes - Found in upper-right corner

• Revision Blocks

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TECH 104 Technical Graphics Communication

• General tolerance note for inch and millimeter
  dimensions

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• ANSI drawing sheets with zones located on the
  border.

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TECH 104 Technical Graphics Communication

• Tabular Drawings

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Also in Todays Lecture - Week 10 Fastening
Devices

• Fastening is a method of connecting or joining
  two or more parts together, using devices or
  processes.
• Mechanical Fastening Process that uses
  manufactured devices (Nuts and Bolts)
• Bonding Using material (Glue, Welding)
• Forming Using component shape itself (HVAC,
  Tupperware, Velcro)

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Threaded Fasteners

• First Application of a screw thread was developed
  by Archimedes to lift water.
• 1800s Joseph Whitworth English Standard Screw
  Threads
• 1864 US Screw Thread Standard
• 1946 ISO Develops Metric Standard
• 1948 US Develops Unified Standard

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• Standard Thread Notations

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TECH 104 Technical Graphics Communication

• Specifying Tap Drill Size

A Tap is a tool used to make threads in holes. A
Die is used to make external threads.
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TECH 104 Technical Graphics Communication

• Thread Representation

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TECH 104 Technical Graphics Communication

• General Types of Fasteners

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TECH 104 Technical Graphics Communication

• Finished vs.
• Unfinished Bolts

The difference between a finished and Unfinished
hex head bolt is a washer Under the head of the
finished bolt.
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TECH 104 Technical Graphics Communication

• Nuts

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TECH 104 Technical Graphics Communication

• Cap Screws

Notice the chamfer (Also found on bolts).
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TECH 104 Technical Graphics Communication

• Machine Screws

Machine Screws are finished with flat bottoms
instead of chamfered corners. A ½ Hex Head
Machine Screw is used on this weeks assembly
drawing.
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TECH 104 Technical Graphics Communication

• Set Screws

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TECH 104 Technical Graphics Communication

• Shoulder Screw

Check Appendix 33 for the dimensions of the
shoulder screw required for this weeks assembly
drawing
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TECH 104 Technical Graphics Communication

• Retaining Rings

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TECH 104 Technical Graphics Communication

• Lock Washers

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TECH 104 Technical Graphics Communication

• Pin Types

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TECH 104 Technical Graphics Communication

• Standard Key Types

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TECH 104 Technical Graphics Communication

• Rivets

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TECH 104 Technical Graphics Communication

• Rivets

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TECH 104 Technical Graphics Communication

• Springs

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TECH 104 TechnicalGraphics Communication
This Weeks Drawing
Create a complete set of Working Drawings
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TECH 104 Technical Graphics Communication

• Week 11
• Pictorial Drawings