1. TECH 104 – Technical Graphics Communication
Week 10:
Working Drawings

2. TECH 104 – Technical Graphics Communication
First, here’s what we talked about last time…
Applying Tolerances
Week 10: Working Drawings

3. Representing Tolerance Values
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

4. Important Terms of Toleranced Parts
TECH 104 – Technical Graphics Communication
Important Terms of Toleranced Parts
A System is two or more mating 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

5. Important Terms of Toleranced Parts
TECH 104 – Technical Graphics Communication
Important Terms of Toleranced Parts
Limits – the maximum and minimum sizes shown by the tolerance dimension.
The large value on each part is the Upper Limit, the small value = Lower Limit.
Actual Size is the measured size of the finished part after machining.
Week 10: Working Drawings

6. Important Terms of Toleranced Parts
TECH 104 – Technical Graphics Communication
Important Terms of Toleranced Parts
Allowance – the tightest fit
between two mating parts.
(The minimum clearance or maximum interference).
Week 10: Working Drawings

7. Important Terms of Toleranced Parts
TECH 104 – Technical Graphics Communication
Important Terms of Toleranced Parts
Maximum Material Condition (MMC)
The condition of a part when it contains
the greatest amount of material.
Least Material Condition (LMC)
The condition of a part when it contains
he least amount of material possible.
Week 10: Working Drawings

8. Important Terms of Toleranced Parts
TECH 104 – Technical Graphics Communication
Important Terms of Toleranced Parts
Piece tolerance
The difference between the upper and lower limits of a single part
(.002 on the insert in this example, .004 on the slot.).
System tolerance
The sum of all the piece tolerances.
For this example (.006)
Week 10: Working Drawings

9. Fit Types: TECH 104 – Technical Graphics Communication
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

10. Functional Dimensioning
TECH 104 – Technical Graphics Communication
Functional Dimensioning
Functional Dimensioning begins with tolerancing the most important features.
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

11. Tolerance Stack-up AVOID THIS!!!
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
Dimensioned
from the
left.
Dimensioned
from the
right.
AVOID THIS!!!
Week 10: Working Drawings

12. Avoiding Tolerance Stack-up
TECH 104 – Technical Graphics Communication
Avoiding
Tolerance
Stack-up
Better still, relate the two
holes directly to each other,
not to either side of the part.
The result will be the best
tolerance possible of ±0.005.
Tolerance stack-up can
be eliminated by careful
consideration and
placement of dimensions.
(Dimension from same side).
Week 10: Working Drawings

13. Today’s Lecture - Week 10: Working Drawings
TECH 104 – Technical Graphics Communication
Today’s 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.

14. A Detail Drawing of a Single Part Called a Lever

15. 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

16. Detail Drawing of the retainer ring used to fasten the rod to the piston.

17. Drawing Number Part Numbers Multiview Sectioned Assembly
Drawing of a Spring Pack containing…
Drawing Number
Part Numbers

18. Pictorial Assemblies TECH 104 – Technical Graphics Communication
Sectioned Assembly
Pictorial Assemblies

19. Pictorial Assemblies TECH 104 – Technical Graphics Communication
Technical Illustration (Exploded) Assembly

20. Title Blocks …contain... TECH 104 – Technical Graphics Communication
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

21. Parts Lists TECH 104 – Technical Graphics Communication
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.

22. Revision Blocks TECH 104 – Technical Graphics Communication
Record any changes -
Found in upper-right corner
Revision Blocks

23. General tolerance note for inch and millimeter dimensions
TECH 104 – Technical Graphics Communication
General tolerance note for inch and millimeter dimensions

24. ANSI drawing sheets with “zones” located on the border.

25. TECH 104 – Technical Graphics Communication
Tabular Drawings

26. Also in Today’s 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)

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

28. Standard Thread Notations:
Form Chart
Standard Thread Notations:
Internal Threads
External Threads

29. Specifying Tap Drill Size:
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.

30. Thread Representation:
TECH 104 – Technical Graphics Communication
Thread Representation:

31. General Types of Fasteners:
TECH 104 – Technical Graphics Communication
General Types of Fasteners:

32. Finished vs. Unfinished Bolts:
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.

33. TECH 104 – Technical Graphics Communication
Nuts:

34. Cap Screws: TECH 104 – Technical Graphics Communication
Notice the chamfer (Also found on bolts).

35. A ½” Hex Head Machine Screw is used on this week’s assembly drawing.
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 week’s assembly drawing.

36. TECH 104 – Technical Graphics Communication
Set Screws:

37. Shoulder Screw: TECH 104 – Technical Graphics Communication
Check Appendix 33 for the dimensions of the shoulder screw
required for this week’s assembly drawing

38. TECH 104 – Technical Graphics Communication
Retaining Rings:

39. TECH 104 – Technical Graphics Communication
Lock Washers:

40. TECH 104 – Technical Graphics Communication
Pin Types:

41. TECH 104 – Technical Graphics Communication
Standard Key Types:

42. TECH 104 – Technical Graphics Communication
Rivets:

43. TECH 104 – Technical Graphics Communication
Rivets:

44. TECH 104 – Technical Graphics Communication
Springs:

45. This Week’s Drawing TECH 104 – Technical Graphics Communication
Create a complete set
of Working Drawings

46. TECH 104 – Technical Graphics Communication
Week 11:
Pictorial Drawings