Threads, Fasteners, and Springs Chapter 11

2 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Objectives Define and label the parts of a screw thread Identify various screw thread forms Draw detailed, schematic, and simplified threads Define typical thread specifications

3 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Objectives (cont.) Identify various fasteners and describe their use Draw various screw head types Draw springs

4 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Understanding Threads and Fasteners There are three basic applications for screw threads: To hold parts together To provide for adjustment between parts To transmit power

5 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms

6 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Screw thread – a ridge of uniform section in the form of a helix on the external or internal surface of a cylinder External thread – a thread on the outside of a member Internal thread – a thread on the inside of a member

7 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Major diameter – the largest diameter of a screw thread Minor diameter – the smallest diameter of a screw thread

8 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Pitch – the distance from a point on a screw thread to a corresponding point on the next thread measured parallel to the axis Pitch (P) equals 1 divided by the number of threads per inch

9 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Pitch diameter – the diameter of an imaginary cylinder passing through threads where the widths of the threads and the widths of the spaces would be equal Lead – the distance a screw thread advances axially in one turn

10 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Angle of thread – the angle between the sides of the thread measured in a plane through the axis of the screw Crest – the top surface joining the two sides of a thread Root – the bottom surface joining the sides of two adjacent threads

11 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Side – the surface of the thread that connects the crest with the root Axis of screw – the longitudinal centerline through the screw Depth of thread – the distance between the crest and the root of the thread measured normal to the axis

12 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Terms Form of thread – the cross section of thread cut by a plane containing the axis Series of thread – standard number of threads per inch for various diameters

13 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Forms Typical thread forms include: Sharp-V thread (60 degrees) American national thread Unified thread Unified extra fine thread series Metric thread Square thread Acme thread

14 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Forms Typical thread forms (cont.) Standard worm thread Whitworth thread Knuckle thread Buttress thread

15 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Screw Thread Forms

16 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thread Pitch

17 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Right-hand and Left-hand Threads

18 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Single and Multiple Threads Single threads are composed of one ridge and the lead is equal to the pitch Multiple threads are composed of two or more ridges running side by side

19 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Single and Multiple Threads

20 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thread Fits ANSI has established 3 classes of fit: Class 1 – when clearance between mating parts is essential Class 2 – high quality for the bulk of interchangeable screw thread work Class 3 – exceptionally high quality recommended only when high cost of precision is warranted

21 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thread Fits Some specialized metric thread applications are specified by: Tolerance grade Tolerance positions Class Length of engagement

22 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Methods for Drawing Thread There are three methods of representing screw threads on drawings: Schematic Simplified Detailed

23 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Methods for Drawing Thread

24 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Methods for Drawing Thread

25 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Methods for Drawing Thread

26 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thread Notes ASME/ANSI Y “Screw Thread Representations” is a standard for representing, specifying, and dimensioning screw threads on drawings These same notes or symbols are used in correspondence, in records, and in specifications for parts, taps, dies, tools, and gages

27 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thread Notes

28 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Thread Notes

29 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. External Thread Symbols

30 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Internal Thread Symbols

31 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Detailed Representation

32 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Detailed Representation

33 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Use of Phantom Lines

34 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Threads in Assembly

35 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Pipe Thread Representation

36 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Bolts, Studs, and Screws

37 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Types of Screw Heads

38 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Tapped Holes The bottom of a drilled hole formed by the point of a twist drill is cone shaped The thread length is the length of full or perfect threads The tap drill depth does not include the cone point of the drill

39 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Tapped Holes

40 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Standard Bolts and Nuts Standard bolts and nuts have characteristics determined by: Bolt types Finish Proportions Threads Thread lengths Bolt lengths

41 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Specifications In specifying bolts, the following information must be covered in order: Nominal size of bolt body Thread specification or thread note Length of bolt Finish of bolt Style of head Name

42 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Locknuts and Locking Devices

43 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Standard Cap Screws

44 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Standard Machine Screws

45 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Standard Set Screws

46 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Standard Wood Screws

47 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Miscellaneous Fasteners

48 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Keys Keys are used to prevent movement between shafts and wheels, couplings, cranks, and similar machine parts attached to or supported by shafts

49 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Keys

50 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Machine Pins Machine pins include taper pins, straight pins, dowel pins, clevis pins, and cotter pins

51 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Rivets Rivets are permanent fasteners used to hold sheet metal or rolled steel together

52 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Springs A spring is a mechanical device designed to store energy when deflected and to return the equivalent amount of energy when released Springs are classified as: Helical springs Flat springs

53 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Helical Springs Helical springs have three types: Compression springs Extension springs Torsion springs

54 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Helical Springs

55 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Compression Springs

56 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Extension Springs

57 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Torsion Springs

58 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. Flat Springs