1. Threads and Fasteners

2. Purpose Machine screws Locking pins Adhesives Keys
To fasten objects together
Common Fasteners:
Nuts & bolts
Tapers
Rivets
Screws
Nails
Machine screws
Locking pins
Adhesives
Keys

3. Threads Course Threads, Fine Threads, Metric threads and whitworth.
Course and fine are common imperial
Metric is common
Whitworth is the old British standard

4. Course Threads Threads farther apart Deeper cut
Best used with soft materials
Aluminum
Brass
Copper
Plastic

5. Fine Threads Threads closer together More thread contact for length
Common in harder metals

6. Metric Has similar course and fine types Measured differently
Different head markings

7. Whitworth Threads Only found in old British cars
55° thread instead of standard 60 °

8. Thread classification
UNC Unified national course
UNF Unified national fine
Standard measurement
Measured in threads per inch
Metric
Measured by the distance in mm between the treads

9. Measuring Bolt Size = Major Diameter
Bolt head size = Distance between the flats of the hexagon

10. Measuring
Bolt length = the distance from the base of the head to the end of the thread
Thread pitch = Threads per inch & Distance between threads

11. Grade Tensile strength (pulling strength)
Amount of PSI the bolt can handle
Only accurate for bolts with a 1 inch diameter

12. Grade Grade stamped on top Imperial grade = number of lines + Two
Metric Grade is printed
5D, 8G, 10K, 12K.

13. Under load
When a bolt goes past its load capacity it reaches its elastic limit
After elastic limit the bolt stretches and looses strength

14. Torque Specs
All bolts on a vehicle have a special specification that they have to be tightened too.
Always look this up in the manual before tightening any thing

15. Flat Washers Used to make larger bearing surfaces for nuts to ride on
Stops nuts and bolts from becoming imbedded in soft materials

16. Lock Washers Prevents fastener from loosening Made from spring steel
Split and bent, cuts in to base material and fastener

17. Multiple Tooth Washer Solid piece
Has twisted teeth that dig in to fastener and base metal

18. Pins
Retains parts in a fixed position
Used for alignment

19. Cotter Pins
Used to hold nuts in position
Specifically Castle nuts

20. Snap Ring Clips in to groves to retain parts
Groves can either be external or internal

21. Keys Used to fix gears and pulleys to shafts
Cut in gear or pulley called the key seat
Cut in shaft called the key way

22. Adhesives Liquid or semi-liquid Prevents loosening Only one drip
Range from light to strong

23. Sealants Resistance from the elements
Oil, water, gas, grease, and salt