Per què els cargols tenen tants tipus de discs?
Why do screws have so many Drive types
一、What are the types of screwdrivers?
Types of Screwdriver.
Flat Head (or Slotted Head) Screwdriver.
Hex Screwdriver or Hexagon Screwdriver.
二、Why are there round, cylindrical and conical "Drive types"?
The first (with or without nuts): screws, bolts
The second (convex but not protruding): countersunk head, unsunk head
The third：cross, slot, inner hexagon, hexagon, special shape
Bolts, nuts, and connection diagrams
三、Socket screws, bolts and allen wrenches
A lot of hexagon socket screws are used in bicycles