Here's a cool diagram showing you all the parts of a screw including head, drive, thread, pitch, major diameter, minor diameter, crest, thread angle, shank and more.
Not only are there many types of screws and screwheads, there’s an intricate number of different parts of a screw.
Check out our custom diagram above which clearly indicates each part.
Who knew there was so much involved in designing and making a screw.
Here are brief descriptions of each part.
Drive: This is the slot where your screwdriver tip goes. It’s also referred to as a screw head. There are many such options; accordingly there are many screwdriver tips you should have in your toolbox.
Head: The head is the top of the screw. It’s typically wider than the shank and thread. Heads can be flat or domed. Some have a small diameter in relation to the shank and others are very wide.
Thread length: The thread length is either full length or partial. Accordingly, there are full thread and partial thread screws.
Why would you use a partial thread screw? It’s stronger in the sense that the non-thread part is stronger without weak spots. When you need to bolt something together with maximum strength, a partial thread screw or bolt is best. Read all about this here.
Point: The point is obviously where the screw enters whatever material you’re putting the screw into. If no point (i.e. flat tip), it’s a bolt which requires a pre-made hole.
The thread: Amazingly, the thread has many components and varies among screws. There’s the thread angle which is how steeply it angles down.
There’s also distance in between threads that make a difference. This is the pitch. Some screws have thread that are small and close together. Other screws have larger threads spaced further apart (i.e. drywall anchors).
Screw thickness (minor and major diameter): There are two measurements when it comes to screw thickness. There’s minor and major diameters. The major diameter is the diameter at the thickest part of the thread (i.e. outer part of the thread, a.k.a. the crest). The minor diameter is the thickness at the base of the screw (imagine if the thread was stripped, the remaining shaft would be the minor diameter).
Crest: Crest is the tip and valley of the thread.