Screws and bolts

Screws are used to fasten things against one another.

1. Countersunk screws 🔗

The bottom of the head, as it connects to the body of the screw, can either be flat and sit flat on top of the material, or be countersunk (sv: försänkt) and sit flush with the surface of the material

An alternate use for a countersunk screw is to center something with a round hole against something else. However this risks putting strain on the screw head in a way that is probably not very good.

2. Slot 🔗

The slot determines what screwdriver is used to drive the screw and how good a grip the intended screwdriver gets.

  • Flat: just a flat screwdriver. Poor grip. Pretty uncommon in this day and age.
  • Cross: more fancily called a Phillips, it's a plus-sign. Probably the most common slot.
  • Pozidriv: a cross with a smaller cross rotated 45 degrees inside. Looks a lot like a regular cross, but grip will be lacking if using one. Deceptive little bastards.
  • Hex: a hexagon! Usually driven with an allen wrench, commonly found in IKEA furniture.
  • Torx: a hexagram! Relatively common and gets amazing grip.
  • Tri-point: looks like a Y. Used in equipment by manufacturers who resent the right to repair such as Nintendo.

3. Thread 🔗

Thread (sv: gänga) is the tracks around the screw that guide the screw into position. They are considered fine if their pitch is tight. Bolts are usually a lot finer than screws, as screws need to self-tap what they're going into.

4. Screws vs bolts 🔗

Bolts (sv: bult) are usually distinguished from screws in that they are made to fit into a pre-tapped hole or a nut, whereas screws self-thread the hole, albeit not necessarily self-drilling. The technical disinction is a bit unclear, but that's for Wikipedia to care about.

5. Nuts 🔗

A nut (sv: mutter) is what a bolt goes into!

6. Washers 🔗

A washer (sv: bricka) helps distribute force, preventing damage against both screw and material.

7. Metric screw standards 🔗

Metric screw standards, especially bolts, are labelled 'MN' e.g. M2, M10 where the number represents the diameter of the screw in millimeters. Although often omitted, a thread pitch can be specified in millimeters with a postfix of '×N', e.g. 'M2.5×0.5'. A length is often specified in marketing using the same format however, e.g. 'M3×10'. If this was a thread pitch denomination, it would of course be a very silly one as M3 screws are usually not so long that there'd be more than one or two total revolutions of the thread.

Commonly used sizes are:

  • M2
  • M3
  • M4
  • M6
  • M8
  • M10
  • ...

Pok3r-case 60% keyboards use M2.5 screws. It's awful.

8. Funky screws 🔗

  • Hexagonal heads: Hex bolts usually have no slot and are instead turned with a wrench.

  • Train bolts: train bolts have a rounded head that cannot be gripped by mortal hands and no slot, meaning they can only be tightened by turning the nut.

  • Set screws: also known as grub screws (sv: stoppskruv), they are headless. They may have a slot in the body of the screw, usually a hexagonal one.

9. See also 🔗