All you want to know about self-tapping screws is here

Self-tapping screws are different from regular screws in that they tap themselves when screwed into plastic, wood or metal.

1. How to determine the screw size I need?

In most cases, test and error will help you find the right size screw. You should consider the thickness of the material and the desired finish. Also note that it is easier to make the hole bigger than it is to make it bigger with a big screw.

2. Does the size of the screw matter?

Choosing the wrong size screw can lead to danger. If the screw is too long or too small for your job, then it's not for you. If the screw does not disappear completely (depending on the head type) or is too loose, it should be removed and a more suitable screw should be used.

3. Can metal screws in wood be used?

On the application, start with the correct type of screw. Wood screws can be used for wood, but because of their flexibility, wood screws are more suitable.

4. Can wood screws be used on metal plates?

cannot. Tensile strength of different metal screws. Use only metal screws, not wooden dowels.

5. Can outdoor screws be used?

If the screw is galvanized, or marked as "outdoor use", it can be used indoors or outdoors. Electroplated screws have a protective layer against rain and are not prone to rust or corrosion.

6. Do self-tapping screws still need a screwdriver?

Probably. That depends on what material you screw in.

7. How to tighten or loosen the screws?

Make sure to turn the screw clockwise to tighten and counterclockwise to loosen. Left, right.

8. How tight are the screws?

Tighten or to the torque specified by the manufacturer. Various head screws allow more or less torque to be applied.

9. The matching of drill screw and screw size, the matching formula of screw and drill bit?

Too bad there is no formula to match screw size and drill bit. The size of the drilled hole depends on whether there is hardwood, softwood, or raw plug in the drilled hole. First try a smaller drill to test if it fits, and if so, increase the size of the drill. Remember, drill bits are made by material, so you can't use woodworking bits for metal or masonry work.