The “self-tapping screws” are normally used on sheet metal surfaces and similar materials. They are often used for roof cladding and for mounting metal and PVC windows. The self-tapping screws can be inserted into an existing hole, or alternatively they may require the use of a drill.
When you buy self-tapping screws you will have to choose the exact size, without necessarily having to go to the hardware store and try to make them understand the size you need with your fingers. If you have the necessary information, you can buy all the screws you need, in store or online. Read on to understand what information you need and how to get it.
- Self-tapping screws are often used for roofing and for fixing air conditioners.
- If you are unsure which size to choose, buy an assorted set of self-tapping screws in different sizes.
- Before buying self-tapping screws you need to check criteria such as size, head shape and understand if you need to use a drill.
The best self-tapping screws on the market: our selection
There are packs on the market that are ideal for construction professionals as they contain loose screws of one size. In our selection, however, we will focus more on proposals for do-it-yourself. Let’s see our selection:
- The best set of M2 screws
- The best black galvanized screws
- The best set of M4 screws
- The best bodywork set
The best set of M2 screws
Asiv offers a set consisting of 800 M2 self-tapping screws, inside a practical plastic organizer with modular dividers. These are nickel-coated steel screws with cross head, perfect for iron and wood. They count 100 units for each of the 8 sizes supplied: 4, 5, 6, 8, 10, 12, 16 and 20 mm in length. They are quite small but buyers do not complain about them, rather they appreciate the quality and convenience.
The best black galvanized screws
AUPROTEC self-tapping screws are sold in sets of 100 for each size (3.9 mm, 4.2 mm and 4.8 mm) and with lengths ranging from 9.5 to 48 mm. They are stainless steel screws with galvanic zinc coating, black in color; the head is flanged with a hex socket, and conforms to ISO 7049 standards. They may not be cheap, but according to reviewers, these are high quality screws.
The best set of M4 screws
Avis M4 self-tapping screws are sold in a plastic organizer, and are suitable for metal, wood and drywall. They are gilded galvanized iron screws with flat head and cross recess, with lengths of 16, 20, 25, 30, 35, 40, 45 and 50 mm. The one under consideration is certainly a complete and versatile set of M4 screws, of which buyers are quick to confirm the quality.
The best bodywork set
CCLIFE offers a set including 85 self-tapping cross-headed screws, together with the same number of black steel nuts. These are brass screws of 3, 4, 5 and 6 mm in diameter, with lengths of 8, 16, 12 and 20 mm respectively; they are mainly suitable for bodywork and iron sheets. The 170 pieces of the set are supplied in an organizer and divided by size.
Shopping Guide: Everything you need to know about self-tapping screws
Self-tapping screws are essential elements for fixing any type of appliance, such as air conditioners. They are highly appreciated in the automotive and, more generally, mechanical fields for their grip and resistance. Read on to find out which type of self-tapping screws are best suited to your needs.
What are self-tapping screws?
There is also the so-called self-drilling screw, which makes its way into the sheets thanks to its end that resembles the tip of a drill. The self-tapping screw is widely used in roofs, PVC or aluminum windows and in general for metal constructions. The approval of self-tapping screws follows the DIN 267 standard regarding the resistance of materials.
What are self-tapping screws used for?
- Support and anchoring systems
- Metal profiles
- Union of metal sheets
- Joining metal sheets with wooden sheets
- Metal doors
- Garage doors
- Roofing and cladding
Can self-tapping screws also be used for wood?
Of course, this doesn’t stop us from using a self-tapping screw to join a metal sheet with a wooden surface. However, it is not at all a good idea to use a self-tapping screw on a material such as chipboard. In general, it all depends on the consistency and compactness of the wood. Wood screws have a different and wider thread, which allows you to have more grip on this material.
What is the difference between the different self-tapping screw formats?
The self-tapping screw has a fine thread, which is ideal for drilling into metal sheets. There are also other screws that are not properly “self-tapping”, but we are talking about them here because they are used on the same type of material: sheet metal. These are the self-drilling screws, which we have previously mentioned, which have an end similar to the tip of a drill. Summing up:
- Self-tapping . It fits into a hole previously made with the drill.
- Self-drilling . As the name indicates, the screw itself opens the hole during “screwing”
- With finish . The most common finishes for screws are generally galvanized and bichromate. The latter is the finish used for wood screws, which have a yellow or golden color.
How do you choose the number (dimensions) of self-tapping screws in relation to the thickness of the sheet?
The products in our selection contain an assortment of different types of sheet metal screws. For those who want a more specific product, however, it is possible to purchase a package with pieces of a particular format suitable for their needs. In this case it is essential to measure the thickness of the sheet. You can see the references in this table:
|Screw size (nº)||Diameter (mm)||Sheet thickness (mm)|
|Nº 2||Ø 2.2||Up to 1.50 mm|
|No. 4||Ø 2.9||Up to 2.50 mm|
|No. 6||Ø 3.5||Up to 6 mm|
|Nº 7||Ø 3.9||Up to 6 mm|
|Nº 8||Ø 4.2||Up to 6 mm|
|No. 10||Ø 4.8||Up to 10 mm|
|No. 12||Ø 5.5||Up to 10 mm|
|No. 14||Ø 6.3||Up to 10 mm|
What material are self-tapping screws made of?
- A2 type steel . It is a stainless steel used for many tools, and which is technically called AISI 304, or more simply 304 steel.
- A4 type steel . Self-tapping screws made with this type of steel are those that offer the greatest degree of resistance to corrosion, since the alloy used contains a higher percentage of molybdenum. The technical name of this type of steel is AISI 316.
What are the instructions to follow to use self-tapping screws?
What else are self-tapping screws called?
- Self-tapping screws
- Bodywork screws
- Sheet metal screws
- Self-drilling screws
Buying a screw is no longer like it used to be. In fact, once upon a time it was normal to ask the clerk about the hardware store, making use of his patience and experience. We can now purchase a pack of self-tapping screws without moving from our desk. However, in the absence of advice and recommendations from the hardware store, it is essential to inquire about the most important aspects, before buying. For example:
- Dimensions of the screws
- Screw material
- With or without hole
- Surface material to be screwed on
- Quantity of screws
Dimensions of the screws
Surely there is someone who still goes to the hardware store to buy screws “of this size”. However, this method has never been effective. Units of measurement were invented for a reason, and in the case of a sale, all information about the products offered is usually available. Self-tapping screws, like any other type of screws, must be of the right thickness and length for our needs.
If you don’t know how to measure a screw, remember that it only considers the space between the tip and the bottom of the head which is the part that remains outside the surface. As for the countersunk screws, which remain flush with the surface, the head is included in the measurement, then the whole screw is measured. When you find the double quote symbol (“) next to the number, it means the measurement is in inches.
The screws can be made from different types of stainless steel. As far as self-tapping screws are concerned, the differences are mainly due to the type of alloy used and the heat treatment to which the screws are subjected. All parameters are expressed in DIN 267. Make sure your screws meet the requirements of this standard.
As we have seen, there are mainly two types of stainless steel: the most resistant is the A4 type steel, also known as AISI 316. It has a marked resistance to the effects of corrosion, a truly advantageous feature for the screws used to fix surfaces exposed to the water and atmospheric agents, as in the case of roofing.
With or without hole
If there is already a hole on the surface on which we will apply the self-tapping screw, it will only be necessary to choose a screw that has the appropriate diameter and length. Instead, if it is a material that does not require the intervention of a drill, we can try with a self-drilling screw for metal sheets. In this case it is the screw itself that makes the hole.
Self-drilling screws can be applied to different surfaces. Purists may point out that self-drilling screws are not exactly self-tapping screws, but these screws are also used for sheet metal. However, with a quick search on the internet you will also find self-drilling screws for metal sheets.
Surface material to be screwed on
The thickness and hardness of the material to be fixed will determine the choice of the type of self-tapping screws to use. In general, as the name itself indicates, these are screws that are applied to metal sheets. Of course, they can also be used for wood – except for chipboard – but it is always advisable to use specific screws for each type of material.
Another aspect to consider is the weight that each screw will have to bear. Let’s not forget that self-tapping screws are often used to fix appliances such as air conditioners and others of similar volume. DIN 267 provides information about the “minimum breaking torque” which determines the strength of the screw.
Quantity of screws
It is never a bad idea to calculate and figure out how many screws you will need, approximately, before making the purchase. Normally you need screws of different thicknesses and lengths – if this is your case, we recommend that you purchase a set of screws that includes an assortment of different sized pieces.
The screws in our selection are meant for the average buyer, who is dedicated to do-it-yourself. If, on the other hand, you are a professional in the construction sector, the amount of screws to buy will be a factor that should not be underestimated. In this case, instead of choosing an assorted package, it will be better to buy a package containing large quantities of the screws of specific dimensions, the ones you use most often.