What Are the Differences Between a Set Screw and a Self-tapping Screw

What Are Set Screws Used For?

Also known as "headless screws," set screws belong to a very particular category of product. Indeed, they differ from classic screws because they lack a head and both ends are finished with threading.

The particular structure of this screw, and therefore the threading, allows two elements to be fastened together. Indeed, this type of mechanical element was designed specifically to ensure fastening when the incomplete threads of the screw penetrate the opening of the hole.

The threaded stud consists of three main elements:

• The root, the first threaded part that will be screwed into the blind hole;
• The central part, not threaded;
• The shank, the second and last threaded end where the nut and washer are fixed.

Set screws can have different types of tips or ends. For example, the first threaded part can have a larger diameter and pitch compared to other parts.

Therefore, there are different types of set screws on the market that meet the needs of various fields, from mechanics to construction to fastening.

In most cases, the most used set screws are made of steel. It is possible, therefore, to find them in raw steel, galvanized steel, and stainless steel.

During production, if requested, the mechanical element can be made with different characteristics from the standard but always in line with DIN or ISO regulations.

What Is a Self-tapping Screw?

As emphasized at the beginning, the choice of the screw to be used must be made by evaluating the conformation and composition of the elements to be fastened. Even within the class of set screws, it is possible to change the type of element in relation to the purpose of use.
The self-tapping screw is a type of stud used in the presence of blind holes and with more ductile materials, like wood or plastics.

Differences Between Set Screw and Self-tapping Screw

The difference between a set screw and a self-tapping screw is found in their application, that is, in the way they fit into the material.

Specifically, the self-tapping screw is inserted into a blind or through-hole and thus is "anchored" within the material where it will be fixed. This way, the screw requires access from only one side and occupies little space. It is not advisable to use it in case of frequent disassemblies, to avoid wearing out the threads of the nut.

In the case of the set screw, it will be inserted into the through-hole from the root side and will then be fastened with a nut from the shank side.
The use of this screw is recommended when the drilled material does not support frequent unscrewing. Set screws are therefore used in cases where it is not possible to use types of screws with a protruding head.

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