Understanding Dual Input Set Screw Sizes: A Comprehensive Guide

Set screws are used to secure an object within or against another object, such as fixing a pulley or gear to a shaft. Unlike regular screws, set screws exert pressure at the tip to hold objects in place. They are often headless and threaded along their entire length, sitting entirely inside the hole of the first object and pressing against the second object. Set screws are available in a variety of standard threads and lengths, including 2-56, 8-32, 1/4-20, M2, M4, and M6 threads. They can be made from various materials such as stainless steel, nickel alloy, brass, and plastic, each offering different advantages in terms of corrosion resistance, conductivity, and weight.

Stainless steel set screws with hex sockets on one or both ends

If you're looking for stainless steel set screws with hex sockets on one or both ends, there are a variety of options available. These screws are designed for convenience, with hex-key sockets that eliminate the need for pliers and reduce the risk of ruining the threads.

Double-Ended Set Screws

Double-ended set screws feature a hex-key socket in both ends and are typically made of stainless steel. They are available in various standard threads and lengths, including 8-32 and M4. These screws are sold in packages of 10 and are ideal for applications where fine adjustment is needed.

Nylon-Tipped Set Screws

Nylon-tipped set screws, such as the SK-NYT-832 Set, feature a nylon tip on one end and a hex-key socket on the other. These screws are commonly used in optical mounts and are available in lengths such as 0.25 inches (6.35 mm). They are sold in packages of 10.

Stainless Steel Screw Refill Packs

Stainless steel screw refill packs offer a broad selection of threads and lengths for socket-head cap screws and cup-point set screws. These screws are made of stainless steel and are available in packages of 25 or 50. They can be used alone or to replenish refillable screw kits.

In addition to the options above, there are also stainless steel set screw assortment kits available from various manufacturers. These kits typically include a variety of sizes and come in a compartmented plastic case for organised storage. The assortment kits are ideal for those who need a range of screw sizes for different applications.

Set screw tip types: cup, flat, oval, cone, extended, etc

Set screws are fastening devices that use compressive force to secure objects within each other. They are inserted into threaded holes on the mating part and are commonly used in mechanical applications to affix gears, collars, or pulleys to a shaft. The selection of set screw types depends on the grip strength required, the need to minimise surface damage, and whether the connection should be permanent or adjustable. Here is a detailed overview of the different set screw tip types:

Cup

Cup point set screws are the most commonly used type because of their versatility. They offer a strong grip and are used when the screw needs to dig into the mating part. The cup provides enough grip without damaging the shaft. Cup point set screws are used in applications such as securing machine components onto shafts, including collars, gears, and knobs.

Knurled Cup

Knurled cup point set screws are similar to cup point set screws, but the surface that contacts the mating part is knurled. This helps the screw bite into the mating part. Knurled set screws are used in high-vibration applications like motors or machinery.

Flat

Flat point set screws have a flat end that presses flat against the surface of the mating part without biting into it. They are used when frequent adjustments are needed or when the point must be flush against the surface. Flat point set screws are used to adjust a collar on a shaft or when it needs to be repositioned without damaging the shaft.

Oval

Oval point set screws have a concave, rounded, oval-shaped point that reduces surface damage. Like flat point set screws, they are used when frequent readjustment is necessary. The oval shape allows the screw point to press against mating surfaces at slightly different angles.

Cone

Cone point set screws, also known as conical point set screws, have a sharp, pointed end that provides high holding power because the point deeply penetrates the mating part. These screws are typically used for permanent applications, such as setting a machine tool in relation to a workpiece or aligning gears to a shaft.

Extended

Extended set screws, also known as dog-point set screws, have a protruding tip that locks within a mating hole or slot to keep parts aligned. The extended tip is typically as long as the screw's diameter. They are used in applications where the set screw will mate into a predrilled hole, such as with set screw collars, which locate components on a shaft, such as bearings.

Set screw drives: hex, square head, slot, recessed, etc

Set screws are available in a variety of drives, each with its own unique characteristics and applications. Here is an overview of some common set screw drives:

Hex Drive

The hex drive, also known as the hex socket or Allen key drive, features a hexagonal recess in the screw head. It is designed to be used with a hex key, hex wrench, or Allen wrench. The hex drive provides the advantage of being able to apply higher torque without damaging the screw head. It is commonly used in applications where precision and a secure fit are important, such as in the automotive and aerospace industries.

Square Head Drive

The square head drive, also known as the Robertson drive, has a square-shaped socket in the screw head. It was invented by P.L. Robertson in 1908 and is particularly popular in Canada. One of its advantages is that the tapered socket tends to retain the screw, making it easier to use with one hand. Square head drives are commonly used in woodworking, construction, and electrical applications.

Slot Drive

The slot drive, also known as the flat-blade or flat-head drive, is the simplest and oldest type of screw drive. It features a single horizontal indentation in the screw head and is driven by a flat-bladed screwdriver. While it is commonly found in existing products and simple carpentry work, it is not suitable for power tools as the driver tends to cam out and damage the screw.

Recessed Drive

Recessed drives, such as the Supadrive, Pozidriv, and Phillips, feature a cross-shaped recess in the screw head. The Supadrive is an improved version of the Pozidriv, with larger secondary blades and better torque performance. The Phillips drive, on the other hand, is known for its tendency to cam out at lower torque levels. Recessed drives are commonly used in electrical devices and aftermarket serviceability.

Torx Drive

The Torx drive, also known as the star drive, has a star-shaped recess with six rounded points. It was designed to prevent cam-out and reduce operator fatigue. A security variant, known as the pin Torx or Torx Plus Tamper-Resistant, features a small pin in the center of the recess, making it more tamper-resistant. Torx drives are commonly used in the automotive and electronics industries.

Set screw materials: stainless steel, nickel alloy, brass, plastic, etc

Set screws are available in a variety of materials, each with its own unique properties and applications. Here is an overview of some common set screw materials:

Stainless Steel

Stainless steel set screws are known for their corrosion resistance and durability. They are commonly used in marine and saltwater environments due to their ability to resist corrosion. 316 stainless steel offers superior corrosion resistance compared to 18-8 stainless steel, making it ideal for harsh or marine environments. Stainless steel is also used for decorative applications as it typically has a clean silver colour. However, it should not be used with aluminium as galvanic corrosion may occur.

Nickel Alloy

Nickel alloy set screws offer excellent corrosion resistance, especially in saltwater and acidic environments. They are more corrosion-resistant than stainless steel and are often used in applications where salt water is present.

Brass

Brass set screws are corrosion-resistant in wet environments, making them suitable for plumbing applications. They are non-magnetic, electrically conductive, and non-magnetic. Brass is a soft material, so it may not be suitable for all applications.

Plastic

Plastic set screws are chemical-resistant, lightweight, and non-conductive, making them ideal for electrical applications. However, they may expand when exposed to moisture, so this should be considered when selecting a set screw material.

When choosing a set screw material, it is important to consider the specific application and environmental conditions. Each material has unique properties that make it suitable for certain situations. Additionally, it is generally recommended to perform an exact or matching swap when replacing a set screw, especially when dealing with stainless steel or specific bolt grades.

Set screw sizes: #10-24 x 3/8, #10-32 x 1/2, #6-32 x 3/16, etc

Set screws are available in a variety of sizes and measurements, which can be confusing when selecting the right one for your project. The numbers on set screws, such as #6, #8, #10, etc., refer to the diameter of the screw, with higher numbers indicating larger diameters.

For example, a #10-24 x 3/8 set screw has a diameter of #10 (approximately 0.1900 inches) and a thread count of 24 threads per inch. The length of the screw is 3/8 of an inch. This particular size is commonly used for smaller applications, such as securing hardware on electronics or hobby projects.

A #10-32 x 1/2 set screw also has a diameter of #10, but with a finer thread, resulting in 32 threads per inch. The length of this screw is 1/2 an inch, making it slightly longer than the previous example. This size is also commonly used for various applications, including electronics and light-duty fastening.

A #6-32 x 3/16 set screw has a smaller diameter of #6 (approximately 0.1360 inches) and a thread count of 32 threads per inch. The length of this screw is 3/16 of an inch, making it shorter than the previous examples. This size is often used for applications where a smaller screw is required, such as small electronics or jewellery-making.

It is important to select the correct set screw size for your specific application. Using an incorrect screw size can lead to structural failures or damage to the material being fastened. Additionally, when working with outdoor applications, it is crucial to consider using materials that are resistant to corrosion, such as stainless steel or coated fasteners.

Frequently asked questions