Screws Mcmaster Carr

Julian Sterling

-Apr 23, 2026, 1:02 AM

McMaster-Carr offers a wide variety of screws, including set screws, socket head screws, and standard screws. To ensure you select the correct screw for your project, it is essential to understand the different types of screws and their specific measurements. This guide will provide an overview of how to measure screw thread size, choose the appropriate set screw, and select the right socket head screw profile for your needs.

By following these guidelines, you can make informed decisions when working with screws and ensure successful fastening and assembly in your projects. Explore related products Screw thread size The process of measuring screw thread size differs between the metric system and the imperial system. Metric System In the metric system, the screw diameter is given in millimetres and is preceded by the letter "M". For example, M6 corresponds to a diameter of 6mm. The second number indicates the pitch, or the space between threads.

For instance, M6 × 1 mm indicates a coarse pitch, while M6 × 0.75 mm indicates a fine pitch. If the pitch is unknown, it is recommended to choose coarse threads, which are the industry standard. Imperial System In the imperial system, the diameter of screws smaller than 1/4 inch is indicated by a number. For example, "#10" or "No.10" corresponds to a diameter of 0.190 inches and has 24 threads per inch.

The thread spacing, or the number of threads per inch, is represented by the second number in the thread size. General Instructions Regardless of the measurement system, the screw diameter or size is determined by measuring the width of the threaded portion of the screw. This value corresponds to the first number in the thread size.

Screw Sizes for Envy X360 M6 Convertible: A Quick Guide You may want to see also Explore related products $12.95 Screw thread diameter The diameter of a screw thread is an essential measurement when selecting a screw for a project. The diameter corresponds to the first number of the thread size. This measurement is taken by measuring the width of the threaded part of the screw.

For the imperial system, any screw with a diameter smaller than a quarter inch will be indicated by a number, as referenced in a table. For example, 8 corresponds to 0.164 inches. A quarter-inch diameter screw would be indicated as #10 or No.10. A 10-24 screw, for instance, has a 0.190-inch thread diameter. In metric measurements, the diameter is indicated in millimetres and preceded by the letter M. For example, M6 corresponds to 6 mm. Metric thread sizes also specify the pitch, which is the space between threads.

A pitch of M6 x 1 mm is considered coarse, while M6 x 0.75 mm is a fine pitch. If the pitch is unknown, it is recommended to choose coarse threads as they are the industry standard. Standard socket head screws have a head height that matches the screw's thread diameter and are suitable for high-strength fastening. High-profile socket head screws have a head height one and a half times taller than standard, making them useful for deep holes or hard-to-reach areas.

Low-profile and ultra-low-profile screws are used when head space is limited but are not recommended for high-strength fastening. How to Remove Paint from Screw Heads Easily You may want to see also Explore related products Thread spacing For the inch system, thread spacing is determined by counting the number of threads within a one-inch length of the screw. This value is then used as the second number of the thread size. For example, a 10-24 screw has 24 threads per inch.

On the other hand, metric screws measure thread spacing in millimetres. This value directly represents the length between adjacent threads. For instance, a metric screw designated as M6 x 1 mm has a thread spacing of 1 mm. It is important to note that thread spacing is distinct from thread pitch, although both concepts are related to the distance between threads. Thread pitch specifically refers to the distance between adjacent threads within one inch or one millimetre, depending on the measurement system.

In the context of metric thread sizes, a pitch of M6 x 1 mm is considered coarse, while M6 x 0.75 mm is classified as fine. If you are unsure about the pitch, it is generally recommended to opt for coarse threads, which are the industry standard. By understanding the concept of thread spacing and its measurement, you can accurately determine the second number of the thread size for both inch and metric screws.

This information is crucial for selecting or replacing screws, nuts, and other threaded components to ensure compatibility and proper function. Mounting Your UN55NU7100: Screw Size Requirements You may want to see also Explore related products Socket head screws Socket head cap screws, also known as Allen head screws, are a type of fastener with a cylindrical head and a hexagonal recess. They are designed to be used with a hex key or Allen wrench, requiring minimal clearance around the fastener.

The head of a socket head cap screw sits in a recess, eliminating the need for clearance around the head during wrenching. Socket head cap screws are commonly used in industrial production and assembly lines, including automotive, furniture manufacturing, machine tooling and steel fabrication. They provide a secure and efficient fastening solution for a wide range of applications. When selecting socket head cap screws, it is important to consider the material and grade. They are typically made from alloy steel or stainless steel.

Alloy steel socket head cap screws, such as those conforming to ASTM A574, offer high strength and are suitable for applications requiring quenched and tempered alloy steel. On the other hand, stainless steel socket head cap screws, such as those conforming to ASTM F837, provide corrosion resistance and are ideal for applications requiring general corrosion protection. In addition to the screw material, the diameter and thread size are also critical factors in screw selection. Socket head cap screws are available in various diameters, typically ranging from 0.060 to 4.000 inches.

The thread size is specified differently for inch and metric systems. For inch measurements, the screw diameter is denoted by a number or fraction of an inch, while for metric measurements, it is represented by the letter "M" followed by the diameter in millimetres. The Ultimate Guide to Oversized Socket Head Cap Screws You may want to see also Explore related products Set screws There are several types of set screw, each with a different tip that is designed for use with specific materials and surfaces.

Cup The cup set screw has a thin edge that digs into the contact surface to create a secure hold. This type of set screw is suitable for a wide range of surfaces. Knurl-Grip Cup The Knurl-Grip Cup set screw features serrations on the cup edge, which grip the material surface. Flat Flat set screws are designed for use on flat surfaces. The tip of the screw makes good contact with the flat surface to hold objects in place.

Oval Oval set screws are designed for use in U-shaped and V-shaped grooves, as well as other sloped or angled surfaces. Cone The cone set screw has a pointed tip that wedges into soft materials, such as brass. This provides a secure hold. Extended Also known as dog-point set screws, extended set screws feature a protruding tip that locks within a mating hole or slot. This type of set screw is used to keep parts aligned.

Materials Apple Case Screw Sizes: MacBook White Edition You may want to see also Frequently asked questions Measure the width of the threaded part of the screw in millimeters. This number is usually preceded by the letter M (e.g. M6 corresponds to 6 mm). Measure the width of the threaded part of the screw in inches. Any diameter smaller than 1/4" is indicated by a number, which you can reference in a table (e.g. 8 corresponds to 0.164"). Thread spacing refers to the number of threads in a given length.

For inch measurements, this length is always 1 inch. For metric screws, this length is given in millimeters. Pitch refers to the space between threads. For metric screws, if the pitch is unknown, it is recommended to choose coarse threads as they are the industry standard.

Screws Mcmaster Carr

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