Left-Handed vs Right-Handed Fastener Threads

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Watch>>Left-Handed vs Right-Handed Fastener Threads: Uses and Comparison

Left-Handed and Right-Handed Fastener Threads: Uses and Comparison
Fasteners are the nuts, bolts, screws, and other small components that keep machinery and components together in working order. Many fasteners work through the effective use of threads (left-hand thread and right-hand thread), which allow nuts and bolts to screw together effectively.

But how do threads work? The direction in which workers screw and unscrew fasteners has a lot to do with the applications in which they appear. Additionally, many different types of threads exist to optimize different ways to fasten objects. In this blog, we explore a few of the many different varieties of threads as well as their uses.

Common Uses and Applications of Fastener Threads
Screw threads help with many different applications, such as:

  • Fastening: Screw threads appear on traditional fasteners such as nuts, bolts, and screws, and they also help connect threaded pipes, hoses, caps, and fixtures
  • Gear reduction: Screw threads help with gear reduction by using worm drives
  • Linear object movement: Fastener threads can be used to convert rotary motion to linear motion

Understanding Right-Handed vs. Left-Handed Threads
Thread Terminology and Different Types
Threads are continuous helical ridges on cylindrical fasteners. For parts such as screws, the ridges will be on the exterior, and parts like nuts have ridges inside of their cylindrical bodies.
There are a number of common terms to describe different aspects of threads, which we define below:

  • External threads: Threads that wind around the exterior of a fastener’s shaft
  • Internal thread: Threads that run along the inside of a fastener
  • Axis: Longitudinal lines used to measure the length of the fastener
  • Pitch: The distance between a point on one thread to a point on another thread
  • Major diameter: The largest internal or external thread diameter
  • Minor diameter: The smallest internal or external thread diameter

Fastener Threads: What is a Screw Thread?
Screw threads are sloped helices that spiral down the cylindrical surface of parts like screws and bolts. They’re responsible for converting energy between rotational and linear movement and force. Fasteners with compatible threads can provide tight seals for a wide variety of equipment.

Screw Handedness: Left-Hand Thread and Right-Hand Thread
Screw handedness refers to the direction that a screw’s thread wraps around its shaft. Right-handed threads run clockwise, and left-handed threads run counterclockwise. The origin of a thread’s handedness is rooted in human physiology: Screws with different handedness are ergonomic for people depending on their dominant hands.

Most screws today use right-handed threads, and it’s rare to find a left-handed screw used in any application that doesn’t specifically call for it. However, there are some applications that specifically call for the use of left-handed fasteners.

Uses and Applications of Left-Handed Threads
Left-handed threads are also known as reverse threads. These threads are used in specialized applications in which the application of pressure would force a right-handed screw or bolt to come loose.

Some applications that benefit from the use of left-handed fasteners include:

  • Automotive: Some tires’ bolts are reverse threaded to keep torque from loosening them
  • Heating and plumbing: Pipes are often fitted with both right- and left-handed threads to provide an extra layer of defense from leakage
  • Safety: Gas-supply valves use left-handed threads to differentiate them from the valves that control oxygen


Custom Bolts and Fasteners
Our bolts are used by a broad range of industries requiring assemblies and fastening applications. These threaded fasteners can connect machine parts, mount equipment, and more. As a removable fastener, they also facilitate the regular maintenance and inspections that keep equipment running longer.
National Bolt & Nut Corporation offers both standard and custom bolts and fasteners to meet different grades and specifications. This ensures we can cover the full spectrum of our manufacturing customers' applications, including:

  • Mining
  • Heavy equipment
  • Construction
  • Transportation
  • Automotive
  • Energy and alternative energy 


Watch>>>Fastener Material Selection and Plating Guide
Learn how to choose the best Fastener Material & Finish for your project, what are the different Materials Properties, what is Galvanic Corrosion and more here

Watch>>>Custom Bolts and Fasteners | National Bolt & Nut Corporation
We manufacture standard and custom bolts to meet your specifications. Offering a large variety of fastener, thread, bolt, and screw head types, click here to learn more

National Bolt & Nut, Inc.
National Bolt & Nut, Inc. (NBN) is a Domestic Manufacturer of large diameter custom non-standard fasteners for critical care applications.

NBN supplies Bolts, Nuts, Studs and Washers to the Agricultural, Energy, Heavy Equipment, Mining, Petrochemical, and Rock Crushing industries.

We have provided "blue print specials" since 1996 in all grades of steel and exotic materials.
Our ISO compliant Quality Program challenges NBN to identify ways to best serve ever changing customer needs. All fasteners are manufactured to ASME, ASTM, DIN, ISO and to customers proprietary standard specifications.

NBN guarantees to offer custom quality fasteners at the best price with the fastest industry lead times available.