A Guide to Identifying Fasteners for Replacements and Additional Orders

When you’re working on a project and run out of fasteners or need replacements, it’s essential to order the right ones. With so many different types of fasteners available, identifying the exact screw, bolt, or fixing you need can seem like a daunting task. However, with a few simple steps, and some fastenings terminology under your belt, you can identify what you need and order it with more confidence.

In this guide, we’ll walk you through how to correctly identify and measure fasteners, including diameter, length, material type, drive, and head type, so that you can make the right choice when ordering replacements or additional fasteners.

Step 1: Identify the Fastener Type

The first step is determining the type of fastener you’re dealing with. Common types include:

Woodscrews – Typically threaded along the shank and used to fasten wood materials together by driving into them.

Bolts – Bolts are partially threaded along the shank and Hex Sets also known as Set Screws are fully threaded. Both can be described as bolts. Hex Sets and Bolts can be used with a nut to hold materials together and fastened into a pre tapped hole.

Nails – Are hammered into materials either with a hammer or nail gun.

Once you’ve identified whether it’s a screw, bolt, or another type of fastener, you can move on to the specifics.

Step 2: Measure the Thread Diameter

The thread diameter (also known as the gauge for screws) is a key measurement when identifying fasteners. Here’s how to measure it:

For screws and bolts: Use a vernier to measure the outside diameter of the threads.

– If you don’t have a vernier, you can use a thread gauge or bring the fastener to a fastenings expert for help.

– For screws, the diameter is often given in millimeters (e.g. 5mm) or as a gauge size (e.g. No.8).

Step 3: Measure the Length

The length of a fastener is measured differently depending on the type of fastener:

For screws and bolts: Measure from the underside of the head to the tip of the fastener.

– If the head is countersunk (flat with the surface), measure the entire length of the fastener, including the head.

– For fasteners with a raised head (e.g. pan head, hex head), measure only the shank length, excluding the head.

This measurement is typically given in millimeters or inches – Metric (mm) or Imperial (Inches) (BA, BSW, UNF, UNC)

Step 4: Identify the Material

Fasteners are made from various materials, each with different properties. Common materials include:

Steel – The most common fastener material, often zinc-plated to resist corrosion which gives the fastening a shiny, bright

Stainless Steel – Highly resistant to rust and corrosion, ideal for outdoor or damp environments.

Brass – Corrosion-resistant and used in decorative or electrical applications.

Look closely at the finish of your fastener, as many steel fasteners are coated with zinc or other materials to improve corrosion resistance. Stainless steel often has a more matte or brushed finish compared to shiny zinc-plated fasteners.

Step 5: Identify the Drive Type

The drive type refers to the shape of the fastener’s head that matches with the tool used to turn it. Common drive types include:

Pozi – A cross-shaped slot for a pozi head driver.

Slotted – A single slot in the head for a flathead screwdriver.

Phillips – A cross-shaped slot for a Phillips head screwdriver.

Torx – A star-shaped recess for a Torx driver, providing better grip and reducing the risk of stripping.

Hex/Socket – A hexagonal recess that works with an Allen key or hex bit.

Check the head carefully to see which tool fits best. Matching the correct drive type ensures you can securely fasten the screw without stripping it.

Step 6: Identify the Head Type

Fasteners come with various head types depending on their intended use. The most common head types include:

Pan – A rounded head with a flat underside, ideal for sheet metal or plastic.

Hex/Hex Flange – A six-sided head that can be tightened with a spanner, commonly used for bolts.

Countersunk – Lies flush with the surface when installed.

Round – Round Head with flat underside – used when a decorative appearance is needed and to ensure no sharp edges.

Flange – A low-profile, rounded head

Each head type serves a different purpose, so make sure the replacement matches your original fastener, both for function and appearance.

Conclusion: Ordering the Right Fasteners

Now that you know how to measure the diameter, length, and identify the material, drive, and head type, you’re ready to confidently order the correct fasteners for your project. Be sure to double-check each measurement and take note of any specific finishes or coatings if you’re working in environments exposed to moisture or harsh conditions.

For any additional help, CBL Fastenings is here to assist! Whether you’re shopping online or visiting our store, our team can guide you to the right fastener for your needs. Happy fastening!