Glossary

The SAE Washers prevent imbedding or distortion to the material being clamped. The washers provide a smooth, level protective bearing surface to fasten nuts and bolts. Without washers, the bolts, nuts, and screws can lose their clamping load if they imbed into the clamping material. SAE Washers are used in assemblies that are bolting together soft metals, wood and steel and are designed to be used with Grade 2 and 5 strength levels fasteners.

An SAE Hardened Flat Washer (RC 38-45) is a flat washer made to SAE (Society of Automotive Engineers) standards, specifically designed to provide extra strength and durability. The washer is hardened to a Rockwell hardness range of 38-45 on the C scale (RC 38-45), making it suitable for use in high-stress or heavy-load applications.

A common strength classification for carbon steel fasteners made from low-carbon steel. SAE J429 Grade 1 fasteners provide the lowest strength level within the SAE J429 standard and are typically used in light-duty, non-critical applications where only minimal strength is needed. Common uses include furniture assembly, light-duty brackets, automotive trim, electrical enclosures, and other non-load-bearing or temporary connections not subject to high stress or vibration. 

A common strength classification for carbon steel fasteners that are made from low to medium carbon steel. SAE Grade 2 fasteners offer a basic level of strength and are typically used in non-critical, general-purpose applications where high strength is not required.

A common strength classification for carbon steel fasteners made from medium carbon steel that are typically quenched and tempered. SAE J429 Grade 4 fasteners provide a moderate strength level under the SAE J429 standard and are commonly used in applications requiring greater strength than Grade 2 but not as high as Grade 5. These fasteners are suitable for general-purpose mechanical and structural applications where improved load capacity is needed. Common uses include automotive components, machinery parts, and light structural assemblies.

A strength classification for medium carbon steel fasteners that have undergone heat treatment to enhance their strength and durability. SAE Grade 5 fasteners provide greater strength than Grade 2 and are commonly used in automotive, industrial, and structural applications where higher load-bearing capacity is required.

A strength classification for alloy steel fasteners that are typically quenched and tempered, conforming to the SAE J429 standard. Grade 5.1 fasteners provide a higher strength level than Grade 5 and are intended for applications requiring enhanced mechanical performance and durability. Common uses include automotive, heavy machinery, and structural applications where improved toughness and tensile strength are necessary.

A strength classification for alloy steel fasteners that are typically quenched and tempered, conforming to the SAE J429 standard. Grade 5.2 fasteners offer a higher strength level than Grade 5.1 and are used in demanding applications requiring superior mechanical performance and durability. Common uses include heavy-duty automotive, industrial machinery, and structural applications where maximum toughness and tensile strength are critical.

A strength classification for alloy steel fasteners that have been heat treated to provide high tensile strength and excellent durability. SAE Grade 8 fasteners are stronger than Grade 5 and are commonly used in heavy-duty automotive, industrial, and structural applications requiring maximum load capacity and toughness.

A strength classification for alloy steel fasteners that are quenched and tempered, conforming to the SAE J429 standard. Grade 8.1 fasteners provide higher tensile strength and improved toughness compared to Grade 8, making them suitable for high-stress, heavy-duty applications. Typical uses include automotive suspension components, heavy machinery, and structural assemblies requiring superior strength.

A strength classification for alloy steel fasteners, quenched and tempered to exceed the mechanical properties of Grade 8.1 under the SAE J429 standard. Grade 8.2 fasteners are designed for extremely demanding applications where maximum strength, durability, and resistance to fatigue are required. Common applications include critical heavy machinery parts, high-performance automotive, and structural components subjected to intense stress.

A classification under the SAE J995 standard for inch-series hex nuts made from low-carbon steel. Grade 2 nuts are intended for use in light-duty, non-critical applications and are typically paired with SAE J429 Grade 1 or Grade 2 bolts. They offer low mechanical strength and usually lack grade markings.

A classification under the SAE J995 standard for inch-series hex nuts made from medium carbon steel, quenched and tempered. Grade 5 nuts are intended for medium-strength applications and are typically used with SAE J429 Grade 5 bolts. They offer greater mechanical strength than Grade 2 nuts and are identified by two circumferential grade markings located 120 degrees apart, typically with one mark on the top face and the other wrapping partially around the side of the nut.

A classification under the SAE J995 standard for inch-series hex nuts made from medium carbon alloy steel, quenched and tempered. Grade 8 nuts are used in high-strength applications and are typically paired with SAE J429 Grade 8 bolts. They provide the highest strength among SAE J995 grades and are identified by two circumferential grade markings located 60 degrees apart, both positioned clearly on the top face of the nut.

An SAE NT Hardened Flat Washer (RC 38-45) is a hardened flat washer made to SAE (Society of Automotive Engineers) standards, specifically designed to withstand high loads and stress in demanding applications. The washer is hardened to a Rockwell hardness of 38-45 on the C scale (RC 38-45), indicating its high strength and resistance to wear. The "NT" in the name stands for "Narrow Thickness", meaning it has a thinner profile compared to standard hardened washers.

An SAE NT2 Hardened Thick Flat Washer (RC 38-45) is a type of hardened flat washer designed to meet SAE (Society of Automotive Engineers) standards with added thickness. The "NT2" indicates a thicker profile compared to standard washers, while the RC 38-45 refers to the washer's Rockwell C hardness rating, meaning it is heat-treated for enhanced strength and durability.

An SAE NTX Hardened Extra Thick Flat Washer (RC 38-45) is a specialized type of flat washer designed to meet SAE (Society of Automotive Engineers) standards, with an extra thick profile for added durability and support. The washer is hardened to a Rockwell hardness of 38-45 (RC 38-45), providing high strength, wear resistance, and the ability to withstand heavy loads and stress.

This laboratory procedure is designed to quickly assess how well fasteners, materials, or their protective finishes withstand corrosion. Within a sealed chamber, these fasteners are exposed to a controlled, corrosive environment. A fine mist or a fog of salt water (typically a 5% sodium chloride solution) is continuously sprayed onto the items at a consistent temperature. This process mimics and accelerates the effects of harsh environmental conditions, allowing manufacturers to determine how resistant a fastener or its protective finish is to rusting and other forms of deterioration over time. The results from these tests are key for quality control, choosing the right materials, and comparing how different protective coatings perform.

A sandwich-panel screw is a fastener specifically designed to secure lightweight composite panels, which are built from two strong face sheets bonded to a soft or hollow core such as honeycomb, foam, or balsa. Standard screws can easily crush or strip these materials, so sandwich-panel screws use wide threads, collars, or captive washers to spread out the load and prevent damage.

They are commonly found in aerospace, automotive, marine, and construction industries, where lightweight yet strong materials are critical. Some versions feature self-drilling tips for clean penetration of the face sheet, while others include built-in spacers or bushings to avoid over-tightening. This makes them essential for safely fastening panels in aircraft interiors, vehicle bodies, marine decks, and insulated building systems.

A screw is a heavy-duty fastener designed to join materials together by creating its own threads within a material or fitting into a pre-threaded hole. Industrial screws are used in applications such as construction, manufacturing, machinery, and automotive industries, where strong and reliable fastening is required.

A screw eye bolt is a fastener with a looped head and a threaded shaft, commonly used to anchor cables, ropes, or chains into wood. It's often used in light-duty applications like hanging items or guiding wires.

A screw-in anchor is a fastener that creates a secure point in drywall or similar materials for holding screws. It has sharp threads that cut into the material as it’s driven in, providing a strong grip for hanging items like shelves, pictures, or light fixtures.

A pre-applied material on a fastener’s threads that creates a seal to prevent fluid or gas leakage when installed. Unlike locking patches, which focus on preventing loosening, sealing patches are designed to fill gaps between mating threads, providing both a chemical and mechanical seal. They are often used in applications where pressure containment or environmental protection is critical.

Longitudinal surface discontinuities or defects found on fasteners. These imperfections typically originate from flaws in the raw material (such as the wire or bar stock) or are introduced during early manufacturing stages like rolling or drawing. Seams generally appear as straight or slightly irregular lines running along the length of the fastener, commonly located on the shank, under the head, or extending into the threads. They are a significant concern because they can act as stress concentrators, reducing the fastener's fatigue life and serving as initiation points for cracks and eventual failure.

A process used to modify or enhance a fastener after its initial manufacturing. Common secondary operations include drilling, tapping, slotting, shaving, or adding grooves. These steps are necessary when standard cold forming can’t achieve the required detail or precision.

A security spline lug nut is a specialized wheel fastener designed to help prevent wheel theft while also offering a compact profile for tight clearance applications.

Instead of the common hex-shaped head, these lug nuts feature narrow grooves (splines) machined around their exterior. A matching “spline drive” socket is required to install or remove them. Because standard sockets won’t grip the splines, it makes them more secure against theft than conventional lug nuts. The splined design also allows for a smaller outside diameter, which is especially useful on wheels with small lug recesses where a standard hex nut would not fit.

You’ll find security spline lug nuts most often in the automotive aftermarket—on custom alloy wheels, tuner cars, or performance vehicles—where both theft deterrence and aesthetics matter. They provide the dual benefit of locking-style security and a sleek, low-profile appearance.

Self-Drilling Screws are versatile fasteners used to attach different materials together, such as metal to metal, metal to wood, and plastic. These screws have a pointed drill bit that allows them to create their own thread without the need for a pre-drilled pilot hole. This feature makes these screws more versatile compared to traditional screws, as they have the ability to tap, similar to self-tapping screws. As a result, Self-Drilling Screws are suitable for use with a wide range of materials across various industries.

A SEMS screw (or SEMS fastener) is a screw that comes pre-assembled with a captive washer or set of washers during manufacturing. The washer is permanently held in place, typically by rolling the screw threads after the washer is added, which traps it on the shank without preventing rotation. This creates a one-piece fastener that cannot lose its washer, making assembly faster, simpler, and more consistent.

The construction of SEMS screws allows for a variety of configurations. The most common design includes one or two washers—such as flat, lock, or conical washers—positioned beneath the head. These screws can feature different head styles, such as pan heads, hex heads, or Phillips, slotted, or Torx drives. They are also manufactured with various thread types, from machine screw threads to self-tapping versions, depending on the intended application.

The advantages of SEMS screws are clear. They save time by eliminating the need to handle washers separately and prevent washers from being lost during assembly or maintenance. By supplying the washer already in place, they guarantee the correct type is always used, reducing assembly errors. When equipped with lock washers or conical washers, SEMS screws also provide resistance to loosening caused by vibration. Overall, they offer a cost-effective solution in high-volume production environments by cutting down on labor and handling.

Because of these qualities, SEMS screws are used widely across industries. In the automotive industry, they are essential for both interior and engine applications where assembly speed and vibration resistance are critical. In electronics, they secure components in tight spaces where reliability and speed are necessary. In appliances and machinery, they ensure repeatable, dependable fastening for parts that require regular maintenance. They are also used in construction and general manufacturing for efficient, secure joints.

There are also variations of SEMS screws to suit different needs. A common configuration combines a flat washer with a lock washer to provide both load distribution and vibration resistance. Some versions use a tooth lock washer for extra grip in high-vibration conditions. Others feature multiple washers stacked together to deliver a combination of benefits. This versatility makes SEMS screws a highly adaptable and reliable choice in modern fastening applications.

A serrated flange bolt is a hex-head bolt with a built-in washer-like flange under the head. The flange has serrations (ridges) that grip the surface to prevent the bolt from loosening due to vibration. It's commonly used in automotive and machinery applications where secure fastening is critical.

A sex bolt, also commonly known as a barrel nut, Chicago screw, or binding post screw, is a two-part fastener designed to join materials securely while providing a neat, flush appearance on both sides.

A shakeproof washer is a type of lock washer designed to stop fasteners from loosening under vibration or movement. Unlike flat washers that only distribute load, shakeproof washers have serrated teeth—either on the inside edge (internal-tooth) or around the outside edge (external-tooth)—that bite into the fastener and the surface material. This added friction helps resist rotation and keeps the joint secure.

They are commonly used in automotive, electrical, and machinery applications where vibration is a concern. While effective, they can mark softer surfaces and aren’t always the best choice for high-strength structural joints, where more advanced locking solutions may be required.

A carriage bolt, also known as a shaker screen bolt, is a fastener featuring a rounded, dome-shaped head and a square neck directly beneath it, designed to fit into a corresponding square hole or embed into wood or metal to prevent rotation during tightening. These bolts are typically used with a nut and washer to secure materials together. The smooth, rounded head provides a clean, tamper-resistant finish while the square neck locks the bolt in place as torque is applied. Commonly used in wood-to-metal connections, shaker screens, agricultural equipment, and structural assemblies, these bolts are valued for their strength, vibration resistance, and ability to maintain a secure, flush appearance.

The diameter of the unthreaded, cylindrical portion of a bolt or screw. This precise measurement is typically slightly smaller than the major diameter of the threaded portion. This smaller size provides necessary clearance, enabling the fastener to pass through pre-drilled holes smoothly and aiding in proper alignment before the threads engage, ensuring a proper fit within the assembly.

A shear nut is a type of security fastener designed to prevent tampering or unauthorized removal. It consists of a hexagonal upper section used for tightening and a smooth, conical lower section. During installation, the hex portion breaks off (shears) once a specified torque is reached, leaving behind only the tamper-resistant cone.

Because the remaining section has no grip points for standard tools, shear nuts are extremely difficult to remove without specialized equipment. They are commonly used in security-sensitive applications such as fencing, street signs, utility installations, and other public infrastructure where theft or vandalism is a concern.

A shear screw is a tamper-resistant fastener specifically designed so that its drive head intentionally breaks off, or “shears,” when tightened to a predetermined torque. Once this happens, the drive portion separates from the body of the screw, leaving behind a smooth, often conical or headless surface. Because there is no usable drive left, the fastener cannot be engaged with standard tools, making it extremely difficult to remove.

The main purpose of a shear screw is to create a permanent and secure fastening in situations where tampering or unauthorized removal must be prevented. By eliminating the head after installation, the screw ensures that it cannot be loosened without specialized methods such as drilling or destructive extraction, which adds a strong layer of security.

Shear screws are widely used in applications that demand high security and reliability. They are commonly found in access panels, electrical enclosures, and public fixtures, where tampering could compromise safety or operations. They are also used as theft-prevention fasteners in items such as meter housings, street furniture, and alarm systems. Additionally, they serve an important role in safety-critical assemblies where loosening could lead to hazards or failures.

While they share similarities with break-off screws, the defining characteristic of a shear screw is that the head shears away at a calibrated torque, leaving behind a permanent, tamper-proof fixing that is non-removable under normal conditions. This ensures that once installed, the fastener provides long-term security and reliability.

The highest level of stress a fastener can withstand before it fails or fractures when subjected to forces that are applied perpendicular to its axis, tending to slide or slice the fastener apart. Shear Strength is crucial for joints where fasteners resist sideways (lateral) loads, such as in structural connections where components might try to slide past each other.

Sheet metal screws are versatile fasteners designed for securing metal, plastic, and other thin materials. They feature sharp, self-tapping threads that cut into material, creating a secure hold without the need for pre-drilled holes in some applications. Earnest Machine offers Type A, Type AB, and Type B sheet metal screws in various head styles to suit different fastening needs.

A shock absorber nut is a specialized fastener used to secure a vehicle’s shock absorber to its mounting points, typically at the chassis and suspension. It is designed to withstand the high levels of vibration, impact, and dynamic forces that occur as the suspension absorbs shocks from the road. These nuts are often paired with bolts or threaded studs that pass through the shock absorber’s bushings or mounting eyes.

From a design standpoint, shock absorber nuts are usually made from high-strength steel or alloy steel to handle repeated stress cycles. They are often plated with zinc, phosphate, or other coatings to resist corrosion from moisture, road salts, and debris. Many are also designed with locking features—such as nylon inserts (nyloc nuts), distorted threads, or prevailing torque mechanisms—to prevent loosening under constant vibration and movement.

The purpose and function of a shock absorber nut is to maintain a secure, rigid connection between the shock absorber and the suspension or chassis. If the nut loosens, the shock absorber cannot effectively dampen vibrations and impacts, which compromises vehicle stability, safety, and ride comfort. The locking design ensures that preload is maintained over time, even in harsh driving conditions.

In terms of applications, these nuts are used in virtually all types of vehicles—cars, trucks, motorcycles, and heavy equipment. They are critical in suspension systems where reliability under repeated stress is essential.

The advantages of shock absorber nuts are their ability to maintain a secure connection despite constant vibration, their contribution to ride safety and handling, and their corrosion resistance in outdoor environments.

The limitations are that they can be more difficult to remove due to their locking features, may require replacement after disassembly (especially nylon-insert or prevailing torque types), and are application-specific, meaning they need to be matched carefully to the vehicle’s design and shock absorber size.

Short Neck Carriage Bolts feature a shorter, shallower square neck under the rounded head, making them suitable for use with thinner materials like sheet metal. This design prevents damage to the installation surface or connecting material. Due to their versatility, Short Neck Carriage Bolts are commonly used in the assembly of construction equipment, heavy machinery, and furniture where both aesthetics and functionality are important.

Shot peening is a cold working process that strengthens metal parts by bombarding their surface with small, spherical media such as steel, glass, or ceramic balls. This process introduces a layer of beneficial compressive stress on the metal's surface, which significantly improves its resistance to fatigue and cracking.

The process works by using a controlled stream of media to repeatedly strike the metal part. Each impact creates a small dimple, and the plastic deformation of the outer layer creates a compressive stress as it is constrained by the underlying material. This compressive layer is crucial because cracks typically form in areas of tensile stress. By counteracting these stresses, shot peening increases the part's resistance to stress corrosion cracking and fretting, thereby extending its fatigue life.

Shot peening is a vital process in industries where component durability and reliability are essential, including aerospace, automotive, and heavy manufacturing. It's commonly used on parts like turbine blades, crankshafts, and gears to ensure they can withstand high-stress environments and meet rigorous quality and safety standards.

A shoulder bolt, also called a shoulder screw, is a type of fastener with a smooth, unthreaded cylindrical section (the "shoulder") between the head and the threaded end. The shoulder acts as a precise guide or pivot point, making it ideal for applications involving moving parts, alignment, or spacing. These bolts are commonly used in machinery, tooling, and automotive assemblies.

A shoulder nut is a type of nut that has an extended, unthreaded cylindrical section (the "shoulder") below the main hex or square body. This shoulder helps locate or align the nut in an assembly, or acts as a spacer or bearing surface.

Silicon carbide (SiC) is a compound of silicon and carbon that is recognized for its exceptional hardness, thermal stability, and chemical resistance. While it occurs naturally in extremely rare mineral forms such as moissanite, it is primarily produced synthetically and has become one of the most important advanced ceramics in modern industry. Its unique combination of properties allows it to be used both as a high-performance structural material and as a semiconductor in power electronics.

Silicon carbide’s strength comes from its crystalline structure, in which silicon and carbon atoms alternate in strong covalent bonds. This gives it a hardness of about 9–9.5 on the Mohs scale, placing it just below diamond and cubic boron nitride. Unlike many ceramics, it also has high thermal conductivity, which allows it to transfer heat efficiently. SiC can withstand temperatures above 1,600 °C (2,912 °F) without losing strength and is highly resistant to oxidation, corrosion, and chemical attack. In addition, certain forms of SiC function as semiconductors, offering a wide bandgap, high voltage resistance, and efficiency that make them highly valuable in advanced electronics.

The material is typically manufactured through the Acheson process, in which a mixture of silica sand (SiO₂) and carbon, often from petroleum coke, is heated in an electric resistance furnace at temperatures between 2,000–2,500 °C (3,632–4,532 °F). The reaction produces silicon carbide crystals, which can then be ground into abrasive powders, sintered into ceramic components, or grown into wafers for use in electronics.

Applications of silicon carbide are diverse. Its hardness makes it ideal for abrasives such as grinding wheels, sandpapers, and polishing compounds, as well as cutting tools that must endure high wear. In ceramics and refractories, it is used for furnace linings, kiln shelves, and crucibles that must tolerate high heat. In the electronics sector, silicon carbide is increasingly important as a semiconductor material for high-performance power devices used in electric vehicles, solar inverters, and high-frequency systems. The automotive industry uses SiC in performance brake discs, clutches, and heat exchangers, while its lightweight hardness makes it suitable for armor in protective vests and vehicles.

The advantages of silicon carbide include its extreme hardness and wear resistance, ability to withstand very high operating temperatures, chemical stability, corrosion resistance, and efficiency in conducting both heat and electricity in specialized applications. However, it does have limitations. It is brittle compared to metals and can fracture under sudden impact or shock loads. Production costs, particularly for semiconductor-grade SiC, are relatively high. Additionally, its hardness requires specialized equipment and processes for shaping, machining, and finishing. Despite these challenges, silicon carbide remains an essential material for industries demanding high performance in extreme environments.

A Slotted Flat Countersunk Head Cap Screw is a type of fastener designed to sit flush with or below the surface of the material it is securing, thanks to its flat, countersunk head. It features a slotted drive, meaning it has a single straight cut across the head, which is compatible with a flathead or slotted screwdriver. These screws are commonly used in applications where a smooth surface is required after installation, such as in furniture, machinery, and construction.

Jam Slotted Nuts are half as thick as Slotted Nuts. They are designed for low-clearance rotating applications. The slots’ width and depths are manufactured to provide clearance for full engagement of cotter pins or wires — ensuring maximum resistance to loosening.

Hex Slotted Nuts. Castellated Nuts. Slotted Nuts. Whatever you may call them, the nuts perform well under rotating applications. They can be found used in hold bearings and bushing sleeves in place. The castle turret-like features on the top of these nuts permit a cotter pin to lock the nuts in place and prevent loosening.

A slotted reduced-shank screw is a screw with a straight slotted drive and an unthreaded section under the head that’s turned down smaller than the thread’s major diameter—typically near the root diameter. That reduced, smooth shank lets the top material clear the threads so only the far (bottom) material is threaded.

This design pulls joints tight without thread-jacking, lowers driving torque, and reduces splitting in wood, plastics, or thin sheet. The smooth portion can also aid alignment and place the shear plane on solid shank rather than on threads. You’ll see them in cabinetry, plastics assemblies, light machinery, and stacked sheet-metal joints. They’re also called reduced-diameter shank, relieved shank, or waisted screws (distinct from shoulder screws).

A Snap Safety Pin – Two-Wire (also called a double-wire snap pin or snapper pin) is a quick-release retainer with a solid pin and a spring latch made from two parallel wires. The pin passes through aligned parts and has an annular groove near its end. When you flip the double-wire latch over the tip, it snaps into that groove and prevents the pin from backing out under vibration. The two-wire design provides higher spring force, a sturdier latch, and a bigger grip area than single-wire versions.

To use it, insert the pin through the holes, rotate the latch over the chamfered end, and let it snap into the groove. To remove, pull the loop outward to clear the groove and swing it off, then withdraw the pin. This makes it ideal for applications that need fast, tool-free attachment and removal.

Common uses include trailer hitches and drawbars, jack stands, agricultural and landscaping equipment, and material-handling fixtures—anywhere parts are frequently attached and removed. Pins are typically low-carbon or alloy steel with zinc plating, or 300-series stainless; latches are spring steel (zinc-plated) or stainless. Heads may be button/washer style or small forged heads, and pins come straight or bent, commonly in ¼″ to ⅝″ diameters with various usable lengths.

These pins are meant for convenient retention, not for overhead lifting. Choose a pin diameter that closely fits the hole and always confirm the latch is fully engaged in the groove after installation.

A Socket Head Cap Screw, also known as a Socket Head Bolt, is a high-strength fastener with a cylindrical head that contains a hexagonal (Allen) socket drive in its center. It is designed to be installed using an Allen wrench or hex bit, which makes it ideal for applications where torque must be applied in tight or recessed spaces that cannot accommodate a traditional wrench or socket.

These screws are typically manufactured from alloy steel, stainless steel, or other high-strength materials, giving them greater tensile strength than standard hex bolts of the same size. They are offered in a range of finishes such as black oxide, zinc plating, stainless steel, and specialty coatings, all of which provide added resistance to corrosion or chemicals depending on the application. In terms of threading, smaller diameters are often fully threaded, while larger sizes may be partially threaded in accordance with industry standards and performance requirements.

Socket Head Cap Screws are widely used in machinery assembly, automotive applications, aerospace, robotics, and other engineered products where strength, precision, and compact installation are necessary. They are particularly useful in countersunk or flush applications because their small head profile allows them to sit neatly in place without requiring excess clearance.

The advantages of using Socket Head Cap Screws are considerable. Their high tensile strength makes them more durable and reliable under heavy loads. Their recessed drive style allows installation in compact or recessed areas while also providing better torque transmission and reducing the risk of cam-out compared to slotted or Phillips head fasteners. They also create a clean, streamlined appearance, which is valued in many engineered products.

A solid rivet is a type of mechanical fastener used to permanently join two or more pieces of material together.

A spade-head thumb screw is a hand-tightened machine screw whose head is a single flat “paddle” (the spade) projecting from a short round boss. The spade gives your fingers a broad, low-profile surface to pinch and turn, so you can tighten and release the screw without tools. Compared with a knurled-head thumb screw it offers more leverage; compared with a wing-head it occupies less space and is less likely to snag, which is useful where fasteners sit close together, near panels, or in recessed pockets.

Spade-head thumb screws use standard machine threads (inch UNC/UNF or metric) and install into tapped holes or mate with a nut. Length is measured from under the head to the thread end, and some versions include an unthreaded shoulder or a captive washer to provide a smooth bearing surface on panels. Common materials are zinc-plated steel for general use, stainless steel (A2/A4) for corrosion resistance, and brass or nylon where non-marring or non-sparking characteristics are helpful. Many catalogs follow ASME B18.6.8 for inch-series thumb/wing screws; the spade head is one of the common thumb-screw head forms offered to those proportions.

Like all thumb screws, spade-head versions are intended for tool-free, moderate clamping—think guards, covers, jigs, fixtures, and access panels—rather than high-preload or vibration-critical joints. For better retention, users often add a flat washer, lock washer, nylon-insert nut, or a thread-locking patch, and they choose materials/finishes that suit the environment. In short, a spade-head thumb screw trades the maximum torque of a two-wing head for a compact, sleek tab that’s easy to grip and ideal where clearance is tight.

A Spanner screw, also known as a Snake-Eye screw, is a tamper-resistant fastener distinguished by its head design, which features two small round holes instead of a traditional slot or cross recess. It requires a special spanner driver with two matching pins for installation and removal, making it difficult to manipulate with standard tools.

These screws are commonly used in public fixtures, electronics, and environments prone to vandalism—such as restrooms, elevators, and playground equipment—where extra security is needed. While they deter casual tampering, they are not entirely foolproof since the drivers are commercially available, so they’re best described as tamper-resistant rather than tamper-proof.

A spindle clamp nut is a specialized fastener used to secure cutting tools, grinding wheels, or other rotating components to a spindle in machine tools, grinders, CNC equipment, and similar machinery. It ensures that the tool remains firmly fixed during high-speed operation while still allowing for relatively quick installation and removal when tools need to be changed.

In terms of design and construction, a spindle clamp nut is typically circular with a threaded inner bore that matches the spindle threads. The exterior of the nut is shaped with spanner wrench slots, flats, or other gripping profiles so that it can be tightened or loosened with the proper tool. Many designs also feature a clamping mechanism—such as a split collar, spring-loaded section, or locking feature—that provides additional grip and prevents the nut from backing off under vibration. They are most often made from hardened steel or alloy steel to endure the repeated tightening and stresses of high-speed rotation.

The purpose and function of a spindle clamp nut are centered on securing tooling in place with strength and precision. By clamping the tool holder, wheel, or cutter against the spindle face, the nut ensures that the tool runs true, minimizes vibration, and prevents dangerous loosening. In high-precision applications, clamp nuts are manufactured with tight tolerances and are sometimes balanced to reduce runout, which improves accuracy and surface finish in machining or grinding operations.

Spindle clamp nuts have common applications across various industries. They are used in milling machines and CNC machining centers to secure tool holders and cutters, in grinding machines to fasten grinding wheels, in woodworking and routers to hold bits in place, and in other industrial equipment where rotating tools must be firmly secured. Their reliability makes them critical for both metalworking and woodworking environments.

The advantages of spindle clamp nuts include their ability to provide strong, secure tool retention even at high rotational speeds. They resist loosening under vibration, can be reused many times, and in some designs, enable fast tool changes that improve shop efficiency. Their construction makes them essential for safety, as a loose cutting tool or wheel could cause catastrophic damage or injury.

However, there are also limitations. They must be matched carefully to the spindle thread size and design to ensure proper fit. Many require specific spanner wrenches or other tools for tightening and removal, which adds to the handling process. If installed incorrectly, a spindle clamp nut can cause imbalance or vibration that reduces precision and tool life. Precision clamp nuts, especially those designed for high-speed CNC applications, are also more expensive than standard fastening alternatives.

Flat Head Split Drive Anchors offer easy installation and are used in various building materials, such as concrete, brick, mortar, and cement blocks. This fastener is installed into a pre-drilled hole and driven into place using a hammer. A wedging action is created by the crimped f ins on the working end of the fastener, which engages with the walls of the pre-drilled hole, resulting in a secure bond and f lush mounting. With six popular lengths available, Earnest makes it easy to f ind the size needed for your next project.

A split lock washer, also known as a spring lock washer, is a type of washer designed to prevent a nut or bolt from loosening due to vibration or torque. It achieves this by creating tension between the fastener and the material it's securing.

A split rivet, also known as a bifurcated rivet, is a type of rivet distinguished by its split tail, which forms two "legs". This unique design allows for installation without requiring a pre-drilled hole in many cases, especially when joining softer materials.

A spring bar is a small, spring-loaded metal rod commonly used in watches, jewelry, and some light mechanical assemblies to connect parts that need to be both secure and removable.

In wristwatches, spring bars are the tiny cylindrical bars that attach the watch strap or bracelet to the watch case. Each end of the bar has a spring-loaded pin that retracts when you push it inward with a tool. Once the pressure is released, the pins expand back outward, locking into the lug holes of the watch case. This design allows straps to be swapped quickly while keeping them firmly in place during regular use.

Spring bars are typically made of stainless steel for durability and corrosion resistance. They come in a variety of lengths and thicknesses to match different watches and straps, and some are double-flanged or quick-release for easier handling.

Beyond watches, the same principle can be found in other applications where a secure but removable pivot or connector is needed—using the internal spring to keep the bar in place under tension.

Square Head Bolts have been a staple in the locomotive industry for generations. In addition to aesthetic appeal, the square head provides a wider surface area to distribute clamping loads. Earnest provides bolts in Grades 5 and 8 for durability and strength. Get modern strength with a classic look.

A square washer, also known as a square plate washer or construction square plate washer, is a flat washer with a square or rectangular shape. Unlike the more common round washers, square washers offer distinct advantages in specific applications, particularly in heavy-duty and structural contexts.

A manufacturing process that shapes or cuts metal by pressing it with a die. In fastener production, stamping is used to create features like heads, slots, or markings quickly and precisely from sheet metal or wire.

The measure of how much force a fastener can withstand before it begins to deform or break. In fasteners, strength level indicates how well the material performs under load and stress. It is usually defined by standardized properties such as tensile strength and yield strength.

Threads on a fastener or inside a hole that have been damaged, worn down, or torn away, preventing proper engagement. Stripped threads cause loose or insecure fastening, reducing the strength and reliability of the connection.

A structural bolt is a specialized type of bolt designed for use in structural applications, primarily in steel-to-steel connections in buildings, bridges, and other structures where safety and load-bearing capacity are critical.

A stud is a type of fastener that consists of a long, threaded rod used to securely join two or more components in construction, manufacturing, and heavy machinery applications. Unlike bolts, industrial studs typically do not have a head and are secured using nuts on both ends or by threading into a tapped hole.

Superfinishing is a precision surface finishing process used to improve the smoothness, accuracy, and performance of metal parts beyond what conventional grinding or polishing can achieve. It involves the use of fine abrasive stones or tapes that lightly rub against the workpiece under controlled pressure while the part is oscillated or rotated. This removes only a very thin layer of material—measured in microns—but it eliminates surface irregularities, reduces roughness, and creates a highly refined finish.

The key benefit of superfinishing is that it produces surfaces with extremely low roughness and high dimensional accuracy. Unlike standard polishing, which can leave directional scratches or waviness, superfinishing produces a uniform crosshatch pattern that helps retain lubrication on the surface. This makes it especially useful in components subject to friction, wear, or rolling contact.

Common applications include engine components such as crankshafts, camshafts, gears, and bearings, as well as aerospace and precision tool parts. Superfinished surfaces reduce friction and heat buildup, extend component life, improve load-bearing capacity, and enhance fatigue resistance.

In the context of fasteners and mechanical assemblies, superfinishing may be applied to high-performance bolts, shafts, or washers where smooth, uniform surfaces are critical for reducing wear, improving fatigue strength, or preventing premature failure under high loads.

Irregularities or imperfections found on the surface of a fastener that may affect its performance or appearance. These can include cracks, seams, laps, folds, pits, or scratches and are typically caused by issues during forming, machining, or handling. Surface discontinuities are evaluated against industry standards to determine if they are acceptable or if they compromise the integrity of the part.