Why Choose Micro Fasteners?
Micro fasteners are the right choice when the assembly requires a small-diameter threaded fastener and standard #6, #8, or larger screws are too big for the application. They are designed to deliver reliable clamping and thread engagement in tight spaces, thin materials, and precision assemblies where every millimeter of clearance matters.
This category includes micro screws, micro bolts, micro nuts, micro washers, micro pins, micro retaining rings, and micro threaded inserts in both Unified National thread sizes from #0-80 through #4-40 and metric thread sizes from M1 through M3. Available in stainless steel, alloy steel, brass, nylon, and zinc plated steel, with a range of head styles and drive types to match the requirements of the assembly.
Common Uses for Micro Fasteners
Micro fasteners are commonly used in electronics assembly, printed circuit board mounting, optical instrument housings, camera bodies, eyeglass frames, medical device enclosures, robotics, RC vehicles, drone frames, computer hardware, precision instrument panels, and small mechanical assemblies.
They are also used for repair and maintenance of small consumer products, lab equipment, and any assembly where the fastener must fit into a confined space or thread into a small boss, insert, or tapped hole.
Micro Fastener Thread Sizes
Micro fasteners on this page are available in both Unified National (imperial) and metric thread sizes. Select the thread size based on the tapped hole or threaded insert in the mating part.
Unified National imperial micro thread sizes:
- #0-80 (smallest diameter, 80 threads per inch)
- #1-64 (64 threads per inch)
- #1-72 (72 threads per inch)
- #2-56 (56 threads per inch)
- #2-64 (64 threads per inch)
- #3-48 (48 threads per inch)
- #3-56 (56 threads per inch)
- #4-40 (40 threads per inch)
- #4-48 (48 threads per inch)
Metric micro thread sizes:
- M1 x 0.25 (1mm diameter, 0.25mm pitch)
- M1.2 x 0.25 (1.2mm diameter, 0.25mm pitch)
- M1.4 x 0.3 (1.4mm diameter, 0.3mm pitch)
- M1.6 x 0.35 (1.6mm diameter, 0.35mm pitch)
- M2 x 0.4 (2mm diameter, 0.4mm pitch)
- M2.5 x 0.45 (2.5mm diameter, 0.45mm pitch)
- M3 x 0.5 (3mm diameter, 0.5mm pitch)
For imperial sizes, the first number is the screw diameter designation and the second number is threads per inch. For metric sizes, the M designation is the nominal diameter in millimeters and the pitch is the distance between threads in millimeters. Do not mix imperial and metric fasteners in the same tapped hole. Always confirm the thread standard before ordering.
Imperial vs Metric Micro Fasteners
Imperial micro fasteners use Unified National thread designations (#0-80, #2-56, #4-40, etc.) and are specified in inches. They are the standard in US-designed products, US military and defense equipment, and domestically manufactured assemblies.
Metric micro fasteners use ISO thread designations (M1, M1.6, M2, M3, etc.) and are specified in millimeters. They are the standard in European and Asian-manufactured products, imported consumer electronics, cameras, optical equipment, and internationally designed assemblies.
The two systems are not interchangeable. A metric M2 screw will not thread into a #2-56 tapped hole and vice versa. Identify the thread standard from the original equipment documentation, the existing fastener, or by using a thread gauge before ordering replacements or additions.
Micro Fastener Head Styles
Micro fasteners are available in multiple head styles. Choose based on the required bearing surface, the available drive access, whether the fastener will sit flush or proud of the surface, and the appearance requirements of the finished assembly.
Pan head micro screws provide a low-profile rounded head with a wide bearing surface and are commonly used in electronics and general small assembly. Flat head micro screws are countersunk and sit flush with the surface, useful when a smooth finished appearance is needed. Socket head cap screws provide a cylindrical head with a hex socket drive, commonly specified for precision mechanical assemblies and fixtures. Fillister head micro screws have a taller, narrower head with deep drive slots and are used when extra drive depth is needed in a small-diameter fastener. Button head micro screws offer a low dome profile and are often chosen for aesthetic applications.
Micro Fastener Drive Types
Micro fasteners are available with Phillips, slotted, hex socket (Allen), and Torx drive configurations. Choose the drive type based on the tools available, the torque required, and the access space around the fastener head during installation.
Phillips and slotted drives are common in consumer electronics and general repair. Hex socket drives are frequently used in precision mechanical assemblies and allow higher torque application in a small head. Torx drives provide good resistance to cam-out and are common in medical device and electronics manufacturing.
Micro Fastener Materials
Micro fasteners are available in stainless steel, alloy steel, brass, and nylon. Select the material based on the corrosion environment, the required strength, the electrical conductivity requirements of the assembly, and whether the fastener will be visible in the finished product.
Stainless steel micro fasteners (18-8 and 316) provide good corrosion resistance and are commonly used in medical, optical, marine, and outdoor applications. Alloy steel micro fasteners provide higher tensile strength and are used in mechanical assemblies where load capacity matters. Brass micro fasteners are electrically conductive, non-magnetic, and often chosen for electrical and electronic assemblies. Nylon micro fasteners are non-conductive, lightweight, and used where electrical isolation or resistance to chemicals is needed.
Stainless Steel Micro Fasteners
Stainless steel micro fasteners are available in 18-8 (304) and 316 stainless steel. 18-8 stainless provides good corrosion resistance for most indoor and moderate outdoor environments. 316 stainless provides better resistance to chlorides and salt exposure and is preferred for marine, coastal, and medical applications.
Choose stainless steel micro fasteners when corrosion resistance, appearance, or non-magnetic properties are important to the application.
Brass Micro Fasteners
Brass micro fasteners are electrically conductive, non-magnetic, and naturally resistant to corrosion in many environments. They are commonly used in electrical assemblies, RF and electronic enclosures, optical instruments, and any application where a non-ferrous, conductive fastener is specified.
Brass is a softer material than stainless or alloy steel. Avoid over-torquing brass micro fasteners, especially in very small diameters, to prevent thread stripping or head damage.
Nylon Micro Fasteners
Nylon micro fasteners are non-conductive, lightweight, and resistant to many chemicals and solvents. They are commonly used in circuit board mounting, electrical isolation applications, and assemblies where metal fasteners could cause a short circuit or interfere with sensitive components.
Nylon micro fasteners have lower tensile strength than metal options and are not suitable for applications requiring significant clamping load or exposure to high temperatures.
Micro Fasteners vs Standard Machine Screws
Imperial micro fasteners cover thread sizes #0-80 through #4-40. Standard machine screws typically begin at #4-40 and go up through #6-32, #8-32, #10-24, 1/4-20, and larger. Metric micro fasteners cover M1 through M3. Standard metric machine screws typically begin at M3 and go up through M4, M5, M6, and larger.
Choose micro fasteners when the assembly design, hole size, or boss diameter cannot accommodate a #6 or M4 or larger screw. If a #4-40 or M3 fastener fits the application, compare both micro and standard machine screw options for the best availability and pricing.
Complete Micro Fastener Hardware
Matching micro nuts, micro washers, micro pins, micro retaining rings, and micro threaded inserts are available to complete any small-scale fastener assembly. Hex nuts, nylon insert locknuts, and flat washers in #0-80 through #4-40 and M1 through M3 sizes allow complete threaded fastener assemblies to be built using micro-sized hardware throughout.
Micro dowel pins and cotter pins cover alignment and retention needs on small shafts. Micro external retaining rings in E-style and SE-style configurations retain components on shafts from 1/16" through 1/8". Micro threaded inserts in #4-40 and M3 create durable metal threads in wood and soft material assemblies. Browse the subcategories below to find the right micro hardware for your application.
How to Choose the Right Micro Fastener
Choose the micro fastener based on the thread size and pitch required by the mating hole or insert, the head style and drive type that fits the assembly and installation tool, the material that suits the corrosion environment and strength requirements, and the length needed to achieve proper thread engagement without bottoming out or protruding excessively.
As a general rule, aim for a minimum of 1.5 times the screw diameter in thread engagement for metal assemblies. In very soft materials or thin-walled bosses, consider threaded inserts to improve thread engagement and extend the service life of the tapped hole.
Related Categories
- Micro Screws & Bolts
- Micro Nuts
- Micro Washers
- Micro Pins
- Micro Retaining Rings
- Micro Threaded Inserts
- Machine Screws
- Threaded Inserts
- Shop by Material
- Fastener Assortment Kits
Micro Fastener FAQs
What size are micro fasteners?
Micro fasteners on this page are available in imperial sizes from #0-80 through #4-40 and metric sizes from M1 through M3. These sizes are smaller than standard machine screws and are used in precision, electronic, optical, and medical applications where larger fasteners will not fit the assembly.
What is the difference between #0-80 and #4-40?
#0-80 is the smallest imperial thread size in this category, with a nominal diameter of approximately 0.060" and 80 threads per inch. #4-40 has a larger nominal diameter of approximately 0.112" and 40 threads per inch. Choose the size based on the tapped hole or insert in the mating part.
What is the difference between imperial and metric micro fasteners?
Imperial micro fasteners use Unified National thread designations (#0-80, #2-56, #4-40) and are measured in inches. Metric micro fasteners use ISO thread designations (M1, M2, M3) and are measured in millimeters. The two systems are not interchangeable. Always confirm the thread standard before ordering to ensure compatibility with the tapped hole or mating component.
What materials are micro fasteners available in?
Micro fasteners on this page are available in 18-8 stainless steel, 316 stainless steel, alloy steel, brass, and nylon. Choose based on strength requirements, corrosion environment, conductivity, and appearance.
Can I use micro fasteners in electronics assemblies?
Yes. Micro fasteners are commonly used in electronics assembly for circuit board mounting, enclosure assembly, and component attachment. Choose the material based on conductivity and isolation requirements. Nylon micro fasteners are non-conductive. Brass micro fasteners are conductive. Stainless steel is non-magnetic.
What tools do I need to install micro fasteners?
Micro fasteners require small precision screwdrivers, hex keys, or Torx drivers sized to match the drive type and head size. Use a torque driver when consistent torque is important, especially in medical, aerospace, or precision mechanical applications. Avoid over-torquing, particularly in brass or nylon micro fasteners.
Do you sell micro nuts and washers to match?
Yes. Matching micro nuts and washers are available in the same thread sizes. Browse the related categories above or contact us if you need help locating a specific size or material combination.
What is the minimum order for micro fasteners?
Micro fasteners are available in individual sizes with no minimum order requirement. Bulk pricing is available for large quantity orders. Contact us for pricing on high-volume or recurring micro fastener needs.