M3 x 40mm Button Head Allen Stainless Steel Bolt (304) 🔩

The M3 x 40mm Button Head Allen Stainless Steel Bolt (304) is a premium-grade fastener designed for strength, precision, and a professional finish. Made from 304 (A2) stainless steel, it provides excellent corrosion resistance and durability, making it ideal for electronics, industrial equipment, DIY projects, and robotics assemblies. Its low-profile button head and hex (Allen) drive ensure clean, secure, and aesthetic installations in both mechanical and electronic applications.

🧰 Key Features

• Precision metric size: M3 thread x 40mm length
• Button head design: smooth, low-profile finish for a neat appearance
• Hex socket (Allen) drive: ensures reliable torque and easy tightening
• Material: 304 stainless steel for long-term corrosion resistance
• Finish: clean, polished look suitable for exposed or visible assemblies

🛡️ Why 304 Stainless Steel?

Constructed from 304 grade (A2) stainless steel, this bolt delivers superior resistance to oxidation, moisture, and environmental wear. It maintains a consistent finish even in humid or industrial settings, ensuring reliability in both structural and precision applications. The 304 alloy offers an ideal balance between strength and corrosion resistance—making it the preferred choice for electronics modules, machinery, and DIY projects.

⚙️ Typical Applications

• Mounting Raspberry Pi boards (M3 mounting holes) and electronics modules
• Arduino and microcontroller project assemblies
• PCB standoffs and electronics enclosures
• Industrial machinery and equipment assemblies
• Automotive, furniture, or decorative builds where finish matters

Button head bolts are often chosen for their aesthetic appeal while ensuring reliable mechanical strength.

📐 Technical Specifications

• Thread size: M3 (metric)
• Length: 40mm (measured under the head)
• Thread pitch: 0.45mm (standard M3 coarse)
• Head type: Button head
• Drive type: Hex socket (Allen), 2.0mm hex key typical
• Material: 304 stainless steel (A2)
• Finish: Natural stainless, corrosion-resistant

💡 Notes for Electronics Builders

• Perfect for Raspberry Pi mounting with M3 standoffs—ensure clearance near connectors.
• For Arduino and sensor boards, use proper spacers/washers to avoid PCB contact.
• Avoid overtightening into plastic or thin PCBs—use correct torque for safe installation.
• Compatible with standard M3 nuts, nylon lock nuts, and standoffs.

✅ Conclusion

The M3 x 40mm Button Head Allen Stainless Steel Bolt (304) is a versatile and corrosion-resistant fastener ideal for both industrial and electronics projects. Its combination of strength, clean design, and ease of use makes it the perfect choice for builders, engineers, and hobbyists seeking reliable performance and professional results.