Stainless Steel Compression Springs 0.4mm Wire 5mm-50mm Long | Small DIY Springs

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Stainless Steel Compression Springs 0.4mm Wire 5mm-50mm Long | Small DIY Springs

Name: Stainless Steel Compression Springs 0.4mm Wire 5mm-50mm Long | Small DIY Springs
Brand: HomeDIYer
Price: 3.52 USD
Availability: InStock

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By HomeDIYer®

Wire Diameter: 0.4mm

Outer Diameter: 3mm

Length & Amount(pcs): 5mm & 10

Price:

$3.52 USD

Stock:

In stock (500 units), ready to be shipped

Quantity:

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Stainless Steel Compression Springs — Precision 0.4mm Wire for DIY & Mechanical Projects

Finding a reliable small compression spring that won't corrode, fatigue, or lose tension after repeated cycling is a real challenge for makers, engineers, and hobbyists alike. These stainless steel compression springs are engineered for exactly that — delivering consistent return force in compact assemblies where failure is not an option.

Each spring is formed from 0.4mm stainless steel wire with outer diameters ranging from 3mm to 12mm (0.12" to 0.47") and free lengths from 5mm to 100mm (0.20" to 3.94"). The coil geometry provides a linear spring rate suitable for light-load applications, and the stainless steel construction resists oxidation in both indoor and mildly humid environments.

Typical use cases include small compression springs for electronics enclosures and battery contacts, miniature return springs for robotics actuators and servo linkages, and precision coil springs for pen mechanisms, valve assemblies, and DIY jigs requiring repeatable preload.

⚙️ Compatibility: Suitable for spring-loaded mechanisms, battery contacts, push-button assemblies, robotics, and light-duty industrial fixtures requiring OD 3–12mm and free length 5–100mm.

✅ Key Features of These Stainless Steel Compression Springs

🔩

0.4mm Precision Wire Diameter

Consistent wire gauge across all variants ensures predictable spring rate and deflection behavior for repeatable mechanical performance.

📐

Wide Size Range — OD 3mm to 12mm

Nine outer diameter options (3, 4, 5, 6, 7, 8, 9, 10, 12mm) and free lengths from 5mm to 100mm cover the majority of small-mechanism spring requirements.

🛡️

Stainless Steel Construction

Corrosion-resistant alloy maintains spring properties in humid, indoor, and light-exposure environments without surface treatment degradation.

📦

Flexible Pack Quantities

Available in packs of 5, 10, 50, or 100 pieces — order prototyping quantities or bulk stock without overpaying for unused inventory.

⚡

Linear Spring Rate

Uniform coil pitch delivers a consistent, linear force-deflection curve — ideal for applications requiring predictable preload or return force.

🔄

Fatigue-Resistant Coil Geometry

Cold-wound coil construction minimizes stress concentrations, supporting repeated compression cycles in battery contacts, push buttons, and actuator return mechanisms.

📐 Technical Specifications — Compression Spring

Wire Diameter	0.4mm
Outer Diameter (OD)	3mm / 4mm / 5mm / 6mm / 7mm / 8mm / 9mm / 10mm / 12mm (see variant options)
Free Length	5mm – 100mm (see variant options)
Material	Stainless Steel
Spring Type	Compression
Coil Direction	Right-hand wound (standard)
End Type	Closed ends (typically ground or plain — see variant options)
Spring Rate	See variant options
Pack Quantity	5 / 10 / 50 / 100 pcs (see variant options)
Surface Finish	Natural stainless (no coating)

❓ Frequently Asked Questions

How do I choose the right outer diameter and length for my application?

Measure the bore or housing your spring will sit in — the spring OD should be 0.1–0.3mm smaller than the bore for a sliding fit. For free length, choose a spring that is 20–30% longer than your required compressed length to ensure adequate preload without bottoming out. Use the variant selector above to match OD (3–12mm) and free length (5–100mm) to your design.

What load can a 0.4mm wire compression spring handle?

A 0.4mm wire spring is designed for light-duty applications — typically in the range of 0.05N to 2N depending on OD, free length, and deflection. These springs are well-suited for battery contacts, push buttons, pen mechanisms, and small actuator returns. For heavier loads, a larger wire diameter is recommended.

Are these springs corrosion-resistant for outdoor or humid environments?

Yes. Stainless steel provides good corrosion resistance for indoor, mildly humid, and light-exposure outdoor environments. For aggressive chemical or saltwater environments, additional protection or a higher-grade alloy may be required. Contact us to confirm suitability for your specific conditions.

Are these compatible with standard spring housings and plunger assemblies?

Yes — the standardized OD options (3–12mm) are compatible with most commercial spring housings, plunger bores, and off-the-shelf spring guides. Verify the bore diameter and shaft diameter against the selected OD and inner diameter (ID ≈ OD − 2 × wire diameter = OD − 0.8mm) before ordering.

How many pieces should I order for prototyping vs. production?

For prototyping and design validation, the 10-piece pack is ideal — it gives you enough to test multiple configurations without excess stock. For small-batch production runs, the 50-piece pack offers a better per-unit cost. The 100-piece pack is recommended for ongoing production or when stocking multiple size variants.

Can I use these springs in robotics and automation projects?

Absolutely. These small compression springs are widely used in robotics for gripper return mechanisms, servo linkage preload, limit switch actuation, and sensor probe return. The consistent spring rate and stainless construction make them reliable in repeated-cycle automation environments.

What is the inner diameter (ID) of these springs?

The inner diameter is approximately OD − 2 × wire diameter. For example, a 6mm OD spring has an ID of approximately 5.2mm (6mm − 0.8mm). This determines the maximum shaft or guide rod diameter the spring can slide over. Refer to the variant options for exact OD, then calculate ID accordingly.

🛒 Select your Outer Diameter and Length & Amount above, then add to cart.