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When a project demands consistent push-back force — whether you're repairing a mechanism, building a custom fixture, or prototyping a device — finding a compression spring in exactly the right diameter and wire gauge can be frustrating. These 40mm long compression springs are designed for makers, engineers, and repair technicians who need a dependable coiled spring with precise dimensional control and material options to match the environment.
Each spring is 40mm in free length, with outer diameters ranging from 8mm to 60mm (approx. 0.31" to 2.36") and wire diameters from 1.4mm to 4mm (approx. 0.055" to 0.157"). Available in spring steel, stainless steel, and nickel-plated finishes, sold in packs of 1, 2, 5, or 10 pieces depending on the variant selected.
Typical use cases include mechanical assemblies requiring axial load resistance, DIY tool and fixture fabrication, electronics enclosure latches and button return mechanisms, and light industrial equipment maintenance — all scenarios where a compact 40mm compression spring with a specific outer diameter is needed.
| Spring Type | Compression (coiled) |
|---|---|
| Free Length | 40 mm (approx. 1.57") |
| Outer Diameter (OD) | 8 mm – 60 mm (approx. 0.31" – 2.36") |
| Wire Diameter | 1.4 mm – 4 mm (approx. 0.055" – 0.157") |
| Material Options | Spring steel / Stainless steel / Nickel plated |
| End Type | See variant options |
| Spring Rate | See variant options |
| Surface Finish | Natural (spring/stainless steel) or Nickel plated |
| Pack Quantity | 1 / 2 / 5 / 10 pcs (varies by variant) |
| Operating Temperature | See variant options |
Measure the bore or seat your spring will sit in. The spring's outer diameter should be slightly smaller than the bore (typically 0.5–1mm clearance) so it can compress freely without binding. If the spring sits over a rod, the inner diameter must be larger than the rod diameter. Check both dimensions before selecting your variant.
Spring steel offers strong elastic properties and is suitable for dry, indoor, or low-humidity environments. Stainless steel provides significantly better corrosion resistance, making it the preferred choice for outdoor, marine, food-processing, or humid environments where rust is a concern. Stainless steel variants are priced slightly higher due to material cost.
Stainless steel variants offer good corrosion resistance for most environments. Nickel-plated variants provide an additional surface barrier against oxidation. Spring steel variants are not inherently corrosion-resistant and should be used in dry conditions or protected with a coating if exposed to moisture.
Thicker wire diameters (e.g., 3mm–4mm) produce stiffer springs with higher spring rates, suitable for heavier loads. Thinner wire diameters (e.g., 1.4mm–1.6mm) produce softer springs for light-duty applications. If you have a specific load and deflection requirement, calculate the required spring rate (k = Load / Deflection) and match it to the appropriate wire and OD combination.
For outdoor or wet environments, select the stainless steel or nickel-plated variants. Spring steel variants are not recommended for prolonged exposure to moisture without additional protective coating, as they may develop surface rust over time.
Each variant listing specifies the pack quantity (1, 2, 5, or 10 pcs). You can add multiple variants to your cart to mix different outer diameters, wire gauges, or materials in a single order. Select the quantity and variant combination that matches your project needs.
Free length is the uncompressed length of the spring — in this case, 40mm. This is the starting point for calculating how much the spring will compress under load (deflection). Ensure your assembly has enough travel space to accommodate the spring at its free length, and that the compressed length does not exceed your minimum clearance.
