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When a mechanism needs consistent return force and your current spring keeps failing under load or losing tension over time, the root cause is usually a mismatch between wire diameter, outer diameter, and free length. These 40mm compression springs are engineered for makers, engineers, and repair technicians who need a dependable coiled spring that holds its rated load cycle after cycle.
Each spring is wound from round wire with a free length of 40mm (approximately 1.57 inches). Wire diameters range from 0.2mm to 1.4mm, and outer diameters span 2mm to 25mm (roughly 0.08–0.98 inches). Available in 304 stainless steel, spring steel, and zinc-plated carbon steel to match your corrosion and load requirements.
Typical use cases include 40mm compression spring for CNC machine tool holders, small-diameter coiled spring for electronics enclosure latches, and pressure spring replacement for 3D printer extruder assemblies and robotics end-effectors.
| Free Length | 40 mm (approx. 1.57 in) |
|---|---|
| Wire Diameter | 0.2 mm – 1.4 mm (see variant options) |
| Outer Diameter | 2 mm – 25 mm (see variant options) |
| Material | 304 Stainless Steel / Spring Steel / Zinc-Plated Carbon Steel (see variant options) |
| End Type | Closed & ground |
| Spring Type | Compression (coiled) |
| Pack Quantity | 5 pcs (Zincification) / 10 pcs (Stainless & Spring Steel) |
| Load Capacity | See variant options |
| Surface Finish | Natural (stainless/spring steel) / Zinc-plated (carbon steel) |
Measure the inner diameter of the bore or housing where the spring will sit. The spring's outer diameter should be 0.5–1mm smaller than the bore to allow free movement without binding. If the spring rides on a guide rod, the inner diameter of the spring (outer diameter minus twice the wire diameter) must clear the rod with at least 0.3mm of play.
Wire diameter directly affects spring rate and maximum load. Thinner wire (0.2–0.4mm) suits low-force applications such as button returns and sensor contacts. Medium wire (0.5–0.8mm) works well for latches, small actuators, and 3D printer components. Heavier wire (0.9–1.4mm) is appropriate for tool holders, industrial fixtures, and higher-cycle fatigue applications. If you need an exact spring rate, contact us to confirm.
304 stainless steel offers the best corrosion resistance among the three options and is suitable for humid environments, light chemical exposure, and food-adjacent applications. Spring steel provides superior fatigue strength but will rust without protective coating in wet conditions. Zinc-plated carbon steel offers moderate corrosion protection for indoor or dry environments at a lower cost.
Yes. The 40mm free length and small outer diameter options (4–8mm) are commonly used in extruder tensioner arms, hotend mounts, and bed-leveling assemblies. Select stainless steel for heat-adjacent placements. Verify the outer diameter and wire diameter against your printer's spring seat dimensions before ordering.
For outdoor or marine use, choose the 304 stainless steel variant. Spring steel and zinc-plated variants are not recommended for prolonged saltwater or high-humidity exposure without additional sealing or coating. For highly corrosive environments, consider 316 stainless steel alternatives or apply a corrosion-inhibiting lubricant.
Spring steel (typically 65Mn or similar) has a higher tensile strength and better fatigue life under repeated compression cycles, making it the preferred choice for high-cycle mechanical applications. Stainless steel (304) trades some fatigue strength for corrosion resistance and is better suited for environments where rust is a concern. For most DIY and light industrial uses, either material performs reliably within the rated deflection range.
Stainless steel and spring steel variants are sold in packs of 10 pieces. The zinc-plated (Zincification) variant is sold in packs of 5 pieces. Pack quantity is shown in the "Material Selection & Qty" option when you select your variant above.
