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When a project demands reliable spring force over a long stroke, finding the right compression spring in the correct wire diameter and outer diameter can be a real challenge. Whether you are a mechanical engineer specifying components, a hobbyist building a custom mechanism, or a maintenance technician replacing worn-out springs, these 300mm steel compression springs give you the exact combination of wire diameter and outer diameter you need without compromise.
Each spring is formed from steel wire with wire diameters ranging from 0.3 mm to 3 mm (approximately 0.012 in to 0.118 in) and outer diameters spanning 2 mm to 50 mm (approximately 0.08 in to 1.97 in). The free length of each spring is 300 mm (approximately 11.8 in), providing a generous working stroke suitable for a wide range of load and deflection requirements. Variants are sold individually (1 pcs per order) so you can source exactly the quantity you need.
These pressure coil springs are well suited to DIY machinery builds, custom jigs and fixtures, automotive suspension prototyping, robotics and automation assemblies, and general industrial maintenance. Their consistent coil pitch and uniform wire cross-section make them a dependable choice for compression spring replacement projects and new-build mechanical designs alike.
Wire diameters from 0.3 mm to 3 mm paired with outer diameters from 2 mm to 50 mm give you precise control over spring rate and load capacity for your specific application.
A 300 mm (approx. 11.8 in) free length provides a long working stroke, making these springs suitable for mechanisms that require significant travel or high deflection.
Formed from steel wire, these coil springs offer the stiffness and fatigue resistance needed for repeated compression cycles in both light-duty DIY and more demanding mechanical environments.
Uniform coil pitch and wire cross-section throughout the spring body ensure predictable load-deflection behaviour and stable performance across the full compression range.
Suitable for machinery, robotics, automotive prototyping, jigs, fixtures, and general industrial maintenance — wherever a reliable axial compression element is required.
Each variant is available as a single piece (1 pcs), letting you order exactly the quantity you need without committing to bulk packs when only one or a few springs are required.
| Spring Type | Compression (Pressure Coil) |
|---|---|
| Material | Steel wire |
| Free Length | 300 mm (approx. 11.8 in) |
| Wire Diameter | See variant options (0.3 mm – 3 mm) |
| Outer Diameter | See variant options (2 mm – 50 mm) |
| Quantity per Order | 1 pcs |
| Spring Rate | See variant options |
| End Type | Contact us to confirm |
| Surface Finish | Contact us to confirm |
Wire diameter directly affects spring rate and load capacity — a thicker wire produces a stiffer spring. For light-duty mechanisms or small deflections, wire diameters of 0.3 mm to 0.8 mm are typically appropriate. For heavier loads or larger mechanisms, consider 1 mm to 3 mm wire. If you know your required spring rate or load, use standard spring design formulas (or consult an engineer) to confirm the correct wire diameter before ordering.
Wire diameter is the thickness of the steel wire used to wind the coil. Outer diameter is the overall width of the coil spring measured across the outside of the coils. When fitting a spring inside a bore, the outer diameter must be smaller than the bore. When fitting a spring over a rod or shaft, the inner diameter (outer diameter minus twice the wire diameter) must be larger than the rod. Both dimensions are listed in the variant selector.
These springs are made from steel wire. Steel can be susceptible to corrosion if exposed to moisture, salt, or chemicals without protective treatment. For outdoor or corrosive environments, consider applying a rust-inhibiting coating after installation, or contact us to confirm whether a treated or stainless variant is available for your size requirement.
These are compression springs designed to resist and store energy when compressed along their axis. They are not intended for tension (extension) loads. If your application requires a spring that stretches under load, you would need an extension spring instead. For purely axial compression applications — such as return mechanisms, cushioning, or preloading — these springs are well suited.
Spring rate (k) is calculated using the formula k = (G × d⁴) / (8 × D³ × n), where G is the shear modulus of the material, d is the wire diameter, D is the mean coil diameter (outer diameter minus wire diameter), and n is the number of active coils. Because the number of active coils varies by variant, please contact us if you need the spring rate for a specific size combination and we will provide the available specification data.
Maximum safe deflection depends on the wire diameter, outer diameter, and number of coils. As a conservative guideline, compression springs should not be compressed beyond approximately 70–80% of their free length in continuous-duty applications to avoid set (permanent deformation). For a 300 mm free-length spring, this typically means a maximum working deflection of around 210–240 mm, though the exact limit varies by variant. Contact us to confirm the solid height for your specific size.
Cutting a compression spring to a shorter length is possible but will change its spring rate and load characteristics, and the cut end will need to be ground flat for stable seating. If you need a specific free length shorter than 300 mm, it is generally more reliable to select a spring manufactured to that length. Contact us if you need guidance on available lengths.
