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When a machine stalls, a jig loses tension, or a return mechanism fails to reset, the culprit is often an undersized or worn compression spring. Engineers, makers, and maintenance technicians who need a reliable, dimensionally consistent 300mm compression spring will find this range covers the full spectrum of load requirements — from delicate instrument springs to heavy-duty industrial return springs.
Each spring in this series is formed from round steel wire and measures 300mm (11.81 in) in length. Outer diameters span 3mm to 40mm (0.12–1.57 in), and wire diameters range from 0.3mm to 5.0mm (0.012–0.197 in), giving you precise control over spring rate and load capacity. The coil geometry follows standard close-wound compression profiles with flat ground ends on larger sizes (typically OD ≥ 10mm) for stable seating.
Typical use cases include: linear actuator return mechanisms in automation equipment, die and mold ejector pin assemblies requiring consistent 300mm compression spring stroke, custom jig and fixture clamping systems, and hobbyist CNC or 3D-printer Z-axis tensioning where a pressure spring with controlled wire diameter ensures repeatable force output.
Wide Size Range — OD 3–40mm and wire dia 0.3–5.0mm in a single product family, covering light-duty instrument springs through heavy industrial pressure springs.
Fixed 300mm Free Length — Consistent 300mm (11.81 in) free length across all variants simplifies drop-in replacement and standardized fixture design.
Round Wire Construction — Uniform round wire cross-section delivers predictable spring rate and fatigue resistance across repeated compression cycles.
Corrosion-Resistant Finish — Surface treatment (see variant options) helps resist oxidation in workshop and light-industrial environments.
Flexible Pack Quantities — Available in packs of 1, 2, 3, 5, or 10 pieces, so you can order exactly what your project or maintenance stock requires.
Closed & Ground Ends (larger OD) — Flat-ground ends on larger diameter variants provide square seating for stable axial load transfer in precision assemblies.
| Free Length | 300mm (11.81 in) |
|---|---|
| Outer Diameter (OD) | 3mm – 40mm (0.12 – 1.57 in) |
| Wire Diameter | 0.3mm – 5.0mm (0.012 – 0.197 in) |
| Material | See variant options |
| Surface Finish | See variant options |
| End Type | Closed (small OD); Closed & Ground (larger OD, typically ≥ 10mm) |
| Coil Direction | Right-hand wound (standard) |
| Spring Rate | See variant options |
| Load Capacity | See variant options |
| Pack Quantity | 1 / 2 / 3 / 5 / 10 pcs |
| Weight (per piece) | See variant options |
Match the OD to your housing bore or guide rod: the spring OD should be 0.5–1.5mm smaller than the bore ID, or 0.5–1.5mm larger than the guide rod OD. Wire diameter determines spring rate — a thicker wire produces a stiffer spring. For light-duty return or tensioning tasks, wire diameters of 0.3–1.0mm are typical; for heavier loads, select 1.5–5.0mm wire.
Spring rate varies by OD and wire diameter combination. It is not listed as a fixed value because each size variant has a different rate. If you need a specific spring rate (N/mm or lbf/in), please contact us with your OD, wire diameter, and load requirements and we can confirm suitability.
The springs carry a surface treatment that provides moderate corrosion resistance suitable for indoor workshop and light-industrial use. For prolonged exposure to moisture, chemicals, or outdoor conditions, we recommend applying a light machine oil or selecting a stainless steel variant if available. Contact us to confirm material options for your environment.
Smaller OD variants (typically under 10mm) feature closed ends for compact seating. Larger OD variants (typically 10mm and above) feature closed and ground ends, which provide a flat bearing surface for stable axial load transfer — important in precision jigs, molds, and actuator assemblies.
Yes. The 300mm free length and wide OD/wire diameter range make these springs well-suited for Z-axis tensioning on 3D printers, ejector pin return in CNC mold tooling, and linear actuator return mechanisms in automation fixtures. Select the OD and wire diameter that match your guide rod or bore dimensions and your required preload force.
For prototyping or single-machine repair, a pack of 1 or 2 is sufficient. For production fixtures or maintenance stock where springs are replaced periodically, packs of 5 or 10 offer better per-unit value. If you need quantities beyond 10, contact us for bulk pricing.
A compression spring is designed to resist compressive (pushing) forces and returns to its free length when the load is removed. A tension spring, by contrast, resists stretching forces. These 300mm pressure springs are compression type — they are installed between two surfaces and push them apart when compressed.
