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When a worn or missing compression spring causes your mechanism to fail — whether it's a jig, fixture, drawer slide, or small appliance — finding the exact wire diameter and outer diameter combination quickly matters. Engineers, hobbyists, and repair technicians who need a reliable 300mm compression spring in a specific size will find this range covers the most commonly required dimensions without custom ordering.
These compression springs are wound from carbon steel wire with a smooth, consistent coil pitch. Wire diameters span 0.3 mm to 2.0 mm (approx. 0.012" to 0.079"), outer diameters range from 2 mm to 35 mm (approx. 0.08" to 1.38"), and all variants share a free length of 300 mm (approx. 11.8"). Each spring is sold individually (except the 21-piece bundle variant) so you can order exactly what you need.
Typical applications include compression spring replacement in electronic enclosures and PCB test fixtures, return-force mechanisms in woodworking jigs and clamps, light-load suspension in scale models and RC vehicles, and valve or plunger return springs in fluid-handling equipment.
| Spring Type | Compression (coil) |
|---|---|
| Free Length | 300 mm (approx. 11.8") — 210 mm for bundle variant |
| Wire Diameter Range | 0.3 mm – 2.0 mm (0.012" – 0.079") |
| Outer Diameter Range | 2 mm – 35 mm (0.08" – 1.38") |
| End Type | Closed, not ground |
| Material | Carbon steel |
| Surface Finish | See variant options |
| Spring Rate | See variant options |
| Load Capacity | See variant options |
| Quantity per Order | 1 pc (21 pcs for bundle variant) |
| Weight | See variant options |
Match three dimensions: outer diameter (OD) to fit inside your bore or housing, wire diameter to achieve the load you need, and free length to suit your travel range. For a 300 mm free length spring, measure the cavity depth and ensure the spring can compress to your required working length without going solid (coil-bound). If you are unsure, select a wire diameter on the lighter end and test before committing to a larger order.
Spring rate (stiffness) increases significantly with wire diameter — a 2.0 mm wire spring is considerably stiffer than a 0.3 mm wire spring of the same OD and length. Thicker wire also raises the solid height. If you need a softer return force, choose a smaller wire diameter; for heavier loads or higher resistance, select a larger wire diameter. Exact spring rates for each variant are not published; contact us if you need calculated values for your design.
These springs are made from carbon steel, which offers good mechanical properties but limited corrosion resistance in wet or humid environments without additional protection. For outdoor or moisture-exposed applications, consider applying a light coat of machine oil or grease, or contact us about stainless steel alternatives if your application demands higher corrosion resistance.
Yes. The smaller wire diameter variants (0.3–0.6 mm) with narrow ODs (2–6 mm) are well-suited for PCB test probes, pogo-pin assemblies, and small electronic enclosure latches. Ensure the spring OD clears any surrounding components and that the spring rate is appropriate for the contact force required by your test fixture.
The 21-piece bundle (0.6×4.2×210 mm) is a shorter spring at 210 mm free length and is sold as a pack of 21 springs — useful when you need multiple identical springs for a batch repair or production run. All other variants in this listing are 300 mm free length and sold individually. Select the bundle variant from the Spring Size dropdown if you need the multi-pack.
Use a digital caliper to measure: (1) outer diameter — measure across the widest point of the coil; (2) wire diameter — measure the thickness of the wire itself; (3) free length — measure the spring at rest, uncompressed. Match these three values to the Spring Size option in the dropdown (format: wire dia × OD × free length, all in mm). If your existing spring is slightly different, choose the closest available size and verify fit before full installation.
These are light-to-medium duty compression springs intended for DIY, repair, and light engineering applications. The larger wire diameter variants (1.6–2.0 mm) can handle moderate loads, but they are not rated for heavy automotive suspension or high-cycle industrial machinery. For safety-critical or high-load applications, consult an engineer and verify the spring rate and fatigue life against your requirements.
