Compression Spring 3mm Wire Diameter 16–20mm Outer Diameter Small Spring Steel

Measure the inner diameter of the bore or the outer diameter of the guide rod your spring will seat against. For a bore-guided spring, the OD should be 1–2mm smaller than the bore ID to allow free movement. For a rod-guided spring, the inner diameter of the spring (OD minus 2× wire diameter) should be 1–2mm larger than the rod OD. With a 3mm wire diameter, the inner diameter is approximately OD − 6mm (e.g., a 16mm OD spring has roughly a 10mm ID).

The free length should be long enough to provide the required working travel plus the compressed (solid) height. As a conservative rule, choose a free length at least 20–30% longer than your required stroke to avoid coil bind. For example, if you need 30mm of travel, a free length of 40–50mm is a reasonable starting point, depending on the number of active coils.

These springs are made from spring steel, which provides strong mechanical properties but has limited inherent corrosion resistance compared to stainless steel. For outdoor, humid, or chemically exposed environments, we recommend applying a light coat of corrosion-inhibiting oil or grease, or considering stainless steel springs for long-term outdoor use. Contact us to confirm surface treatment options.

Load capacity depends on the wire diameter, OD, free length, and number of active coils — all of which interact to determine the spring rate (N/mm). A 3mm wire diameter spring in this OD range is suited for medium-duty loads. For precise load requirements, please contact us with your target spring rate or deflection force so we can confirm the best variant for your application.

Yes. The closed-end coil geometry allows these springs to seat flat on standard spring seats. They are compatible with guide rods sized to fit within the inner diameter of the selected OD variant. Always verify that the guide rod OD is at least 1–2mm smaller than the spring's inner diameter (OD − 6mm for 3mm wire) to prevent binding during compression.

Yes. These compression springs are well-suited for DIY automation rigs, CNC bed-leveling mechanisms, extruder return assemblies, and custom fixture clamps. The consistent coil geometry and spring steel construction support repetitive cycling. Select the OD and free length that match your travel and force requirements, and order in the pack size that suits your build quantity.

All three pack sizes contain identical springs — the only difference is quantity and unit price. The 20-piece and 50-piece packs offer a lower per-unit cost, making them more economical for production runs, workshop stock, or projects requiring multiple springs. The 10-piece pack is ideal for prototyping or single-unit repairs.