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When a repair stalls because a tiny spring snapped or went missing, finding the right replacement fast matters. Hobbyists, electronics repair technicians, model makers, and mechanical engineers working with compact assemblies need small compression springs that deliver consistent force without taking up space. These 10-piece small compression springs are engineered for exactly those situations — available in wire diameters of 0.3 mm and 0.4 mm, with outer diameters spanning 2 mm to 10 mm and lengths from 5 mm to 50 mm.
Each set contains 10 identical springs made from steel wire, wound into a cylindrical open-coil form. Wire diameter options are 0.3 mm (~0.012 in) and 0.4 mm (~0.016 in). Outer diameter ranges from 2 mm (~0.079 in) to 10 mm (~0.394 in). Free lengths run from 5 mm (~0.197 in) to 50 mm (~1.969 in). The coil geometry provides linear spring force when compressed axially between two surfaces.
Typical use cases include replacing worn return springs in mechanical keyboards and clicky switches, restoring tension in pen mechanisms and retractable tools, providing preload in small sensor assemblies and jig fixtures, and acting as cushioning elements in 3D-printed enclosures or prototype mechanisms. The compact size range also suits watchmaking, jewelry clasps, and fine instrument repair where standard hardware-store springs are far too large.
Choose from wire diameters of 0.3 mm or 0.4 mm combined with outer diameters from 2 mm to 10 mm and free lengths from 5 mm to 50 mm — covering a broad range of precision replacement and prototyping needs in a single product listing.
Wound from steel wire, these springs deliver reliable elastic return force across repeated compression cycles. The material provides the stiffness-to-size ratio needed for small mechanical assemblies where space is constrained.
Each order ships as a set of 10 identical springs, giving you spares for future repairs or enough quantity to populate a small batch of assemblies without ordering in bulk. A 1000-piece option is also available for the 0.4 mm × 4 mm OD × 10 mm variant.
Open-coil cylindrical winding ensures uniform pitch and predictable linear force response. Springs seat flat on both ends, making them straightforward to install in bored pockets, guide pins, or between parallel plates.
Used in mechanical keyboards, pen mechanisms, sensor preload fixtures, 3D-printed prototypes, watchmaking, jewelry clasps, and fine instrument repair — anywhere a standard hardware spring is too large for the available space.
Three independent variant axes — Wire Diameter, Outer Diameter, and Length — let you dial in the exact spring geometry your application requires rather than settling for a close-enough off-the-shelf size.
| Spring Type | Cylindrical Open-Coil Compression Spring |
|---|---|
| Material | Steel Wire |
| Wire Diameter | 0.3 mm or 0.4 mm (see variant options) |
| Outer Diameter (OD) | 2 mm – 10 mm (see variant options) |
| Free Length | 5 mm – 50 mm (see variant options) |
| Coil Direction | See variant options |
| End Type | Open ends (standard coil) |
| Quantity per Pack | 10 pcs (1000 pcs available for select variant) |
| Surface Finish | See variant options |
| Spring Rate | Contact us to confirm |
Wire diameter determines the stiffness of the spring. A 0.4 mm wire produces a stiffer spring than a 0.3 mm wire of the same OD and length. If you need a lighter return force — for example in a pen click mechanism or a delicate sensor — choose 0.3 mm. For applications requiring more resistance, such as a latch or a button with tactile feedback, 0.4 mm is the better choice. When in doubt, measure the original spring's wire with calipers before ordering.
The outer diameter must be smaller than the bore or pocket that houses the spring, and larger than any guide pin running through the spring's center. As a rule of thumb, leave at least 0.2–0.5 mm clearance between the OD and the bore wall. For guide-pin installations, the inner diameter (OD minus twice the wire diameter) should be at least 0.3 mm larger than the pin diameter. Available ODs range from 2 mm to 10 mm in this listing.
Free length is the spring's uncompressed height. Choose a free length that is longer than the installed (compressed) height you need, with enough travel to generate the required force. If you are replacing a broken spring, measure the pocket depth and the gap the spring must bridge when assembled. Available free lengths in this listing run from 5 mm to 50 mm in 5 mm increments.
These springs are made from steel wire. Standard steel offers good mechanical properties but has limited corrosion resistance in humid or wet environments without a protective coating. For indoor, dry, or low-humidity applications they perform reliably. If your application involves moisture, consider applying a light coat of machine oil or contact us to confirm whether a coated variant is available for your size.
Yes. The small OD range (2–10 mm) and short length options (5–15 mm) make these springs well-suited for use as contact springs, battery terminal springs, or tactile return elements in PCB-mounted switches. Ensure the spring does not bridge unintended electrical contacts, and verify that the spring's conductivity is acceptable for your circuit design.
The standard listing sells 10 identical springs per order, which suits repair, prototyping, or small-batch assembly. A 1000-piece bulk option is available specifically for the 0.4 mm wire diameter × 4 mm OD × 10 mm length variant (SKU BGM3889x1000). If you need bulk quantities of other sizes, contact us to discuss availability.
Use digital calipers to measure the original spring or the housing pocket: record the bore diameter (to select OD), the pocket depth and compressed height (to select free length), and the wire thickness (to select wire diameter). Cross-reference those measurements against the three variant selectors — Wire Diameter, Outer Diameter, and Length — in this listing. If you are unsure, order one size up and one size down to test fit before committing to a larger quantity.
