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When a machine stops returning to position, a door fails to close cleanly, or a jig loses its clamping force, the culprit is often a worn or incorrectly sized compression spring. Engineers, makers, and maintenance technicians who need a dependable replacement or a precisely specified spring for a new build will find this range covers the most common coil spring requirements without compromise.
These compression springs are wound from carbon steel wire with a uniform 4 mm wire diameter. The outer diameter spans from 36 mm to 70 mm (approximately 1.42 in to 2.76 in), and free lengths range from 20 mm to 400 mm (approximately 0.79 in to 15.75 in), giving you the flexibility to match the spring to your exact cavity or travel requirement. Each listing ships in small packs of 1–5 pieces depending on the selected length variant.
Typical applications include CNC router Z-axis return mechanisms, pneumatic fixture clamps, industrial valve actuators, 3D printer bed leveling assemblies, and custom robotics linkages where a consistent restoring force is required across repeated cycles.
Consistent 4 mm wire cross-section across all variants ensures predictable spring rate and load capacity for medium-duty compression applications.
Outer diameters from 36 mm to 70 mm and free lengths from 20 mm to 400 mm let you select the exact geometry your assembly requires.
Wound from carbon steel wire for a firm spring rate and long fatigue life under repeated compression cycles in mechanical and industrial environments.
Squared and ground end coils provide a flat seating surface, reducing lateral deflection and ensuring the spring sits squarely in its pocket or on its guide rod.
Available in packs of 1, 2, 3, or 5 pieces depending on the selected length, so you can order exactly what your project needs without excess stock.
Suited for CNC machines, robotics, pneumatic fixtures, valve assemblies, 3D printer beds, and general mechanical engineering where a reliable restoring force is needed.
| Wire Diameter | 4 mm |
|---|---|
| Outer Diameter | 36 mm – 70 mm (see variant options) |
| Free Length | 20 mm – 400 mm (see variant options) |
| Material | Carbon Steel |
| End Type | Closed & Ground (squared ends) |
| Wind Direction | Right-hand |
| Finish | See variant options |
| Spring Rate | See variant options |
| Pack Quantity | 1 / 2 / 3 / 5 pcs (depends on selected length) |
Measure the bore or pocket that will house the spring to determine the maximum allowable outer diameter, then subtract 1–2 mm for clearance. For the free length, add your required travel (compression stroke) to the desired compressed length. Select the variant whose outer diameter and free length best match those calculated values.
The load capacity depends on the outer diameter, free length, and number of active coils — all of which vary by variant. As a conservative guide, 4 mm wire carbon steel springs in this size range typically handle light-to-medium loads. For precise load and deflection data, contact us with your selected variant dimensions and we can provide further guidance.
These springs are made from carbon steel without a protective coating, so they are best suited for dry indoor environments. For applications exposed to moisture, humidity, or mild chemicals, consider applying a light machine oil after installation or contact us about stainless steel alternatives.
Yes, provided the guide rod outer diameter is smaller than the spring's inner diameter (outer diameter minus twice the wire diameter, i.e., OD − 8 mm), and the pocket bore is larger than the spring's outer diameter by at least 1 mm. Always verify clearances before installation to prevent binding.
Yes. These compression springs are commonly used in CNC router Z-axis return mechanisms, 3D printer bed leveling systems, and fixture clamps. Select the variant whose outer diameter fits your spring pocket and whose free length provides the travel and preload your design requires.
Pack quantity varies by the selected length variant: shorter lengths (20–100 mm) typically ship in packs of 5 pieces; medium lengths (100–200 mm) ship in packs of 2–3 pieces; longer lengths (200–400 mm) ship as 1 piece per pack. The exact quantity is shown in the variant name (e.g., "50 mm & 5 pcs").
Free length is the overall length of the spring when no load is applied — this is the dimension listed in the variant name. Compressed length (solid height) is the length when all coils are touching. Your working stroke must fit between these two values. Always leave at least 10–15% of the free length as a safety margin above solid height.
