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When a mechanism demands exact rotational force and reliable return motion, a mismatched or low-tolerance spring causes premature failure, misalignment, and costly downtime. Engineers, toolmakers, and DIY builders who need a left-hand wound torsion spring with consistent coil geometry will find this series purpose-built for demanding applications.
Each left-hand torsion spring in this series is formed from 0.8mm wire diameter steel, with outer diameters ranging from 5mm to 10mm (approximately 0.20 in to 0.39 in). Coil counts span 3 to 9 turns, and leg angles are available in 60°, 90°, 120°, and 180° to match your assembly geometry precisely.
Typical use cases include compact hinge mechanisms requiring left-hand torsion spring return force, precision instrument assemblies where a 0.8mm wire torsion spring fits tight clearances, and custom jig or fixture builds needing a small outer diameter torsion spring with selectable leg angle.
| Wind Direction | Left-hand (counter-clockwise) |
|---|---|
| Wire Diameter | 0.8 mm (0.031 in) |
| Outer Diameter Range | 5 mm – 10 mm (0.197 in – 0.394 in) |
| Inner Diameter Range | 3.4 mm – 8.4 mm (approx., OD − 2× wire Ø) |
| Active Coils | 3, 4, 5, 6, 7, 8, or 9 coils (select variant) |
| Leg Angle | 60°, 90°, 120°, or 180° (select variant) |
| Material | See variant options |
| Surface Finish | See variant options |
| Free Angle | See variant options |
| Spring Rate | See variant options |
| Max Working Torque | See variant options |
Measure the bore or housing your spring will sit in, then select an outer diameter slightly smaller to allow clearance. For mandrel-mounted springs, measure the shaft diameter and choose an inner diameter (OD minus twice the wire diameter, so OD − 1.6mm) that gives a snug but free-sliding fit. Use the variant selector above to pick your outer diameter from 5mm to 10mm.
A left-hand (LH) torsion spring is wound counter-clockwise when viewed from the front. When the spring is loaded in its intended direction, the coils tighten, increasing the spring's effective rate. Using a right-hand spring in a left-hand application — or vice versa — causes the coils to open under load, reducing rate and risking disengagement. Always confirm your mechanism's rotation direction before ordering.
More active coils increase the angular deflection the spring can absorb before reaching its stress limit, and they reduce the spring rate (torque per degree). Fewer coils produce a stiffer spring with less total travel. If your application requires a large working angle (e.g., 90° or more of deflection), choose a higher coil count. For stiff, short-travel applications, 3–4 coils are typically sufficient.
The leg angle is the angle between the two straight legs of the spring in its free (unloaded) state. Select the angle that matches your assembly's geometry so the legs seat correctly against their bearing surfaces without pre-stressing the spring. A 90° leg angle is the most common for hinge and latch applications; 180° (straight legs) suits applications where both legs must point in opposite directions.
Corrosion resistance depends on the material and surface finish of the specific variant. Please refer to the variant details or contact us to confirm the material specification for your selected SKU. For outdoor or humid environments, consider requesting a stainless steel or coated option if available in this series.
Torsion springs of this wire diameter and coil geometry are suitable for moderate-cycle applications such as hinges, latches, and instrument mechanisms. For high-cycle fatigue applications (millions of cycles), consult the spring rate and stress data for your selected variant and ensure the working deflection stays within the recommended range. Contact us to confirm suitability for your specific duty cycle.
Each combination of wire/outer diameter, coil count, and leg angle has a unique SKU (e.g., LXX-KDL3765x1 for 0.8×5mm / 3 Coils / 60°). Record the SKU from your original order or from the variant selector on this page. You can also use the SKU as a barcode reference for inventory management.
