Stock Torsion Springs - More Than 900 Designs

Think of a torsion spring as the muscle behind the twist. Instead of pushing or pulling like a typical spring, a torsion spring works by twisting—and in doing so, it creates a rotational force called torque.

Here’s the simplest way to picture it: Have you ever used a clothespin? When you squeeze the ends open, you’re actually twisting a spring in the middle. As soon as you let go, that spring wants to snap back—that’s torque in action. The same principle applies to many other items: laptop hinges, clipboards, garage doors, even mousetraps.

A torsion spring is a tightly wound coil with two arms, or “legs.” When you rotate those legs (either clockwise or counterclockwise), you twist the coils tighter. The spring stores that energy and pushes back, trying to return to its original shape. That pushback is what makes things close automatically, lock into place, or return to a starting position.

1. Wire Diameter (How thick is the spring wire?)

This is the thickness of the wire used to make the coils. It directly affects how strong the spring is and how much torque it can handle.

• How to measure it: Place your caliper across the wire itself—not across the whole spring. Measure in a few spots and average the values if needed.

• Example: You measure 0.080 inches (about 2.032 mm).
  This tells you what wire size to look for when browsing stock options.
  
  

???? Tip: Don’t guess based on appearance. A difference of just 0.005" can change the spring’s strength by a lot.

2. Outer Diameter (OD) – How wide is the spring from edge to edge?

This is the full width of the spring coil. It tells you whether the spring will fit inside a housing or slide over a shaft.

• How to measure it: Place calipers or a ruler across the widest part of the coil—from one outside edge to the other.

• Example: Your spring measures 0.500 inches (or 12.70 mm) across.
  
  

???? Important: If your spring needs to sit inside a tube or fit over a rod, this number must be exact.

3. Inner Diameter (ID) – How wide is the hole inside the spring?

This is the size of the hole down the center of the coil. It’s important if your spring goes around a rod or shaft.

• How to find it: If you can't measure it directly, subtract twice the wire diameter from the outer diameter:
  
  ID = OD - 2 × Wire Diameter
  
  

• Example:
  0.500" OD – 2 × 0.080" wire = 0.340" ID (or 8.636 mm)
  
  

???? Make sure the ID is slightly larger than the rod it will sit on—leave a little clearance.

4. Body Length – How tall is the coiled section?

This is the length of the spring’s coiled part, not counting the legs (arms). It helps you figure out how much axial space the spring will take up in your mechanism.

• How to measure it: Lay the spring on its side and measure from one end of the coil stack to the other.

• Example: The coil section is 0.880 inches (about 22.352 mm) long.
  
  

???? This is important when space is tight in your device or housing.

5. Total Coils – How many full loops?

The number of coils affects how much the spring can twist and how much torque it can produce.

• How to count: Look closely and count each full loop of wire. If one leg wraps partway around, include it as a partial coil (e.g., 4.5 coils).

• Example: You count 10 full coils with no partial coils, which is 10 coils total.
  
  

???? More coils generally means more flexibility (longer travel), but less torque.

6. Leg Lengths – How long are the spring’s arms?

Torsion springs usually have two legs that stick out from the coil. Their length affects how and where the spring attaches to your mechanism.

• How to measure: Measure from the center of the coil out to the tip of the leg. If that’s tricky, measure from the coil’s edge and add half of the outer diameter.

• Example:
  From edge to leg tip = 0.67"
  Half OD = 0.25"
  Total leg length ≈ 0.67" + 0.25" = 0.920 inches (23.368 mm)
  
  

✏️ If one leg is longer than the other, measure both and record each one.

7. Free Position– What’s the angle between the legs?

This tells you the position of the legs when the spring is at rest. It’s measured in degrees: common values are 90°, 180°, 270°, and 360°.

• How to measure: Lay the spring flat. Imagine or draw a line from the center of the coil through each leg. Use a protractor or angle template to find the angle between the legs.

• Example: If both legs form a straight line, lying flat along a surface, that’s a 0° angle. This means there’s no gap between the legs in the spring’s relaxed position—they're aligned.
  
  

???? This affects how far the spring can twist and how it fits into your assembly.

8. Winding Direction – Left-hand or Right-hand?

This is one of the most important measurements, especially if you're replacing a spring.

• How to tell: consider how the spring twist during use:

  • If it twists counterclockwise to store energy → Right-hand wind

• If it twists clockwise to store energy → Left-hand wind
  
  

↪️ Springs are designed to be twisted in the direction that tightens them. Loading a spring the wrong way can cause it to fail.

• Using Online Catalogs and Finders: On The Spring Store, you can navigate to the torsion spring stock catalog section. We provide an online spring finder tool where you can plug in your known dimensions. For instance, you can enter your measured outer diameter, number of total coils, wire diameter, free position, etc., and the tool will filter the catalog to show springs that meet those parameters. You can search in either English or metric units. There is also an option for a basic search (just a couple of inputs like OD and coils) or an advanced search where you can refine with more details (max torque,  rate, leg length, material, etc.). The interface is user-friendly – in just a few clicks, you get a list of part numbers that match your needs. Each spring listing will usually include all the specifications so you can verify it matches what you measured.

• Acxess Spring’s PDF Stock Catalog: Not only can you search online, but you can also download the full stock spring catalog PDF. Having the PDF is handy if you want to browse or compare multiple springs side by side. The catalog will list each spring’s dimensions, material (music wire, stainless, etc.), maximum torque, and a part number. You can use that part number to order directly. 

How Long Do Torsion Springs Last?

The good news is: a well-designed torsion spring can last for years—or even decades. The not-so-good news? If the wrong spring is used, or it’s pushed too hard, it could wear out in weeks. Each full twist and return is called a cycle, and most springs are rated for 10,000 cycles or more. That might sound like a lot, but in daily use, it adds up fast. Factors like how far the spring is twisted, the material (stainless steel for corrosion resistance or music wire for strength), the environment (humidity, heat, vibration), and installation quality all affect lifespan. A well-supported spring, mounted on a shaft, operating within 75–85% of its max deflection, will last significantly longer than one that’s overloaded or misaligned. For example: If you open a storage box lid just twice a day, that adds up to 730 cycles per year. With a spring rated for 10,000 cycles, it could easily last over 13 years with normal use. And because smaller springs are often under less stress and used in gentler applications, they tend to last even longer—especially if they're well-installed and protected from rust.