How to Measure Torsion Springs
You can easily measure torsion spring properties by understanding the vital geometric features and a few simple steps and tools. If you are trying to redesign or replace an existing compression spring, then it is critical that you precisely and accurately measure all relevant dimensions, because torsion springs are usually small components manufactured to tight tolerances.
Furthermore, precision spring manufacturing is essential because torsion springs are highly engineered components that deliver reliable performance for long product lifetimes. Lastly, you should also understand how each torsion spring dimension impacts parameters such as the spring rate and how these properties affect the spring performance in the application.
After we have shown you how easy it is to measure torsion spring properties, you will be ready to shop our Torsion Spring Selection for thousands of in-stock springs available for immediate shipping and custom spring design options.
Essential Tools for Measuring Torsion Springs
A caliper and a protractor are all you need to measure compression springs. A caliper is a device used to measure linear dimensions, thickness, or diameter. Dial or digital display calipers will both work for performing the following measurements on compression springs. You may also use a micrometer in place of a caliper to measure the wire size. The protractor will allow you to measure the angle between the torsion spring legs.
Understanding Torsion Spring Specifications
The critical physical parameters for torsion springs are identified below.
1. Wire Diameter: The spring wire is the circular metal wire wound into a helical coil. As such, the wire diameter is simply a measure of the diameter of this part of the spring. The thicker the spring’s wire diameter, the larger the spring rate, and the stronger the spring.
2. Inner Diameter (ID): The spring’s ID is the diameter of the coils measured from the inner surfaces of the helical coils. The inner diameter is also a function of the outer and wire diameters. The ID of a torsion spring is a critical dimension in applications where a mandrel is designed to fit inside the torsion spring. As load is applied to the torsion spring, the torsion spring legs rotate while the ID of the spring shrinks.
3. Leg Length: The torsion spring legs are the straight wire portions of the spring that serve as the interface between the coils and the mechanism applying loads to the spring. Torsion spring leg lengths are always specified from the center of the torsion spring ID to the end of the leg.
4. Body Length: The spring’s body length is the length of the spring from one end of the body to the other. The bigger the body length, the more coils in the torsion spring.
5. Number of Coils: The number of torsion spring coils is simply the number of helical coils that make up the body of the torsion spring. As the number of coils on a torsion spring increases, the spring rate decreases, meaning it takes less force to rotate the legs of the torsion spring through a given angle.
6. The Angle Between the Legs: This is the angle at which the legs of the spring are positioned relative to each other when the spring is unloaded. This angle determines how the spring fits into the intended application.
Step-by-Step Guide to Measuring a Torsion Spring
Measuring the Body Diameter
Place the spring's body between the outside large caliper jaws until they contact both ends. Make sure the caliper is straight and perpendicular to the spring body. Then, read the measurement from the caliper display.
Measuring the Wire Diameter
Locate one of the torsion spring legs and place the outside large caliper jaws around this wire, ensuring the jaws touch both sides. Take the reading from the caliper at this location. To verify the measurement, you should measure the wire diameter at both torsion spring legs. You can also use a micrometer to measure the torsion spring wire diameter.
Measuring the Inside Diameter
Insert the small jaws of the caliper into the spring's helical coil to measure the torsion spring's inner diameter. You can also calculate the spring's inner diameter (ID) by subtracting twice the wire diameter from the spring OD.
Measuring the Leg Length
You can use a caliper to measure leg length accurately by measuring the torsion spring leg from the center of the spring ID to the end of the straight leg. You can also measure the leg length from where it comes off the torsion spring OD and then add this value to half of the spring OD to calculate the torsion spring leg length.
Counting the Number of Coils
Place the torsion spring flat on its side and carefully count the total number of coils on the spring. Be sure to include partial coils in your count because the number of torsion spring coils gives you a clue to the angle between the torsion spring legs because each full 360-degree rotation is a coil count.
Measuring the Angle between Torsion Spring Legs
You can measure the angle between torsion springs using a protractor. When using a protractor, you should always measure the angle between the legs toward the direction the load will be applied. This is the winding direction of the spring.
Determining the Torsion Spring Wind Direction
A torsion spring’s wind direction is denoted as either right-hand or left-hand wind. You can quickly determine your torsion spring’s wind direction by noting that a right-hand wind spring is coiled counter-clockwise while a left-hand wind spring is coiled clockwise.
Tips for Accurate Torsion Spring Measurement
Before taking any measurements, be sure that the measurement surfaces on the calipers and the compression spring are clean and free of dirt and debris. Before taking any measurements, you should calibrate all hand tools.
Additionally, you should always take multiple measurements at several locations and average the values together to ensure consistency. Lastly, before recording any measurement, you should always verify that the caliper jaws are square against the measurement surfaces.
Additional Torsion Spring Properties to Measure
Some torsion springs do not have straight legs but feature legs with multiple bends. All bend radii should be measured and recorded if they are critical design dimensions.
Furthermore, double torsion springs feature two other important design parameters, such as the Hairpin Inner Diameter (ID), the distance between the arms connecting the two springs to form a double torsion spring. The second dimension is the Hairpin Length, which is the dimension of the legs that connect the two springs.
For more information about torsion spring measurements or to receive answers to any other questions, you can Consult with our Experts at any time!
Ensure Precision with Century Spring
Century Spring is an established manufacturer that has produced high-quality springs for over 100 years. You can rest assured that every torsion spring in every order meets the most rigorous design and manufacturing specifications. We specialize in stock and custom springs and offer lightning-fast fulfillment on over 40,000+ in-stock designs available to ship today!
Now that you have mastered the critical torsion spring properties, you can Shop In-Stock Torsion Springs or Request a Quote today.
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