How to Calibrate a Torque Wrench

Torque wrench calibration is important to the safety and effectiveness of your home and car repairs, as well as the functionality of the torque wrench itself. Use your torque wrench safely and effectively by calibrating it at home to suit your needs.

Things You'll Need

• Torque wrench
• Vise
• String
• 20-pound weight
• Calculator
• Marker or pencil

Instructions

1. Mark the center point of the wrench head on the back of the torque wrench. Use a a pencil or marker.

2. Measure from the center point to the point at which you apply the most pressure when using the wrench. Write down this measurement as "Distance 1" either in inches (if your wrench measures in inch pounds) or feet (if your wrench measures in foot pounds).

3. Clamp the wrench bit in a vise horizontally. Using string, hang a 20-pound weight from the handle of the wrench.

4. Move the weight along the handle of the wrench until it measures exactly 40 foot pounds or 480 inch pounds. Measure the distance from the center point on the head of the wrench to the string and write this measurement down as "Distance 2."

5. Divide "Distance 2" by "Distance 1" with the calculator to find the calibration ratio. This ratio is the difference between the the settings on your wrench and the actual force needed to acquire a "click" at that setting.

6. Set your torque wrench for a specific application by multiplying the required torque of the bolt by the calibration ratio. For example, if a bolt requires 43 foot/pounds of torque and the calibration ratio is 1.124, multiply 43 times 1.124 and set your wrench to 48.3 foot/pounds.

References

• Simple Torque Wrench Calibration

Resources

• Read this Article in Spanish
• Torque Calculation