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How To Calibrate A Torque Wrench

Table of Contents

Is your torque wrench giving you inaccurate readings and making project completions difficult?

The problem is most likely improper calibration, which causes inaccuracies in torque measurements.

Thankfully, this issue has a pretty straightforward fix!

Today, we’ll tell you how to calibrate a torque wrench.

In just five short steps, you can get your torque wrench to function with complete precision.

If you’re wondering how to do this, you’re in the right place.

Keep reading to find all you need to know about torque wrench calibration.

How To Calibrate A Torque Wrench

To calibrate your torque wrench, you will need the following materials:

  • A marker or pen
  • A vice secured to a surface
  • Torque wrench
  • Weights ranging from twenty to thirty-five pounds
  • Tape measure
  • A piece of paper to note down calculations
  • Safety shoes with reinforced toes
  • Load rotating rope or strong string

Step One: Make the Measurements

Measure the distance between the end of the torque wrench and the handle.

It is easier to work in whole numbers instead of decimals, so round up or down wherever necessary.

To guarantee that you don’t forget the value, write it down on a piece of paper because you’ll need it later. 

Step Two: Secure the Wrench to The Vice 

First, secure your vice onto a surface such as a table.

The end of the wrench, which is also called a square drive, has to be placed into the vice facing away from the table or surface you will be working on. 

Be careful when tightening the wrench’s square drive into the vice! You do not want the square drive to be too loose or too tight because that can ruin the torque wrench.

After this step has been completed, try to move your wrench around.

Only the square drive should be fixed to the vice. The rest of the wrench should be free. 

Step Three: Make the Calculations

The formula that you will use for the calibration is:

To calibrate your torque wrench, you’ll need to hang a weight from the wrench’s handle.

The weight used to check for calibration can differ depending on the torque wrench you own and the weights you have available. 

Twenty pounds is usually what is used to check the accuracy of a torque wrench.

All distances should be in inches, and the weights should be in pounds. The final product will be in foot-pounds. 

Step Four: Check the Calibration 

Now, you have to tie a rope to the weight you are using and make a large enough loop through which you can slide in your wrench’s handle.

Ensure that the rope rests on the mark you made on the handle in Step 1.

The rope should be short enough so that the weight stays above the ground at all times, and it isn’t hindered by anything. 

To begin the test, let your weight hang freely and set the torque wrench to the calculation you just made.

The torque wrench will emit a single click sound if it is calibrated.

If you hear nothing, please move on to step five to make the needed corrections.

Step Five: Make Modifications

If there was no click in step four, you would have to adjust the spring tension.

This is located halfway on the handle of the torque wrench.

The spring can easily be loosened or tightened with a screwdriver.

In some wrenches, the tension spring is underneath the handle, and you will have to unscrew the handle to reach the spring. 

If your torque wrench did not click in step four, tighten the spring by turning it clockwise with a screwdriver.

Then, lift the weight and lower it to test the wrench again.

If it clicks, great! But, if it doesn’t, tighten the spring once more and try again.

Once you hear a click, move the weight further up the wrench, closer to the head, and check for a click.

Repeat this process until you stop hearing the click.

In some instances, you may not be able to hear a click when the weight is hanging on the mark you make.

In this case, move the weight further away from the head until you hear a click.

Measure the point from the square drive to this point, also known as the transition point.

After making these adjustments, repeat step four and make sure you can hear the clicks at whatever torque setting you are using.

The clicks identify proper calibration.

If you had to take off the handle, this is when you should reattach it. 

Can You Calibrate Your Own Torque Wrench?

How To Calibrate A Torque Wrench

Yes, you can calibrate a torque wrench on your own.

We recommend you go to a professional if you have never worked with torque wrenches before.

However, if you are somewhat familiar with them, you should calibrate them by yourself.

If you follow the steps mentioned above and have all the necessary tools at home, taking on this quick project should be easy. 

This will be quite beneficial for you because the next time your torque wrench shows incorrect measurements, you can fix it immediately.

How Much Does It Cost to Calibrate A Torque Wrench?

The cost to calibrate a torque wrench can cost anywhere from $50 to $150, depending on the pound-foot of your torque wrench.

If you choose to calibrate a torque wrench at home, the cost incurred will be one-time instead of a recurring one. 

This is because you will only have to buy most of the materials needed to calibrate a torque wrench only once.

This includes the safety toe shoes, the vice, weights, and ropes to hold the weights.

Everything together should cost you between $100 to $150 approximately.

How Do I Know If My Torque Wrench Is Accurate?

Torque Wrench settings

To check whether your torque wrench is reading the correct measurements after you have calibrated it, you can use one of these two tools: 

1. Torque Loading Bench

The torque loading bench sits on a level surface and has a wheel that can check the force of a torque wrench. 

To attach the torque wrench, you will put it on the lowest capacity transducer, which is on top of the loading bench.

Slide the loading assembly across the reaction bar, making some room for the wrench to be input.

The handle of the torque wrench should go in the same direction as the bar. 

This instructional video may help you use the loading bench right.

Once the torque wrench is correctly attached to the machinery, start turning the wheel to apply force onto the wrench.

There is a display on the device that identifies whether the torque wrench has been correctly calibrated.

If it has not, you will be notified via the screen if the force applied was unsatisfactory.

2. Torque Analyzer

To begin the test, you have to use the torque wrench and exert force on the input end of the device.

When you do this, the screen will flash a reading that tells you how your torque wrench compares to an ideal wrench’s output.

The same screen will let you know what you need to change if your wrench isn’t working correctly. 

How Often Do Torque Wrenches Need to be Calibrated?

A torque wrench needs to be calibrated once every year or after its five thousandth cycle, whichever occurs first.

If you don’t maintain your torque wrench well, its accuracy will deteriorate with time.

This can affect any projects you use the torque wrench on.

If you use it excessively, it may be an excellent idea to attune it more frequently to avoid unwanted errors. 

Those working with torque wrenches are dependent on them giving the correct reading, which can only be done if they are properly calibrated.

When using an uncalibrated torque wrench, you can get somewhat accurate measurements by multiplying the measurement you get by:

If used without calibration, the force-torque wrenches apply to the nuts and bolts will be incorrect.

When this happens, whatever vehicle or engine you are working on will be left with faulty screws that can be a hazard while driving.

A wrongly calibrated torque wrench can attach a tire to a car too loosely, causing an accident when it is driven.

Therefore, to limit the chance of injury and increased repair costs, you should consistently check on your torque wrench to see if it works the way it should be.

Summing Up

Can You Calibrate Your Own Torque Wrench?

Working with a torque wrench is difficult, but if you dedicate time to maintenance, you can avoid many unwanted issues related to inaccurate measurements.

By now, though, you should have learned how to calibrate a torque wrench on your own!

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