How to Calibrate a Torque Wrench

A torque wrench is a very useful tool that is used to apply a certain amount of torque on a nut or a bolt. It is like a socket with additional functionalities. Accuracy is a very important attribute of a torque wrench. So, if you want to calibrate your wrench and right now you want to know how to calibrate a torque wrench, you are on the right page.

You need to tighten the bolts and nuts in a right manner. You should not tighten it too much or you should not let it too loose. You need to follow the manufacturer’s recommendations for torque. The torque makes sure that you do not over tighten the bolts or nuts.

Torque wrench calibration is necessary for the torque wrench to show the results accurately. It is also important for the safety of the car and its driver. You can calibrate your torque wrench by following some easy steps.

Torque Wrench:

There is a wide range of torque wrench. The most useful torque wrench for the home mechanic is a click wrench.  They are somewhat similar to the ratchet wrench. The ratchet wrench has a head that carries a switch for setting clockwise or counter-clockwise operation. It also carries a handle to supply extra leverage. A torque wrench generally has a pivot point just below the head. When you reach an appropriate breaking force, the pivot gives an audible sound of “click” which indicates that the proper torque has been achieved.

Following are some of the types of torque wrench available in the market:

The Electronic Torque Wrench:

You can program electronic torque wrenches. There is also a set limit, by which you can determine the torque level. A strain gauge is there to send a signal to a transducer, which determines the force of torque per unit. This reading is shown in LED readings.  There is a small chip, which can record the readings.

The Click Wrench

The click wrench is similar to the socket wrench, but a little more sophisticated.  You can preset the level of torque according to the requirement. Once you reach to the desired torque level, the clutch then moves to show the required level.

The Beam Wrench

It is a simple type of torque wrench. A lever arm separates the wrench head from the handle. The lever arm is somewhat elastic, which allows the torque wrench to bend slightly at the level of pressure. A scale is there which slips to give a reading the moment you apply the torque.

Plumbers Wrench (No-Hub)

The plumbers wrench is a special purpose torque wrench, which is used for the couplings on soil pipes. The T shaped handle looks like a ratchet wrench but it has been pre-calibrated to slip when the desired level of torque is applied.

The Hydraulic Torque Wrench

A hydraulic torque wrench exerts very heavy torque to a fastener. An appropriate pressure is applied with a pre-calibrated torque. Lubrication is very important in these kinds of torque wrench. These kinds of wrench are used in automobiles where a lot of pressure and power is needed to fasten the nut or bolt.

The Deflecting Beam Wrench

This type of wrench gives high accuracy and better safety while dealing with higher levels of torque pressure. There is an audio effect, which helps the user to make sure that the required amount of torque has been generated.

You can calibrate your torque wrench at your house. This is not difficult. There can be situation where you are not sure about how to calibrate a torque wrench. If you are in such a condition, you can follow these east steps to calibrate your torque wrench at home:

Marking Points:

You have to first spot and mark the center of the wrench head on the back of the torque wrench using a pen or a marker.

Taking the Measurements:

The next step is to take the measurements. You need to measure the center point to that point where the pressure is at its maximum when you use the wrench. Note this measurement as ‘distance one’. If wrench measures in inch pounds, note this measurement in inches as ‘distance one’. If the wrench measures in feet pounds, note down the measurement in feet.

Using the Weights:

You can take the help of a vise to clamp the wrench in a horizontal direction. Using a string, you can hang a twenty-pound weight from the wrench.

Total Measurements:

You need to move the weight along the wrench handle until the reading shows 40-foot pounds or 480-inch pounds. The distance between the center point on the wrench head to the string is your “distance 2.”

Calibration Ratio:

Now you have distance 1 and distance 2. Divide distance 2 by distance 1 and this is your calibration ratio.

Setting Torque Wrench:

You need to set your torque wrench according to your application. You need to look for the torque of the bolt from the manual. Multiply the required torque of the bolt by the calibration ratio. This is our torque wrench.

You should calibrate your torque wrench annually. The price is not much for a torque wrench. You can expect it to be about $25 to $35. You should take your torque wrench to a trusted shop to be calibrated properly. You can also buy a digital adapter for torque, which can help you to calibrate the wrench accurately. You can buy a digital torque for $50.

Storage:

You should lubricate your torque wrench frequently. It is a good practice to turn the scale back to zero after each use. This helps the spring inside the wrench to rest. This also helps in retaining the calibration ratio of the torque wrench.

A torque wrench is a necessity when you are going on a long trip in a car. You may need it any time. So it is good to always carry a torque wrench with you. Even when the calibration of your wrench gets disturbed, you should go through this paper one time to know how to calibrate a torque wrench.


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