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Did you know that you need to calibrate a torque wrench at least once a year? This is especially true of those that are extensively used in the industrial sectors.

Automatic or electronic torque wrenches have special recalibration facilities and are best done by professionals. Coming to simple handheld torque wrenches, these too run out of their capacities after regular use and need regular recalibration.

This tool is an instrument of precision work and even a small deviation can badly affect the pairing object like a nut or a stud. To get the best out of this instrument, take care to prepare it before using it especially if you haven’t tested its calibration for a long time.

For those of you that own a personal torque wrench and wish to calibrate a torque wrench using the best DIY (do-it-yourself) method, here’s everything that you need to know.

Why Recalibrate?

Calibration is the set of reading on a tool that is done following standard methods. The readings help check the accuracy of the instrument and is a measure of its performance. This is usually done using a standard equipment or device that is pre-calibrated for this purpose. The calibration of any tool is determined by its type and industry where it is used.

A torque wrench requires care and maintenance like any other machinery for which it is used. If a torque wrench is not correctly calibrated, it is likely to exert too much pressure and break a coupling part. If less than optimal torque is applied, it is sure to result is less effective functioning of the parts. Precision is the catch word here and, conclusions can be at best disastrous!

Because calibration is the effective measure of an equipment’s valid performance, it is necessary to get it done regularly. In case of a fall or an accidental slip, the chances of an instrument’s calibration getting disturbed is very high. This is the reason that all industrial torque wrenches are recalibrated each time they are accidentally dropped.

How to Calibrate?

While professional torque wrench calibrations are required for industrial applications, you can always learn a DIY calibration technique that is useful for personal works and purposes.

There is of course some mathematics behind the calibration of a torque wrench that you need to understand. The force applied is torque which is the product of weight and distance. Torque (T) = force (weight) x distance. The torque you get is the ideal output as some amount of energy is always lost to the environment due to friction of the thread. This is one of the reasons you should keep all studs and nuts oiled at regular intervals to facilitate their easy repair and maintenance.

Things you need to calibrate
  • A 20-pound weight
  • A bench vise/vice
  • A thin rope/string
  • Measuring tape
Steps to follow

Calibrating a torque wrench by yourself is a lot simpler than you probably imagine and can be done by anyone with a little bit of care and attention.

  • Measure the torque length from the place where your hand rests to its square drive.
  • Secure the vise/vice placing only the wrench’s square drive in it securing it in turn.
  • Multiply the length that you measured in the first step by 20 pounds and set this as the value of the wrench, aligning it accordingly.
  • Tie the 20-pound weight on the wrench at the hand resting position that you measured from.
  • If there’s a click sound emanating from the system, then move the weight towards its head until the clicking sound ceases. In case there is no click sound the first time, move the weight in the direction opposite to the square drive to the point where the click emanates and move it backwards till there is no more clicking.
  • Measure the distance from this point to the square drive and multiply by 20 pounds.
  • T= F x D will give you the torque measure of your tool.

Torque is a rotational force that is exerted when you close a door or push a merry-go-round. This same force is used to fasten or unscrew. Torque wrench is used to exert the force with which the fastening can be held or unscrewed.

Torque of a wrench is lost over time while using it. Factors like temperature and the immediate climatic condition of the environment play important roles in maintaining its accuracy. Testing a torque wrench at regular intervals and calibrating it not just optimizes operations but also eliminates chances of errors and thus accidents.

While it is relatively easy to calibrate a manual torque wrench, hydraulic torque wrench and pneumatic torque wrench are highly sensitive tools that require professional testing and recalibration.

Click here to watch a Hydraulic Torque Wrench be calibrated

Get in touch with the AMG Bolting professionals to know about recalibration of your electronic torque wrench.