One thing I like do when I conduct shop audits throughout the country is to ask the technicians if I can see their torque wrenches since they are vital precision measurement tools. The proper maintenance and recalibration of torque wrenches are required.
I frequently can’t get answers from technicians when I ask when they last calibrated their torque wrenches. Most people are shocked when I tell them that they can calibrate clicker-style torque wrenches on their own. Although sending it to a professional might be preferable, doing this calibration yourself is still preferable to not doing any at all.
I’ll walk you through the steps to check the calibration of the torque wrench below. We’ll also talk about the adjustments you can make if the calibration reveals that it isn’t providing accurate readings for the designated torque setting.
Table of Contents
Why is Torque Wrench Calibration Necessary?
The overall cost of ownership of the tool is significantly impacted by torque wrench calibration. A torque wrench must be calibrated in order to have its accuracy confirmed. In addition to measuring accuracy, calibration also assesses the wrench’s dependability for daily work tasks. Any error above the 5% tolerance for calibration error could have a negative impact on the tool’s performance.
How Frequently Should One Calibrate the Torque Wrench?
Many people who frequently use torque wrenches or who work in quality control in workshops frequently ask how often torque wrench calibration should be done. The intervals for torque wrench calibration don’t actually follow a one-size-fits-all procedure. For a wide range of tasks, different types of wrenches are required, and each one needs to be calibrated after a predetermined amount of time for it to work properly.
A very common fallback is calendar-based calibrations (for example, six months). However, this does not necessarily imply that calibrating the torque wrench every six months will keep it in top working order. In the end, it all narrows down to how often and aggressive the tool has been used.
The frequency of torque wrench calibration mainly depends on the user and the frequency of usage. The torque wrench calibration process is not subject to any rigid deadlines or requirements. According to some experts, 2,500–3,000 repetitions can have an impact on a tool’s performance. As a result, it is typically advised to calibrate the torque wrench 2,500 times.
Step-by-step Guide
Step 1: Capture Your Measurement
Always measure your torque wrench from the square drive’s center, where the socket is attached. To simplify your calculations, use whole inches rather than partial inches. Mark the handle where your measurement stops last. I usually write with a permanent black marker. I made my mark at 15 inches using an 18-inch torque wrench, which is the standard length for a torque wrench and the measurement we will use for this tutorial. You’ll need to remember this measurement, so make a note of it.
Step 2: Secure Your Torque Wrench
If you have a vise that you can lock your torque wrench into, this step will go more smoothly. If a vice isn’t available, use your torque wrench with a socket attached, and fasten the socket and wrench to the lug nut of the object being worked on. For the calibration test, make sure you have enough vertical space to attach a rope and weight. To prevent damaging your drive by overtightening, place the square end of your torque wrench in your vise or, if using that method, your lug nut.
In order to prevent your bench from obstructing the rope and weight, turn the handle outward. Make sure the square drive is the only object in your vise that is clamped, so the handle can move as freely as possible. If doing this on a piece of equipment, place cardboard behind the wrench so you do not accidentally damage the equipment body by the weight hanging from your rope. And wear steel-toe or composite-toe shoes or boots, in case something slips and the weight comes crashing down.
Step 3: Performing Your Calculations
You must multiply the distance from step one by whichever weight you plan to use to calculate inch-pounds in order to get the correct torque wrench setting. (We’ll use a 20-pound weight for this illustration.) Then divide that number by 12, which will give you the foot-pounds. Keep in mind, if you are using different measurements or lengths, your numbers will be different.
So our calculations look like this:
• 15 inches x 20 pounds = 300 inch-pounds
• 300 inch-pounds / 12 = 25 foot-pounds
Step 4: Securing Weight to Perform Calibration Check
• Tie the rope or cable around your weight
• Make a loop at the other end that is large enough to slide over your torque wrench handle easily. (The rope should be long enough so that the weight won’t touch the ground.)
• Set your torque wrench to 25 foot-pounds
• Hang the loop end of the rope on your torque wrench where you made your mark in step one (15 inches for us) so that the weight is now suspended.
Set your torque wrench to 26 foot-pounds if it clicked once, indicating that the weight had been applied. Your torque wrench is already accurate if it did not click. You will need to continue making adjustments to your torque wrench by following the steps below if it did click.
Step 5: Adjusting Your Torque Wrench
By tightening the tension spring, you can typically adjust your torque wrenches. These are located along the middle of your torque wrench or under your handle, which will require a little more work to access. It also may require altering your measurements to make your adjustments with the weight attached if your mark falls on the set screw placement. Make sure your torque wrench is still set to the foot-pounds determined by the calculation you performed in Step 3.
Some Tips
• With weight on the mark you made in step 1, suspend the rope’s loop end. (This may be different if you had to remove the handle to access the set screw.)
• Remove the weight and gradually tighten the set screw clockwise if you did not hear it click.
• Check to see if the adjustment was sufficient by hanging the loop end of the rope while placing your weight back on the torque wrench mark. Repeat this procedure as necessary until you hear the click, if you do not hear it the second time.
• Once you hear a click, take off the weight and re-attach your handle, if you had to take it off to make the adjustment.
Conclusion
Now your torque wrench has been tested, and you can feel comfortable that your tool is applying the appropriate amount of torque. Send your torque wrench to a professional for adjusting if you can’t do it yourself using these techniques, or get a new one.
FAQs
Do You Really Need to Calibrate Torque Wrench?
Depending on the frequency, extent, and type of usage over time, a torque wrench needs to be calibrated on a regular basis. By learning about when to calibrate the torque wrenches, one would easily be able to correct the performance every time and attain reliable final results.
How Do I Know If My Torque Wrench is Accurate?
Before you load the equipment, secure the clamp plate. When loading the torque wrench, turn the handwheel smoothly. There should be a torque transducer connected to a display instrument to measure the applied torque. You can tell if the wrench is calibrated properly by looking at this.
How Much Does It Cost to Calibrate a Torque Wrench?
The simple answer is “25 to 200 dollars, depending.” But in truth, the answer is a bit more complicated than you might expect, with a few different variables in play. To begin, ascertain the wrench’s capacity. Typically, the higher the capacity, the greater the cost of calibration.
What is the Best Way to Test a Torque Wrench?
At the 15-inch measurement, tie a rope (lightweight nylon rope was used in our demonstration) to the weight to secure it to the torque wrench handle. After being hung, make sure the weight doesn’t touch the ground. Check to see if the wrench clicks. If it does, you’re good to go.
