If you’re like most car owners, you probably have a few torque wrenches in your toolbox. They come in handy for everything from tightening the lug nuts on your car to assembling furniture. However, how do you know when your torque wrench is accurate? In this blog post, torque wrench experts will discuss how to test a torque wrench and ensure that it is giving you the correct readings.
Table of Contents
Testing Your Torque Wrench Through Recalibration
The best way to use a torque wrench is with an automatic or electronic torque wrench, which has special recalibration capabilities. With basic handheld torque wrenches, these too wear out and need to be recalibrated on a regular basis.
Calibration is the process of measuring a tool’s readings using standard techniques. The readings are used to assess the instrument’s accuracy and effectiveness.
This is generally achieved with common equipment or a gadget that has been re-calibrated for this purpose. Any tool’s calibration is determined by its kind and industry in which it will be utilized.
Calibration is the most reliable method of determining an equipment’s true performance. It is critical to have it done on a regular basis. The chances of an instrument’s calibration being disturbed if it falls or slips accidentally are quite high. This is why, whenever a torque wrench is dropped inadvertently, it must be recalibrated [1].
The Importance of Proper Torque Wrench Calibration
Torque wrench calibration is crucial to maintaining accuracy and precision while tightening fasteners. Incorrectly calibrated torque wrenches can cause damage to equipment, as well as lead to injuries.
In order to ensure that your torque wrench is calibrated correctly, you must follow the manufacturer’s instructions for calibrating your specific tool. The procedure typically involves using a known weight or tension value and comparing it to the torque wrench reading. If the readings match within an acceptable tolerance level, then the torque wrench is considered accurate.
Tools for Checking Torque Wrench Calibration:
1) Torque Analyzer
This electronic instrument is simple to use. It includes a display that tells the user if the wrench is properly calibrated. Furthermore, some analyzer units allow you to link with various external torque sensors and utilize operating settings that let you conduct tests on different tools. If using a smartphone is easy for you, this analyzing tool will feel similar.
Some testers or analyzers do not need to be placed on a flat surface. Others, such as pneumatic wrenches and air hammers, should be secured to a solid foundation like a workbench.
They work in such a way [2]:
- The menu screen will offer choices such as Quick Test, Units, Mode, Setup, and Filter;
- Begin by putting torque on the input of the analyzer;
- The torque indicator is attached to an offset arm and has a lever that operates a gearbox. When it is started, the pointer rotates away from zero, traveling to its highest point;
- When you use the wrench, note that the reading on the tester is compared to it;
- To check if the torque wrench needs to be calibrated, simply follow the directions on the device;
- The analyzer will output a result indicating whether calibration is required. These readings can also be sent to your computer in a matter of seconds;
- When the torque wrench test is complete, remove the indicator from its mounting bracket and store it in a safe and protected location;
Another benefit of these testers is that they are portable enough to be used on construction sites or other locations where precision tools may not be available for calibration purposes. They can also be used by anyone with basic knowledge about how to use them without having any technical expertise. It will help you avoid unnecessary costs when hiring someone else to do this job instead.
2) Torque Loading Bench
This calibration tool is used to apply a known load or tension to the wrench. It can be helpful in verifying the accuracy of torque wrenches that have dial indicators. The bench allows you to set the desired load and then tighten the fastener until it reaches this value. This will help ensure that your torque wrench is reading within an acceptable tolerance level.
The loading bench should be calibrated annually, as well as anytime its accuracy is called into question. It must also be recalibrated if it sustains any damage that could affect its performance.
To use the loading bench, you first need to attach it to a workbench or other sturdy surface. Then, place the torque wrench on top of the bench and attach the indicator to the screw or bolt you want to test. Next, set your desired load and tighten the fastener until it reaches this value. The reading on your gauge should be within an acceptable margin of error for its calibration interval.
The main advantage is that they allow you to easily verify whether a wrench needs recalibration without having any technical expertise about how these devices work. You can also use them at home if necessary because they’re small enough not to take up much space in most garages or workshops but big enough so that anyone with basic mechanical skills can figure out what’s going wrong when something goes awry during testing procedures.
3) Digital Torque Adapter
This handheld device can be helpful in verifying the accuracy of torque wrenches. It works by measuring the amount of twist or rotational force applied to it and then translating this value into pounds-foot or Newton-meters. This information can then be used to determine if the wrench is within calibration tolerances.
The digital torque adapter should be calibrated every time you use it, as well as any time its accuracy is called into question. It must also be recalibrated if it sustains any damage that could affect its performance.
To use the digital torque adapter, first, make sure that the batteries are inserted correctly and that there is no debris blocking the sensor head.
Next, attach it to the end of the torque wrench and zero out the reading by pressing down on its “zero” button until it reads zero. Then, apply force to the wrench in order to make sure that everything is working properly before calibrating your device with this method.
4) DIY Bench Tester
This homemade device can be used to check the accuracy of torque wrenches. It consists of two pieces: a base plate and an indicator armature.
The base plate should be made from wood or plastic, while the indicator armature is typically constructed out of metal such as aluminum or steel.
Some DIY benches have small holes drilled into them so as to allow for easy attachment/detachment when testing different types/sizes of wrenches. Others do not require any modifications whatsoever (but may still come with pre-drilled mounting points).
The bench itself needs only one screw holding it together at its center point which will act both as an anchor for attaching other components like indicators arms) and also serve to keep everything level while calibrating a device by providing some friction when pushing down on it (such as with a pencil tip or eraser end).
To use the DIY bench, make sure that everything is level and secure before attaching any parts to it.
Next, attach your indicator armature so that its center point sits directly over where you would like your calibration marks to go.
How to Calibrate a Torque Wrench:
- First, make sure that the wrench is clean and free of any debris or lubricants [3];
- Then, set the desired torque value on the wrench by rotating the barrel until it clicks into place against one of the preset values;
- Apply this force to the fastener you want to test; if using a digital torque adapter, be sure to zero out the reading before doing so;
- If using a homemade bench tester, use a screwdriver or some other object with a flat surface to push down on the indicator armature until it touches (or nearly touches) whatever you’re measuring against (a calibrated level or ruler works well for this);
- Take note of how many full rotations it took to achieve your target value; divide this number by the number of rotations that were required to achieve your torque wrench’s “zero” setting and this will give you the percentage of accuracy;
- If the wrench is not within calibration tolerances, then adjustments must be made until it falls within the desired range; consult your manufacturer’s instructions for more information on how to do this;
FAQ
1. How do you know if a torque wrench is accurate?
Hang the rope’s loop end on your torque wrench where you made your mark in step one (e.g. 15 inches) to suspend the weight. If your torque wrench clicked once, the weight was added, and if it did not click, your torque wrench is accurate already [4].
2. How do you check torque wrenches?
There are several ways to check torque wrenches. One way is to use a weight, as we just described. Another way is to use a known torque value and a calibrated device like a micrometer.
You can also use the “jiggle test” which is done by applying pressure in opposite directions on either side of the wrench handle while tightening or loosening the bolt. If there is no movement in the handle, the wrench is tight; if there is movement in the handle, then it isn’t tight enough.
Finally, you can try using your torque wrench on another bolt of similar size with a similar thread pitch. This will help you determine how much adjustment your torque wrench may need.
3. How do you calibrate a torque wrench?
Here is the process of calibrating a torque wrench.
A torque wrench will help you to tighten nuts and bolts at specific angles.
What’s more, it helps in performing repairs on your car or bike with precision and ease. But over time, it starts losing its accuracy levels due to wear-and-tear or other reasons. So, you have to calibrate your torque wrenches regularly so that they can give accurate readings when needed.
Here are the steps for calibration [5]:
1) You need to mark the torque wrench at 30 foot-pounds
This is to make sure that the tool has a zero reading when you are not applying any pressure on it. So, take your torque wrench and place it in a vice grip or anything similar so as to hold its handle firmly against its body.
Now, tighten this using an adjustable wrench until you see that the scale reads 30 foot-pounds and there’s some tension on the spring of your device. Make use of both hands while doing this job so that you do not exert too much force accidentally; otherwise, the accuracy level will be compromised even after calibration. Take away your adjustable wrench now.
2) It’s time to check whether you have done a good job
Now, take your torque wrench and place its head against the vice grip or anything similar that you used in step #01 above. Apply some force at 30 foot-pounds to see if there is any back pressure on it when it reaches this level. If you feel such a thing, then turn the handle of your torque wrench clockwise until there is no more tension on the spring.
3) You need to repeat steps again now but with an increased value of 50 foot-pounds this time instead of 30 foot-pounds like before
Make sure that everything stays intact while doing this task otherwise; all your efforts will go down the drain. Apply 50 foot-pound force on the torque wrench and check if there is any back pressure at this level.
4) Finally, calibrate your torque wrench with a value of 100 foot-pounds by previous steps once again
This will be its new calibration limit so make sure that you remember it.
4. Do torque wrenches go bad?
Yes, torque wrenches can go bad. Over time and with use, the internal components of a torque wrench can wear out and affect its accuracy. To ensure your torque wrench is still accurate, it’s important to test it periodically. There are several ways to do this, but one easy way is to use a known weight and check the reading on the torque wrench.
5. How often do you need to calibrate a torque wrench?
In a nutshell, it’s common to calibrate your torque wrench every 5,000 cycles or 12 months, whichever comes first [6].
6. How much does it cost to calibrate a torque wrench?
The cost to calibrate a torque wrench varies depending on the calibration service you use. Generally, it costs between $50 and $100.
7. What is the most accurate torque wrench?
The Tekton ½-inch drive torque wrench is one of the most popular and trustworthy tools, thanks to its blend of usefulness, value, and positive user feedback.
This clicking-type torque wrench can properly tighten fasteners up to 150 lb-ft of torque [7].
8. What can I use if I don’t have a torque wrench?
Try testing your torque wrench with a known weight. If it’s not accurate, you can try tightening the fastener by hand as much as possible and then use an adjustable wrench to give it one more turn.
Useful Video: Calibrate Torque Wrench Without Any Special Tools
References:
- https://amgboltingsolutions.com/testing-a-torque-wrench-how-to-calibrate-a-torque-wrench
- https://blog.mountztorque.com/how-to-check-torque-wrench-calibration-an-illustrated-guide-slp
- https://www.wikihow.com/Calibrate-a-Torque-Wrench
- https://www.equipmentworld.com/maintenance/maintenance/article/14970962/how-to-calibrate-a-torque-wrench-stepbystep
- https://www.futek.com/applications/How-to-Calibrate-a-Torque-Wrench
- https://calibrationselect.co.uk/torque/how-often-calibrate-torque-wrench
- https://www.cnet.com/roadshow/news/best-torque-wrench