As an amazon associate, I earn affiliate commissions from qualifying purchases.
Torque wrenches are the magic tools that have graced our toolbox with their presence. If you own a car, you must own a set. Even the professionals have to rely heavily on these. Torque wrenches are precision tools. But their performance depends largely on the person wielding it.
If you know your way around a torque wrench, then congratulations! You can change the wretched tire that’s wreaking havoc in the middle of your drive when there’s no car-gurus flying around. But you also need to know how to set a torque wrench in inch-pounds, the smaller unit.
Precision is absolutely crucial here. If you turn it even an inch more or less, that may be the cause of a horrific accident.
But first, let me tell you what ‘torque’ is. It’s the twisting force you apply on an object to rotate it, in this case, a nut or a screw. Torque is calculated by multiplying the linear force you apply with your hand in the axis of rotation and the distance between the bolt and your hands.
Normally torque is calculated in three units – newton-meters in the metric system, but the most commonly used units are foot-pound and inch-pounds. Fastening a small bolt requires more careful handling and precision, so people normally prefer an inch-pound wrench, but you might not have one lying around always.
A foot-pound torque wrench with smaller drive heads will get the job done. But you need to mind the conversion factor if the specs are given in inch-pounds. And if you have a digital torque wrench, you can switch units as you please. Just go to the menu, select the units with the navigation buttons, adjust the torque, and voila!
I’m going to focus on beam type and click type torque wrenches that require manual adjustments. If you’re stuck with a foot-pound torque wrench, you just need to do the math yourself. A foot is equal to 12 inches, and an inch is 1/12th of a foot conversely. So, what if you need to adjust the foot-pound wrench to 144 in-lb?
That’ll mean you have to set the value to 12 foot-pounds since you get 12 by dividing 144 with 12. In the click-type torque wrench (the most common type), there are two scales – one on its body and the other on its handle. The marks on the body-scale have 10 pounds in between the marks.
I Have the Value. How to Set It?
Let’s get back to the foot-pound wrench. To set it, we need to unlock the handle. There’s a screw at the end of the handle, pull it out and rotate it counter-clockwise. This’ll loosen up the handle. The first thing you got to do is to unwind the handle to the mark ‘0’. Why?
All these adjustments and collaboration applies to a spring inside the handle, which is under immense pressure all the time. Unwinding the handle to zero eases up the load on the poor guy. This is for preserving the longevity of the torque wrench you love so much. If the spring breaks, it’s all over for the master tool.
After unwinding the handle, rewind it back to 10. Mind you, we need to get to our target: 12 foot-pounds. To get two more, you need to adjust the scale on the handle. Find the ‘2’ mark and align it with the big scale. So, now you have 12 foot-pounds, ergo, 144 inch-pounds. All you have to do is lock the screw back in.
While you are doing that, keep an eye on the handle so that it doesn’t budge while you’re locking it back in. That’ll change the calibration value. Next, equip the wrench with a suitable head drive. Lock it in place and twist it. You’ll know that you’ve reached the mark when you hear or feel the click.
Calibrating the Beam Type
Things are a bit more complicated with a beam-type torque wrench. You won’t be able to calibrate it. The dial of the wrench will show you how much torque you’ve applied once you start twisting it. So, you have to keep your eyes on the beam at all times like your life depends on it!
However, you can make things easier for yourself. After calculating the inch-pound value, you can place a marker on the beam. I used to put a thin tape on the scale. This let me know when I had to stop to get my desired value. Beam type is the most pristine type of torque wrenches, in my opinion.
Digital Wrenches: Convenience at a Cost
If you really hate doing math and don’t want to do elementary calculations before doing the hard work, let the cash flow and get a digital torque wrench! After you’ve reached the calibrated value, you’ll hear an alarm or buzzer. Then you can stop.
Torque wrenches are a reliable piece of equipment, but you need to set the value precisely before you can bet your life on it. Knowing how to set a torque wrench in inch-pounds can save you a ton of hassle, especially if you don’t have an inch-pound wrench.
This article focused on giving you the gist of it, but don’t use it if you don’t have the practical know-how. So, spend a lot of time practicing before you swing it around a rigid tire-bolt.