If you’ve ever over torqued a fastener and broke a part while using a torque wrench, you might be wondering how to calibrate a torque wrench. Are the torque wrenches you are currently using accurate? I recenly had a situatioin where I overfastened a bolt and broke a part and I decided to calibrate my torque wrenches. Here is the video.
Hey everybody, Steve here and today I want to talk about torque wrenches. And the reason why I want to talk about torque wrenches is because I recently had a torque wrench which actually went sailing across the room and broke but that’s another story for another time. Anyhow, that torque wrench was not calibrated correctly and I over torqued a part on the car and strip the threads, had to retap it and put a bigger bolt in it and anyhow it was a big pain. So, I was thinking to myself, well, I’ve got all these torque wrenches kind of all by the same manufacturer and I’m wondering are the rest of these things out of calibration as well? So what I want to do is I want to calibrate them and I’m gonna go ahead and just take video of it here so that for those of you who ever wanted to do this and weren’t sure exactly what the procedure was I’m going to go ahead and show you. Now, I am warning you it is going to be a little bit of math here but I’m not that good at math so I’m gonna make the math as easy as humanly possible. Some of the things you might need to do this is you’re going to be torque wrench, a measuring device, this measures up to a foot. Just in case I have to measure over a foot I’ve got that guy. I’ve got some weights, 20 pounds worth of weights, I’ve got some tape and I’ve got a bench vise as well. I think that’s pretty much everything. So, this really isn’t that hard. I’m gonna go ahead and I’m just gonna start with this guy right here.
Alright, so what I’m going to do is I’m going to measure from the center point of the shaft down the shaft. And in this particular case, I’m going to pick a nice well-rounded number, I’m going to pick 12 and 12 takes me right about to where it says Newton, above the Newton. So, where Newton is actually showing. So, what I’m gonna do is I’m gonna grab this guy there. Alright, so there’s that. So essentially what I’ve got here is I’ve got 12 inches and I’ve got 20 pounds. So, what I’m gonna do is I’m going to take my trusty calculator out and I’m gonna go 12 times 20 which equals 240. That is 240-inch pounds. This particular torque wrench is a foot pounds torque wrench, it has a range of let’s see here 10 to 150-foot pounds, so that’s 240-inch pounds. So, if I take my 240-inch pounds and I divide that by 12 I get 20-foot pounds. So, what I want to do is I want to take this guy and I want to set it to 20. So, let’s see here. There’s 10, I don’t know whether you can see this or not but there’s 10 and if I go all the way back to zero I am at 20. So, there is 20-foot pounds. I’m gonna tighten this guy up- 20-foot pounds. What I’m gonna do is I’m gonna take my torque wrench and I’m gonna put him in the vise and clamp him down. I’m obviously not going to clamp too hard. Got it nice and horizontal, nice and horizontal. So, if this is accurate, when I take my 20 pounds and I put it 12 inches from the base it should click. So, let’s see what we got. There it is, no click. So, let’s see if it’s further downstream, no click; further downstream, there it is there’s a click right there. So, we’re not too far off but we’re certainly not there. Remeasure back here, nothing. So, what I want to do is if it doesn’t click, if it doesn’t click I am going to tighten the spring. So, I’m going to take my little Allen key and I’ll put it in here and what do I want to do? How about a quarter of a turn? I’m just gonna go one quarter of a turn.
Alright, so now I’m going to take my weights and I’m going to hang it right here right at our point and it clicked. But did I go too far? To see if I went too far I’m gonna move it a little closer in and it didn’t click. Let me just retest it, it didn’t click. Let me come back out right there, pretty darn close. I might have gone a tick too far but there’s our measurement right there. Take it in a little bit, it’s clicking but I might want to just take this back out, I mean, just ever so slightly, just a tiny little turn and I should be able to hear a click there and I should not be able to hear click here and there it is.
So, what I’ve done is I’ve properly calibrated my torque wrench. So, I am going to take this guy and I’m going to put him away. So essentially what I want to do is just take the pressure off, take them back down to zero and go ahead and store him. He’s good to go.
Alright, so I’m going to use the exact same procedure on the rest of my torque wrenches. I’ll be able to use inch pounds for these guys. I am going to use foot pounds for this guy and I think at the end of the day they’re probably not perfect but I know that at least they’re in the ballpark and I’ll be able to do a little bit more relaxing next time I go to torque on something.
So anyhow, I’m Steve, hope you learned something. If you did, please like, comment and subscribe. I’ve got lots and lots more videos to come so be sure to hit that little bell so that you get instant notifications every time I got a new video coming out. Tons and tons more to come. Thanks so much.