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Engine Building Fundamentals: How to Use a Torque Wrench

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How to Use a Torque Wrench


00:00 - Using a torque wrench isn't exactly complex, but there are still a couple of tips and tricks that you need to understand to make sure that you're accurately torquing up your fasteners.
00:11 In this video, we're going to look at how to use both a digital as well as a conventional torque wrench.
00:17 We'll start by looking at this snap-on digital torque wrench.
00:21 Now this particular example is a half inch torque wrench, and that relates to the size of the drive, and so also define what size sockets we're able to use.
00:31 This particular torque wrench is able to measure torques between 25 and 250 foot pound, and that's a relatively common range for the majority of our engine building requirements.
00:45 Now if we turn the torque wrench back over, we have a screen and some buttons where we can set our torque.
00:52 We can start by simply turning the unit on and what we'll do is cycle through the different units that it's able to measure.
01:01 We can swap between these by pressing the units button or U.
01:05 At the moment we're in newton metres.
01:07 We can also measure in foot pounds and inch pounds, and this particular torque wrench also has the ability to measure torque angle.
01:16 For this particular example, we're going to be torquing a fastener up to 45 newton metres, so I can just use the up and down arrows until I reach my desired set point, 45 newton metres.
01:30 Now we can actually go and tighten the fastener.
01:33 Now we're going to look at a more conventional torque wrench.
01:36 Again, this is a half inch torque wrench, although this particular wrench is rated between 20 and 150 foot pound, so it's not obviously going to be useful with very high torque ratings.
01:50 With these particular types of torque wrench, we have a window visible where we can see the torque setting.
01:57 What we want to do is pull the end of the torque wrench out, and that unlocks the adjuster so we can physically change the torque setting.
02:04 We can change the torque setting by simply rotating the handle until we reach our desired set point, Again, this time I'm going to go to 45 newton metres, and what we want to do is just bring it up to the 40 newton metre mark, and that will happen when the red line crosses our 40 newton metre scale, and we can see we also have a scale here on the handle.
02:29 In order to get to 45 newton metres, what we want to do is rotate until we end up on the 40 and then also the five.
02:39 Once we have achieved our desired torque setting, we can push the end of the handle in and that will lock the torque wrench so we won't accidentally adjust it.
02:48 For this demonstration, I'm going to be torquing up a single fastener on a main bearing cap on this engine block.
02:55 Before we get started, we need to make sure that the fastener is lubricated, and you want to use the correct lubrication here as per the manufacturer's specifications.
03:05 In our case we're using plain engine oil.
03:08 I'm using a 14 mil multi-hex socket, which just slips nicely over the top of that fastener.
03:14 To use the torque wrench, I use my right hand on the torque wrench itself, and I'm using my left hand to support the head of the torque wrench.
03:24 Particularly when you're tightening very high torque rated fasteners, you may also find it's useful to support your engine stand with your foot, and that just simply prevents the engine stand from rotating when you start applying high torque levels.
03:40 Now that we're ready to tighten the fastener, all I want to do is smoothly apply force and turn the fastener, and while I'm doing this, I can see the torque rating increase, or the torque value increase in the window on the torque wrench.
03:55 I just want to come up smoothly on my torque setting.
03:58 With the snap-on digital torque wrench we're using here, this gives us two signals when we've reached our torque rating.
04:05 It will give an audible beep which we heard there.
04:08 It also vibrates through the handle of the torque wrench, and this allows us to feel that we've reached out torque setting, even if we're operating in a noisy environment.
04:18 The other thing the torque wrench will show is the peak torque value that was achieved, so we can easily compare this to our specific torque rating, and if we haven't quite got to our torque rating, we can simply go a little bit further to get where we need to be.
04:35 Now we're going to look at our conventional torque wrench.
04:37 And really the technique is no different.
04:40 We're going to fit the torque wrench to our fastener.
04:43 Again I'm supporting the head of the torque wrench with my left hand, and my right hand is centred on the handle of the torque wrench.
04:50 I'm just going to smoothly increase the force on the fastener until I reach my set point.
04:59 With this particular torque wrench, you can hear that it audibly clicks when we get to our set point, and this is what lets us know that we've reached the correct torque setting.
05:10 Another aspect with any type of torque wrench that is important to understand is that they will require calibration from time to time.
05:20 Particularly with any torque wrench that you're using on very critical fasteners, it's worth having your torque wrench calibrated yearly or even more often, depending how often you're using it.
05:32 As well as that to make sure that your torque wrench stays as accurate as possible, with this style of mechanical torque wrenches or conventional torque wrenches, when we're finished using the torque wrench it's a good idea to always back off the tension on the torque wrench so that it's stored with no tension applied.

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