If this video helped you, please consider clicking on the THANKS button above to support my channel 🙌 PLEASE NOTE: there is an editing mistake in this video - ALWAYS set the specified torque by twisting the handle BEFORE measuring the length from the head. Otherwise your measurement will be wrong :) thanks!
@@ClaudeSac Tbh hitting the thanks button wouldn't have occurred to me if he hadn't mentioned it - and I feel indebted for this invaluable and money-saving advice so it meant I could show my appreciation in some small way! With 5.7k likes, a small percentage of donations would really add up and encourage more advice like this. A few quid is a lot less than paying someone for the info, or recalibrating or replacing a tool!
Nice tip, I will be re-calibrating both of my wrenches. One tip I was given more years ago than I care to admit was to turn your torque wrench back to zero after use, relieving the tension on the spring. Cheers, Geoff
At work, we had our torque wrenches calibrated yearly. As an experiment, I bought a really cheap one and left it wound right up for three years, it passed calibration.
@@paulhawkins6415 "experts" say "don't keep your magazines loaded with ammo, as it will weaken the spring". Yet militaries around the world store full loaded magazines for who knows how long.
My magazine spring began to misfeed my H&K USP .45 in less than a year of being my always loaded bedside gun. Changed the spring, problem gone. @@savage22bolt32
Brilliant. I’ve got three torque wrenches I’ve had for years. Always take care of my tools but wondered if they had started to lie to me over time. Never even knew about the calibration bolt. Perhaps I should RTFM! Thanks & subscribed.
I found that the non-knurled ring is exactly the calibration point on three various wrenches. Checked by a weighed bucked of sand at home, then on a NIST-traceable calibrator at work.
A metroligy lab would calibrate that wrench in 2 or 3 different spectrums of the scale. Lower end, middle, and upper end of the scale. If it is continously used at a specific setting, they may also include that in their calibration. Note any equipment used to set/measure the calibration must also be calibrated. In this case the tape measure and weight set. If the tool was found to be out of calibration, in this case +/- 4%, any item torqued with it after the previous calibration would need to be recalled. With that said, prior to calibration, the current torque should be measured prior to any adjustments. Also note that the bolt that was torqued also had a +/- tolerance and would be taked into the account of any recall. The frequency of calibration would be based on how often the the tool is used. Ben Retired 30 year 3M Quality Technician
An Allen key??? Have to check - YES, my wrenches do have those. Always wondered how calibration works - and, yes, I am blushing. Greatly. Many thanks mate, sooo valuable info this.
I tried both ways (i.e., testing and doing the math measuring the distance at the minimum setting and at a selected torque setting prior to adding the weight) and the first/original explanation seems more accurate. If you set the torque setting before measuring, the math equation simply doesn't work. In short, in my view, the original comment made in the video was and is correct. Either way, you have superb communication skills and a equally great demeanor. You'd be an excellent Professor.
To calibrate a torque wrench, you have to verify the whole range, not just a point or two. You have to check the full scale, the minimum indication and several points in between. Then you may have to make a compromise to bring the whole scale in tolerance. You can't do it this way.The torque wrench you show is a cheap one. The precision of these wrenches is not even along the range, especially at the low end. I have such a cheap torque wrench and I calibrated it professionally (I work in a lab and I do calibrations for living). The range was 60-200 Nm, the first portion of 60-100 was useless( +20% error), but the rest 100-200Nm I was able to tune it bellow 1%.Therefore I use it only for torques above 100 Nm. My advice is to buy a $50-100 device. A relatively good quality torque wrench has specified in the manual, the length of the arm, so you can calculate the torque if you use an extension, If you're a mechanic you really don't need a $1000 torque wrench, you work in a shop not in a lab. Anyways, if you want to play with it, why not. There are professional calibration labs out there and they do it for a reasonable price and also you get a AALA recognized certificate of calibration.
You forgot to reposition your weight point after changing the setting on the wrench, if you change the setting, your weight point moves with the handle since the handle extends/retracts so you need to get your measuring tape back out and look where your weight position is now.
Referring to the imperial/ftlb wrench. If you use it an inch further from the head than where you measure that would be 12". In that case there would be no calculation needed. Xlbs/12x12 is a wash.
you moved where the original 20 cm mark was when you adjusted the wrench. so you need to hang from the same 20 cm not the same spot on the moving handle
Hi, I wanted to do two tests after calibrating it: my key is small, 5 -25 nm, I set a weight of 2.6 kg at 20 cm that clicked at 5 nm and calibrate it. I wanted to do a new test with 4.6 kg at 20 cm result 9.1 nm but it doesn't click. I calibrate at 9.1 nm by loosening the spring tension but when I try the 5 nm again with the 2.6 kg from before it clicks much sooner. I recorded from the bottom dial. I don't have the same calibration for the various measurements.
Did anybody else catch the error? You found a location to hang the weight before adjusting the handle, thus making the adjusted point different than the measured point. Repeat the test but measure the hanging position after making the handle adjustment.
It makes a marginal difference, but we’ll within acceptable tolerances. You can use a fishing scale and work horizontally which is what I have started doing for ease.
Buy a $50 digital torque wrench adapter. They're far more accurate than the most expensive click type torque wrenches. It's too easy to make a mistake using this method for a lot of people. You can use the digital adapter directly or use it to calibrate your click wrenches. Or both. The click type or better for many places that are hard to reach with a bulky adapter.
I had 7 torque wrenches to calibrate. I bought a digital torque adapter to calibrate them. Most were fine. But a few were off. I was able to calibrate all but one of them. The reading on one of them is all over the place. It is not consistent at all. Does this mean that this torque wrench is toast and it can no longer be calibrated?
I'm not knocking this method at all. It's handy to know. But I'm curious how you set your non-digital torque wrench to such a precise figure as 12,88 Nm [an accuracy of a hundredth of a Newton Metre!] using only the engraved scale on the handle? I have a couple of troque wrenches bought 2nd hand off eBay, years ago, which have never been calibrated, since I've had them. I'd like to calibrate them, just for curiosity's sake, if nothing else. But I also think that most of us [who I presume are using torque wrenches to tinker on our cars] can get a bit too OCD about these things. Unless you're working for NASA, I reckon "close enough is good enough" for the vast majority of fasteners we come across --with the possible exception of cylinder head bolts. [Ducks head beneath parapet]
I would like to buy a 10-60Nm I can't find a direct link to buy the Kincrome with prices etc.... if you have it I would be very grateful if you would post it. Thank you very much in advance @@VintageEngineRepairs
This is a way to service your tools without the need for expensive tools or the need to buy anything. It gets you more than accurate enough for what we need!
A good post and usefull vid .👍 Most cheap high street wrenches are way off and need calibrating. I Used to calibrate equipment as a tech support engineer both eletrical from fluke meters to torque wrenches Ultra light 6ft lbs too 500ft lb long bar. Good advice for a rough home setting. I'll just add to get it spot on you ideally need to check the lowest, the mid & the highest settings as the spring tension accuracy can vary hugely and may show that the tool is no longer accurate on all settings. Most common reason is because people dont reset the wrench back to its lowest setting after use and just leave it for months with the internal spring under constant load.
You should measure the distance from the drive (where you hang your rope) AFTER you set the wrench to the appropriate weight because the handle moves in slightly toward the drive as you turn it. Also, make sure the wrench is perfectly level. Good tips, though. Thanks for sharing
These clicker type wrenches are typically calibrated for the force applied exactly at the middle of the grip (and it does matter, there are a few videos explaining and clearly demonstrating this), therefore that should be the point you hang your weights from and measure the distance to. Ideally, one should test different hanging positions on the handle with different weights at both ends of the wrench's torque range, find the position that gives the most accurate results throughout the torque range and then only apply force at that exact position during normal use. Whether it's going to be the middle of the handle or closer to either end of it really depends on each specific wrench model.
Great video. I'm going to try this out myself. One note: I think it is important for the torque wrench handle to be parallel to the ground. If it isn't parallel (or as nearly so as possible) then the effective length is different from the measured length thanks to vector trigonometry.
Yes sir you’re spot on! I think it’s important to be as accurate as we can, but also remember that even if things aren’t precision perfect - it will still be more than good enough for what we do :) you won’t snap bolts being a bit over nor will it cause an engine to fail being a bit under the specified torque. Thanks for sharing!
@@VintageEngineRepairs Just as a follow up, if you're within 10˚ of horizontal you'll be within 2% of accuracy, which is equivalent to +/- 4mm on your length measurement. Given your string is about 4mm in diameter, that's plenty of precision. If you get out to 20˚ you're still within 7% of the calculated value, but it starts to rapidly fall off in accuracy after that.
@@daveatutubeAs the purpose is to calibrate the torque wrench, you want to do what you can to achieve max accuracy, and that does not involve having the handle at an angle.
@@VintageEngineRepairs You did not mention it, but did you weigh the rope with the weights? For that 1 or 2 % accuracy, the rope may make a difference. Not moaning, just checking/mentioning. Also, could we all say pound-foot, like Newton-meter? That's moaning ;)
This is the best DIY demo I've found. The process is not that complicated, although for accuracy the right angle distance and mass need to be accurate. I've often wondered how much ambient temperature affects this clicker style of wrench. In the end, most of the time a variance of 5% is fine. Often it is a comparative tool, so even if it is out a little, all the bolts will have the same torque. These days we tend to go overboard with torque, although the margin for error in aluminum housings can be small.
Thanks for watching :) I agree, for what we all do 5% even 10% is not a problem. Heck you could be even further out and not have any issues. If it was on a a spaceship then it’s a different ball game. This gets you very close, easy to do at home and will be far more accurate than doing it by hand :) thanks for watching!
I agree that this is a clever way for diy calibration. Although not complete. Even though the style of torque wrench you show here is common, there are a lot of different ones. And the method of adjustment also differs. Some do have the screw you show now, but also a lock screw for instance. A lot of professional wrenches also feature an adjustable scale. Typically you adjust the screw you show in the video to set max torque, and adjust the scale for minium torque. Most cheaper wrenches have a fixed scale and I would recommend calibrating for the range you use, as it will be hard to get it right all along the scale. Most professional torque wrenches are supposed to be within a 3% margin along the full scale. Typical calibration is done at 0% 60% and 100% force. It will be hard to get it to within this spec with this diy solution. But it's definitely better than not checking it at all. The 3% margin is also ludicrous if you ask me, how you hold the wrench, how you apply force, is your bolt dry or lubed, etc will have more effect on the end result the a bit bigger margin on your wrench. Bear in mind that the electronic force gauges might also not be accurate. Especially cheap models can have quite some deviation. So you might want to check the force gauge with this method before using it to calibrate. In short, good method for approximate calibration with little expense. But not suitable for critical work. Just my 2 cents as someone in the tool business, including calibrations.
The wrench handle should be horizontal; maybe it's the camera angle that makes it look like it's pointed down, which would make it require a higher torque to click off.
One thing not accounted for with this method is the weight of the handle, which is small but not zero. In the big picture it's likely negligible. I suppose one could measure this with a simple experiment. Suspend the wrench with a string looped around the center of the head, then support the handle end with a scale. Multiply the measured scale weight by the right angle distance from scale contact point to string, and you've got baseline torque with no extra weight added.
Yeah I agree with you, it’s negligible, as mentioned before, for what we do, it’s not going to make a difference. Most torque wrenches come with, from memory, +/- 10% accuracy. Thanks for watching and commenting, it’s always good to hear other people’s opinions and ideas :)
Ah, but then you'd have to add or subtract the weight of the handle depending on whether you're pushing it up or pulling it down when you're actually using it. If the bolt is vertical and the handle is rotating horizontally then no correction would be needed.
@rtg8point858 for the imperial the math is the weight ÷12 × the distance along the torque wrench.. if you go with 12 inches, the ÷ 12 × 12 nullifies itself, so the result is whatever weight you choose, that's what you set your torque wrench to.. no math involved at that point. Hope that explained it for you 😁👍🏻
Good tip! You could also extend the handle with a pipe, or make your own tool to hang those weights at specific distances every time you do this. Ie. a two foot pipe with notches for the string at 12 and 18 inches, choose your weights according to the specs on the wrench. Super simple calibration every time. You also don´t need so much weight if you extend the leverage, so that might be a thing too.
Very cool, Tom! I knew a specific torque was dependant on weight and distance, so your procedure is brilliant. Those two figures and the conversions are all that's needed. Way to go!
Minimum spec on my Torque Wrench was 20 FT Pounds. I didn't do much math and still calibrated it. I though to myself "Foot, pound" Therefor 1 Foot away from the head should required 20pounds of load is what is needed to click it at the 20Foot Pound setting. So i filled up a bucket with 20 pounds worth of water and i was able to perfectly calibrate it. *I was able to verify this theorie with a new one and it clicked right when i was laying down the handle of the bucket on it.
I dont want to explain the reason, but ... ... always calibrate with the force of the weight where the manufacturer marked ist at the handle. (If you can find a mark = It is the middle of the area where your hand will be !) (You see it here in the video) If you choose an other point of the force from the weight = Calibration is wrong. Additional information = Please no discussion ! There is a reason why simply choose a nice distance from the middle of the squere Socket adapter to a nice distance for an easy calculation ... ... will result a wrong calibration ! See other videos that explain the reason (=it is inside and we cant see it and our brain always refuse these reason. But it is true = middle of the grip zone where your hand will be (often good manufacturer mark these area). Discussion with these RU-vid channels (or a maufacturer or these mechanical torque wrench with the easy inside construction. Remember there are Split beam torque wrench (= I never ask one of these manufacturer or saw a calibration RU-vidvideo that explain these physical rules for calibration. But I bet force of the weight at the middle of the handle).
After you set the torque, you've moved the spot you measured to, so dont you have to re measure from the socket drive because the spot on the handle you choose is now half inch or so up the bar??????
Hey, yeah that’s right, I did as you said, but the video was made up of multiple segments and it should have been put in first. Set the handle adjustment, measure and then hang. Thanks for watching and commenting!
If I were doing this, I’d just choose one of those grooves in your handle and then always use that. Find a way to measure the “proof weight” and the length as accurately as you can. Still, at the end of the day, the mechanism is only so accurate. You may get it perfectly calibrated, but then repeat the same torque application ten times and still get 1-2% difference in applied torque. Also, it’ll probably be different along the range of torques. It’d be interesting to get a digital torque gauge and then measure a bunch of settings to see how the variation looked along the range. Also, if you use the setup like in the video, you’d need to account for the weight of the torque wrench in addition to the proof mass. 😜
when you turn the setting handle, you're shortening the length of the torque wrench - you need to compensate for that when positioning your string because the initial measure is now off - should reposition the string at the original measurement of 11" which would require confirming with your measure tape (would shift slightly towards the end of the wrench a bit). small detail.
I prefer using a small luggage or fish scale, cheap to buy and accurate enough for this. Then just keep it at the measured distance on the wrench handle while pulling handle at 90 degree until it clicks...read max "weight" on the display. Adjust wrench calibration accordingly. This keeps the force at 90 degree to handle, no contribution from handle's own weight (as in this example with handle adding small amount to turning downward force applied). And no need for any calculations nor pre-weighed dead weights.
Awesome explanation! One of the best I've came across! 👏 About the point where to hang the weight, actually that bit without knurling is there to be the exact center of the handle 😉
Great video and so simple to do. I have been told by multiple tool shops that the smooth ring in the handle is the factory point where they test the torque wrench. Not sure if it is true but you might as well use it as a fixed point for future calibrations so you get the same point each time. You'll also notice that the ring is slightly closer the end of the grip, this is because when we pull on a handle at 90 degrees more of the force is concentrated towards the last 3 fingers (middle, ring and pinky) on our hand. This enables us to grip something very tightly while still being able to use our thumb and fore finger for other things. Try it out.
Yes, I noticed on your last click test by hand you probably without thinking positioned your hand right over where that band is on the handle. Cheers, great video
Yes, typically the handle is marked for this purpose. Not just for factory calibration, but also for recalibration. Different brands use different marks, but I would expect the clear ring to be the mark in this case.
When I was taught to use a torque wrench many year ago. We were told that the break in the knurling or the thin band of knurling was where your middle finger was supposed to be placed. The reason given was that this represented the calibrated distance from the drive head to achieve the most accurate torque. After watching your video, that make sense and would cause me to use the as a reference when calibrating. Either way, I really liked the video and thanks for the cool trick to add to my knowledge.
I don't think it matters where you hold it, the wrench still has the same accuracy just the force you need to apply will differ slightly but it will still click at the same nut torque force
@@stargazer7644 It does matter where you hold and calibrate the torque wrench. You are meant to apply the force at the groove that all of these torque wrenches have. They all have them for a reason. I know that may be unexpected because a torque is a torque after all, but these click-style torque wrenches complicate things somewhat. There are actually two torques in play here: one torque at the head of the torque wrench which is wrenching on some fastener, which is what we want to measure, and another torque at the "elbow" between the head and the handle. The torque wrench actually measure the torque at the elbow, which is where the clicker is, and we use that to stand in for the torque at the head. That works fine if we calibrate things right to give us the right numbers. However, the calibration assumes a particular ratio between the handle length and head length. To gain an intuition for this, imagine a particular torque wrench that has a particular torque dialed in. In your imagination, apply a torque at the groove and make the wrench click. Now, leaving everything else exactly the same, modify the wrench to lengthen the head and shorten the handle, but let's leave the total length the same as before. Let's say the handle is now half as long as it was, which means that the elbow will now be approximately half way along the wrench. Now, apply the same torque as before. Will it click? No, it won't because the lever arm to the elbow is half as long as it was before. You will have to apply twice the force to make it click now. That shows that the ratio between the two lengths does matter. Going back to the original torque wrench now, if you apply the force at a different place, you will be changing the ratio.
@@stargazer7644 The force from your hand should be applied at the same point that the calibration force was applied. You might as well use the groove that is put there for that purpose in every single click-style torque wrench. I know what you are saying. A torque is a torque. But that doesn't apply to click-style torque wrenches, as I explained above, because the "elbow" point, where the clicker is, is not at the same place as the "socket" point. The actual measurement point (the "elbow") is not exactly at the same place as the intended torque application point (the "socket"). For other styles of torque wrench such as a digital one or a deflecting beam one, then yes, it wouldn't matter where you hold it because the measurement point (the transducer in the digital one for instance) is at exactly the same place as the socket.
A good video on the how to of DIY calibration however you missed out a couple of vital points which better indicate why calibration is necessary. 1. The first is that when measuring the weight of the weight(!) you are using it's essential this is done with a set of calibrated scales otherwise the error in weight measurement is likely to introduce as much variation into the calibration process as the torque wrench itself. Without this step, you are just as likely to end up adjusting a correctly calibrated torque wrench to read incorrectly as you are to correct an incorrectly reading wrench. 2. It's important to check the torque wrench at three positions, once at the low end of it's torque range, once at the upper end it's torque range and once in the middle. You will almost always be able to set it correctly at one positions but not always in all positions depending upon how the device has been cared for among other causes. Failure to be able to set correctly throughout the range indicates a deeper dive and possibly repairs to the torque wrench are required.
Interesting however, to be more precise, don't forget to remove the weight of the torque wrench at the level of the grip (or to take it into account when calculating the weight), because when the torque wrench is horizontal, its own weight contributes to the torque and it distorts the calibration ... it's not essential on 1/2" torque wrenches but much more on 1/4" PS: sorry for my poor level in English
Great video for the home DIYer. It is also important to remember that these torque wrenches are more applicable when you're working with multiple bolts that all need to be torqued the same. I.e. car wheel lugs, or a pump head flange, etc. For a single bolt, especially in a sensitive application, these torque wrenches only bring you within a ballpark spec and probably not the best tool to use. But this calibration method is simple, quick and yields acceptable results, so thanks very much for sharing.
Thanks for watching and sharing, it’s a great method to set and keep your torque wrenches accurate for what we use them for. It’s not perfect with the small variables, but it’s more than accurate enough and offers anyone the ability to maintain theirs without any money spent.
It’s actually quite hard to get it accurate with luggage scales as the dial keeps moving. Having a set weight is free and consistent. You can do though!
I see 2 major flaws in your method, 1st: when you twist the handle to adjust the torque setting, the spot you've chosen to hang the weight has moved, now closer to the drive than you've measured before. To mitigate this, choose a torque and adjust wrench beforehand then calculate and measure where to hang the weights along the handle. 2nd: when it clicks, the torque wrench isn't perfectly parallel to the ground, it has sagged, hence the force of the weights acting on it isn't perfectly perpendicular. To mitigate this, let the wrench rest higher so when you put on the weights, it will click at approximately parallel to the ground.
Just thought of my first torque wrench, it had a pointer and a scale on it, the pointer was a thin rod in parallel to the main wrench bar; the challenge was to try and read where the pointer was while exerting steady pressure on the wrench! Geoff
I imagine it will be more accurate at certain ranges. So maybe less accurate at 10Nm, but more accurate at 40Nm. So you could calibrate in the ranges that you use most often, or calibrate before use. Or test at all ranges and make a chart.
I made a torque wrench 45 years ago special for ali engine motorcycles, I calibrated it by hanging a bucket by the handle and pouring in measured quantity of water.
When I calibrate my cheap german premium torque wrench (ot the cheaper chinease one) ... Oh dear , oh dear ! Good calibration at the low value, but worse at the max value. Best idea calibrtion at the value inbetween. Because I often use torque values in the upper area = Calibration in these area. But shure a non free calibratio by a certifyed calibration laboraty with a certificate will be a good idea. I think US $ 60 to $ 70 in my country (year 2021).
I have three Capri Tools torque wrenches (31007, 31000, 31002). I've owned them for about 8 years, and while they see very gentle use, I would still like to be able to make calibration adjustments if necessary. However, there doesn't seem to be an access port for a calibration screw anywhere on the wrenches like yours have. Help?
Your still off cause when you adjusted the wrench to what it should be set at you're adjusting the length of the tool by screwing the handle in or out, then not measuring the distance to see where your rope needs to be placed after adjusting the length to set the torque.
I measure from a point 1ft from the square drive cos I use ft-lbs.....I use a fisherman's fish weighing tool....I have tested that its accurate. I have a few cheaper ebay type wrenches....I find all a few ft-lbs out....I check each time I use one....I dont use them very often.
Extremely well spoken and coherent video. You should be cloned and used to teach mathematics, physics, chemistry, and technical report writing throughout every single learning institution.
In my bus manual, they literally have you torque down lugs on the wheels by using a .5, 1 or 2m long lung wrench, and body weight. Its a Romanian truck from the communist era. When poverty makes you get creative.
Brilliant - at last i have found someone calibrating a smaller 3/8 drive torque wrench in metric newtons rather than lbs! And plain and simply explaining the formula! Brilliant job - thanks a lot
I forget my school knowledge aswell. Smily = My teacher hitnot my head at the table and told remeber these for a lot of years. BUT = always calibrate(with the force of the weight) where the manufacturer mark at the middle area where your hand push. You cant find a mark = Where your hand push , these area, in the middle. Yes = difficult but your calibration will be fine for your presicion you need. At the low value and the max torque value the inside spring is not perfect. Choose the torque between both extrem values. Or if you prefer a standart use value for your work = choose these value. Big problem = Find a weight (or some) and it must fit for your torque. You got a good precision libra for checking the weights ?
This is awesome!! I never thought of looking for this process and always though that because I’m a diyer I’ll just assume that my torque wrenches will be within the tolerance. Thanks for this nice visual explanation!
That's a good DIY method. It took me a while to get inch/pounds torque wrench set properly as it wasn't assembled right and had 'fallen apart' during shipping (it was a Stanly, sold for parts, surplus store had about 10 or more on display) At the time I had access to a Snap-On torque calibration - tester so accuracy was well within the +/- % specification. Vast majority of spring ('clicker') torque wrenches are only accurate at centre scale (+/- 2%) and are often 10% at maximum or minimum readings, even expensive ones.
This is a classic case of you don’t know, what you don’t know. What you are doing is NOT calibration. You are simply doing a single point operation check. Calibration is testing using certified weights and documented processes under controlled conditions. Many tools have both span and linearity adjustments which you are not even checking. The reason actual metrology (calibration) costs what it does is its precision and repeatability. You have neither. What you are demonstrating is like trying to do brain surgery which a crow bar and a hammer. Stop messing with things you don’t understand. If you suspect your torque tools accurately may be compromised, send it to the manufacturer or a accredited lab for recertification. BTW, I’m a 26 year calibration technician for NASA. I’ve tested a few torque tools.
Excellent vid. Comments were helpfull to. Woulda been nice if WW2 resulted in one UNIVERSAL system of measure. Germans:METRIC.☠️ Britts:IMPERIAL. Awfully sorry chaps but..🙉 Yanks:OURS👹 Canada? We seem to have gone officially with the Germans. Sort of. Haven't nailed down one official language. And I could've saved a LOT of $ on wrenches, sockets etc if we all just got along. SOCCER🇺🇸. FOOTBALL🇬🇧. 🙈
Send it in to have it properly calibrated. Lots of hack mechanics think torque specs don't matter much and then I hear, "I've done a 1000 cars and never had a problem..." Like how do you know? Do you keep a record of the car? Have gps trackers on the car? Call the customer every week to see how the car is doing? You have no clue what happens to the car after it leaves the shop. If you're that cheap that you don't want to have the torque wrench properly calibrated get a beam torque wrench. You never have to calibrate them, and they are far more accurate anyway than these other style. And these newer torque wrenches are only used because of ego, because people are too embarrassed to have a beam torque wrench in their toolbox and god forbid if anyone seem them using a beam torque wrench.
In case someone wonders how accurate this could be: take the equation, pluck in min and max values of the weight and length accuracy. Say, you think you can position the rope at 5mm accuracy, so take 195mm and 205mm for his example. How accurate is your scale? Take say, +10g and -10g and calculate. Now you end up with two numbers that are the min and max that you could be out, in this case 12.53 through 13.21 ... which is well within the common 2-4% range of tolerances by the manufacturer. Oh, for extra accuracy, take into account the local gravity which for my place would be 9.80665 instead of 9.81 ;)
There's a fundamental mistake made despite the correct idea - one should fix the wrench body instead of the socket place. This way you will be calibrating the torque applied to the nut/bolt instead of calibrating the effort you apply to wrench. Why? Because torque wrench is a torque-converting mechanism and you don't know the length and the angle of the leaver INSIDE of it (the tooth that slipps out of its lock and makes that characteristic click at the set torque). Wrench should click at a set torque irrelevant on where you hold it. If you'll hold the wrench closer to the socket you would have to apply greater torque to tighten the nut to the set value, than if you'll hold the wrench for its end. So, by putting the weight on the handle - you calibrate only the place on the handle where your torque will correspond to the weight - the actual torque applied to the nut will remain unkown. But if you'll fix in place tha handle and attach a leaver of known length to where the socket goes - you will calibrate the torque mechanism to specs - there's no other way to place the socket other than on the socket holding mechanism, thus you'll eliminate the large deviation in weight placement. So the correct procedure should be: 1.fix the wrench in place by its body; 2. find the strong, long enough (70-100cm), homogeneous leaver, measure its weight and length; 3. attach the leaver to the socket holding place; 4. place the reference weight (1kg or smth was in the video) to the MIDDLE of tge leaver 5. adjust the calibration screw so that wrench clicked at calculated torque. Your calculated torque will be (for metric system in Nm): 9.81 * 0.5 * leaver_length_in_meters* (ref_weight_in_kg + leaver_weight_in_kg).
Good information. Just a small reminder, in the English language a VISE is what you're using to hold your torque wrench. A VICE is immoral behavior. ;-)
If you wish to calibrate it really accurately to your personal usage. Adjust the weight to midrange first for say zero to 100 ft lbs. Set the TQW at 50 ft lbs. Then grip it as you by the knurled handle normally would use the wrench. Now mark the center of the wrench handle between your 2 middle fingers. (With a sharpie extend that line around the handle by using a strip of paper or tape). That will be your actual weight hanging line. Then measure that line to the center of the socket lug. Do your calculation as instructed in the video, prepare your weight and rope. Check and calibrate, set. Check again at same line at 100 ft lbs setting (at same line w/100 lbs of wt remeasure the handle and recalculate), repeat at 10-25 ft lbs. At that point it is customized to your grip also and will show you how off you really are at top and bottom of the wrench settings. If 100 ft lbs hanging does not quite click it (when calibrated perfectly tested at 50 ft lbs), but a tiny bit of downward pressure to that line with wt hanging clicks it...then calibration at 100 ft lbs usage can be assured by a double or triple to quad clicks at upper range usage. For lower range usage switch to an actual inch lb wrench and recalculate and calibrate that wrench also. (I have both and will always use the smaller wrench for smaller work). 20-25 ft lbs give or take. All of my automotive manual torque charts have been hand calculated and notated (converted from ft lbs to also include inch lbs for fast reference and work).
Clearly I'm on the very bottom of the gene pool since I don't understand how can you set the torque value, BEFORE you measure the length, considering that in the equation, you FIRST need to know the length to obtain the torque value that you have to dial in??? What am I missing???
Good video, takes the mystery out of calibrating torque wenches. I wonder if it would be more accurate to say you were mainly using the wrench for tightening oil pan bolt to 20 ft lbs then use a 20 lbs (2x10lb weights). So using the amt of weight that you generally used the wrench for.
Yes :) that’s exactly what I have done since this video. My 1/4” is set perfectly for about 8nm because that’s where it gets used most. The 3/8 gets set at 20ftlbs for the same reason :)
The band is the point at which the wrench is calibrated. Keep it simple, they should all have a band to work with. A big nut on the horizontal is actually better than a vice. The force of twisting a square cam in vice jaws is extreme. Should be able to break a large vice at higher settings. I've broken 2x 6" industrial in my time through mis use and abuse, they break with a seriously loud bang.
Well done Tom, I'd recommend everyone test their wrench at minimum, mid and maximum range. Let's face it, most of us won't have a bunch of torque wrenches where each has a range that overlaps the others in their kit by 50%, I know I can't afford that many. Whatever torque I need to apply, it will always only fit inside the range of one of my wrenches, that might be near the extremes of range. Excellent video, cheers.
Thanks for sharing. Great video! I was wondering would you not de-caliber the torque wrench if you first measure the length before setting up the torque value on the torque wrench? The length may change and therefore it may create inaccuracies, depending on the starting point. Also, would you not de-caliber the torque wrench if you start calibrating the tool first with a lower torque value, and then move higher values across the range? Will that not de-caliber previously calibrated setting you just did in the previous step? Cheers.
Great method! I think it should be underlined how accurately you should measure the distance. If you want to be even 4% accurate with the measurement, you cannot go "about 11 inch" or you'll be off by more than 4% for sure. It might be a good idea to use metal wire for hanging the weight to be sure you're applying it exactly correct position.
Honestly I would test it wherever your pinky finger will be. That will be where most of the pressure will be applied when pull torquing. Push torquing would be more in the middle I am guessing.
It's good to check that the wrench is not WILDLY out of adjustment. This is a good method. If by moving the rope only 5 mm up and down the handle changes the torque, one must then assume ANY force applied by the human hand over the distance of the knurled handle will produce merely an APPROXIMATION of a theoretical value. This is why some bolts etc. do not require "tension", but angles of required rotation. "Tension" is the screw thread (a helix, which is actually a coiled INCLINED PLANE or WEDGE) converting a "Moment"; Force x distance, to tensile load on a bolt imparted to that bolt by the thread.
@@VintageEngineRepairs I'm sorry if I am "preaching to the converted" . I've also changed my initial response to yr video. Cheers from the Hunter Valley.
It’s easy. Take your car to any chain tire store. Have them change your tires. Your wheel nuts are now torqued to 250lbs. Calibrate your tools to that.
