you must take into account the weight of the wire and the weight of the wrench itself adding to the torque. which is why it clicked at 40. because the actual weight was slightly more than you calculated.
Great point, the weight of the wire was probably negligible, but the weight of the wrench itself was something I didn’t factor in, and honestly I have no idea how you would calculate it 😖
@@EnginesandUnfinishedBusiness weigh the thing. Figure out the centre in gravity by balancing it in a strong loop. There's where the weight is acting. Now just subtract that torque from your reading and rest accordingly. Cheers ;)
Completely unscientific, but curious about this, I took one of my dial indicating wrenches of about the same size and heft as a clicker of a similar range (1200 in/lbs), and clamped it in the vice. It indicated 60 in/lbs
at last, someone who's working in metric rather than imperial ! (my recently purchased wrench is metric only)... and we did go metric in the UK when I was still in nappies.....many, many years ago.
Indeed! I was born in the 80s, so was always taught metric stuff, yet we still use miles and stones etc. The worst is cars though, we buy fuel by the litre, but efficiency is in miles per gallon. Crazy. I can see the appeal of imperial for mental arithmetic, as thirds and quarters are easier in base 12, but I really wish the UK would go all in on metric :)
I've done this for adjusting a Toyota Hilux 2.8 L diesel engine belt to the workshop manual spec. The book reads something like "apply an 'X' Nm force to deflect the belt by 10mm (or thereabouts)". There is obviously a special tool used by the factory to do this. I thought about this for awhile and then realized that elementary 'A' level physics class on the mechanics of levers does come in useful here ! With a little bit of ingenuity and calculation adjustment, a spring scale from the local hardware shop came in very useful.
Thanks! Mine was of by more than 10 Nm. I fixed it by inserting a penny between spring and other metal parts inside the tube. Now it is of by only ~2Nm, which is great!
The only place weight can be accurately applied is centered in the designated grip area; moving it along the shaft is NOT a simple linear leverage effect, as the release/click depends on internal flexion of a beam. Weight known to be accurate can be added slowly, but only at the correct place on the handle.
Put weights, zip tie or wire AND wrench on a scale until 20lbs. is reached. Put wrench drive in a vice so the wrench sticks out horizontally. Measure out from drive towards the the handle 1ft. and mark it. Set wrench to 20 ft/lbs. Zip tie or wire the weights to the mark but dont let go. Slowly lower the weights til it clicks. If it clicks too soon or doesnt click, it needs recalibration. I got it.
I worked in a machine shop governed by aerospace parameters for nearly everything on the shop-floor ... we used Bacho torque wrenches , they had monthly calibration. Nearly every one failed and was cut in half and skipped after 3 months! It was a very high usage environment.
Instead of clamping the square drive directly in the vise, it'd be better to attach an extension to the wrench and then clamp the extension in the vise. That way, all four sides of the drive are being used and you won't mar the drive. If your vise doesn't have slots/teeth to hold round shafts, there are jaw inserts (magnetic or screw on) that allow clamping of round shafts, and if you're doing a lot of vehicle work, you're going to need them at some point anyhow.
the pivot point is NOT the point where you attach the socket. the pivot point is that little circle few cm towards the handle. if you move the weighs around the handle, you are actually "changing the torque setting". every torque wrench has a marking which shows where you should ideally apply the force in regards to the pivot point so that the torque to the socket is correct.
Thanks for the nice to the point video. I don't think it really matters metric or imperial so long as your torque wrench does what it needs to do. I sort of cheat in that all of mine have more than one force measurement listed.
finally someone who showed in metric. I cant go down to 40NM but i doubled and at 80NM the luggage showed 19+(not very precise cheap luggage scale) kg so i am fine. It was a cheap wrench.
what kind of torque wrench is that again? I want one. If it's really that cheap and stays calibrated for that long, it's better than anything I can find around here short of going to Lowe's and getting a Kobalt
It's a Draper one, looks like they even still make it :) - www.drapertools.com/product/30357/1-2inch-Square-Drive-30-210Nm-or-22-1-154-9lb-ft-Ratchet-Torque-Wrench
You are missing an important detail from physics. All torque wrenches should be in rotation when approaching and reaching the ”click”. Since the static friction or ”breakaway friction” is higher than dynamic (when you are in rotational motion), this test is not accurate. The same problem happens when people want to double check if it was torqued to spec and then trying to drive it once again and it will make the click sound almost always because now the static/breakaway friction is harder to overcome than the friction when in motion. Summary, never double check torque and always make sure you have decent rotational speed when you approach the click. If it doesn’t feel right, loosen slightly and get a new grip that is more ergonomic to make sure wrench is in motion when reaching the click.
That's a great point, and something I hadn't considered (I've also been guilty of double checking torqued bolts in the past) It'd be interesting to somehow test how much more the static friction is
Steel on steel sliding vs static friction is about double, but more than just that is going on in threaded things. Without doing any thinking, I just tightened a random bolt to 20 Nm. To get it going again only took 25 Nm. But yeah, you can't recheck a thread after it's been torqued. None of this has any relevance to the calibration.
@@peteb954 I started work in 1962 and went straight into metric. Every measurement was in m/m From .3mm upwards to over 5000 mm. It wasnt precision work.
FYI.... That is a very inaccurate way to verify a micrometer torque instrument. For starters the fulcruming action on a micrometer style torque instrument is downstream of the drive, thus making the instrument length sensitive. You'll need a digital torque tester with a First Peak mode to quantify the 1.peak drop time during the audible click. If you have a 20-100 NM torque instrument there would no way to quantify +/- 4% accuracy using you method. Either purchase a digital torque checker or send it out to be verified.
Looks a good way to check accuracy of a torque wrench for home use. Although I think your worktop that the vice is fixed to flexed when you hung the weights on the wrench? That could affect the results.
I'm gonna reply to this old comment to this old video to highlight the most important point you made. Torque wrenches don't actually measure torque directly, unfortunately. Otherwise it wouldn't matter where the force is applied. Like you say, the distance is important (and I found this out by verifying with a digital torque calibrator). So in order for this method to work, you should apply different weights all in the same location (on the handle, where you will also apply the force in use).
Sorry about a long response but your calibration test is invalid on this type of torque wrench. I will attempt to explain why in simple terms. 1. There is an inner rigid socket wrench and an outer handle. 2. The outer handle has a compression spring pressing on a roller. 3. The roller interacts with an inclined plane on the end of the inner rigid wrench. For simplicity I will refer to this and the roller as a clutch. 4. The outer handle is calibrated to apply a force to the clutch which transfers the force (F) to the rigid wrench at a fixed distance (d) from the axis of rotation. T=F x d. 5. The handle has a secondary pivot between the socket and the clutch which gives a mechanical advantage reducing the force needed to activate the clutch. 6. Therefore the force applied to the handle can vary depending on the distance from the secondary pivot, while delivering the same force to the rigid wrench via the clutch. 7. The force applied to the handle will (necessarily) be less than the force applied to the clutch. (There is an exception to this when the handle is held between the socket and the clutch). 8. As a consequence of this you cannot calibrate a click type torque wrench using weight at a distance along the handle. It will nearly always appear to be out of calibration. 9. To calibrate this type of torque wrench you need to apply and measure the torque through the socket. All the best.
I concur. I spent ages trying to get my head around this a while back, when I broke a bolt in my engine by over torquing , due to the fact I had choked down on the handle of my torque wrench. A youtube video entitled "Why GRIP Position on Torque Wrenches MATTERS!", by The Bike Sauce, explains it really well, with the maths to back it up.
FUNNY! Your calibration method is so flawed that it’s more a joke than anything else. But to be fair you are not the only one. The vast majority of people showing others how to calibrate or test their wrenches lack the understanding of how a torque wrench works and how to test it correctly, and specially of the math and physics behind their design. This is a clear example of an instant where common sense is nothing but nonsense. Here is a video of someone who is on the right track. “Most commonly than not people’s common sense is more nonsense than rational or logical sense. That’s because most people’s rational thinking is often based on irrational thinking, and their logical thinking is often based on illogical thinking. That leaves us with reasonable sense. Again, we run into the problem that most people’s reasonable thinking is often very unreasonable.” ~ Yahsnia Galiani ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0f746pF1xc0.html
Thanks for linking that video, really interesting, I love having the opportunity to learn more. The funny thing is you wax lyrical about “common sense”, even going as far as to include a pretentious quotation, yet the video you linked actually says that the way click type torque wrenches work goes against common sense, and that it took him a long time to get his head around it. It’s great to help educate people when they’re missing some information, but you’ll likely get better results in future if you do it in a less dickish manner. I learned something from your comment, I hope you can learn something from mine
