realjimjim
Member
Anyone know an easy way to determine if a torque wrench needs to be calibrated?
Thanks!
Thanks!
Easy way to check torque wrench for calibration?
- Thread starter realjimjim
- Start date
1nterceptor
Well-known member
Easy and cheap, yes. Most accurate? Probably not:
Buy one of THESE from Harbor Freight for under $25 after discount. (strain gauge based units are very accurate, even the HF ones.)
Clamp the male end of the unit in your vise. Attach your torque wrench to the female end of the unit. Pull torque on your wrench at a few values (25%, 50%, and 75% of wrench capacity - but no lower than 20%) and compare to the digital readout.
Unless you need a lab certificate of calibration for your wrench (in which case you wouldn't be asking us), this method will be more than accurate enough for 98% of us.
Clamp the male end of the unit in your vise. Attach your torque wrench to the female end of the unit. Pull torque on your wrench at a few values (25%, 50%, and 75% of wrench capacity - but no lower than 20%) and compare to the digital readout.
Unless you need a lab certificate of calibration for your wrench (in which case you wouldn't be asking us), this method will be more than accurate enough for 98% of us.
APEowner
Well-known member
Lock the drive end in a vice and hang a known weight off the handle, measure the distance from the center of the drive to where the weight is hung and do the math.
Jagmandave
Well-known member
I have one of those HF testers set to ft lbs, and I find it to be absolutely dead on - we have a certified tester at school and it and the HF one agree on readings almost exactly.
Absent any other way it allows you to get the calibration of your torque wrench pretty damn close.
Don't forget to unwind the handle when you're done with your torque wrench, don't just toss it back in the tool box or you'll ruin your calibration.
Absent any other way it allows you to get the calibration of your torque wrench pretty damn close.
Don't forget to unwind the handle when you're done with your torque wrench, don't just toss it back in the tool box or you'll ruin your calibration.
Assuming its a cliker, you can test in in a couple of ways.
1) Use a beam wrench with a hex-bit socket
2) Use a static weight measurement, but this needs a calibrated weight.
If you don't have these as options, I would be very cautious. Friendly reminder--Don't do something stupid with an un-callibrated torque instrument.
I'd leave it to others for more input and ideas, tho.
1) Use a beam wrench with a hex-bit socket
2) Use a static weight measurement, but this needs a calibrated weight.
If you don't have these as options, I would be very cautious. Friendly reminder--Don't do something stupid with an un-callibrated torque instrument.
I'd leave it to others for more input and ideas, tho.
n8n
Well-known member
bendy-beam and the coupler from an old distributor wrench.
Not saying it wouldn't be "close enough" for most of us, but the "hanging weight" method has a LOT of variables that make it inherently less accurate:
1. Weight - Is the weight you are using a known calibrated value? Or are you using a bathroom scale to measure water in a bucket, or using a plate from your weight bench? Neither of those are going to be very accurate.
2. Distance - How accurately can you measure and hang the weight?
3. Are you taking the weight of the torque wrench itself into account? And how - the weight of the wrench is distributed along its length, not at a point source.
Again, it is probably a "close enough" check for most people. But with the digital torque adapter, you are measuring torque directly with a tool designed to measure torque. It is inherently much more accurate.
1. Weight - Is the weight you are using a known calibrated value? Or are you using a bathroom scale to measure water in a bucket, or using a plate from your weight bench? Neither of those are going to be very accurate.
2. Distance - How accurately can you measure and hang the weight?
3. Are you taking the weight of the torque wrench itself into account? And how - the weight of the wrench is distributed along its length, not at a point source.
Again, it is probably a "close enough" check for most people. But with the digital torque adapter, you are measuring torque directly with a tool designed to measure torque. It is inherently much more accurate.
After reading some reviews on the Powerbuilt 940759 I bought one on sale for $40. It's digital just like the HF one and came with an adapter so it can be easily clamped in a vise. I was amazed at how accurate it is. I had just gotten a new CDI torque wrench with a calibration certificate and tested it with this and they matched exactly! I have also done the hanging weight method but took everything, including wrenches and the line setup and weighed it at fedex. I found one 10 pound weight was actually 9.65, 5 pounders were 4.85 and 5.15 and the 25 pounders were actually 25.5. You can do good testing if you are precise with your weights and measurements but I now test only the digital with weights and then use that to test my wrenches (unless it's my inch pound wrench)
theoldwizard1
Well-known member
Yep !
I would only add, if you have a clicker, the weight should be a bucket that you slowly add sand to. Once it clicks, weigh the bucket and sand. Do the math.
JRC3
Well-known member
I didn't realize HF had such a thing. For $24 I'll have to pick one up.
It is junk, I have one and tested it. Also tested about 50 different wrenches, Snap on CDI, Craftsman and pittsburgh pro. The older craftsman were pretty good Pittsburgh were off 20 lbs
It is all over the place, most torque wrenches are a constant 5 or ten pound off that thing had no pattern. Very inaccurate consistent with the HF product line.
It is all over the place, most torque wrenches are a constant 5 or ten pound off that thing had no pattern. Very inaccurate consistent with the HF product line.
Jagmandave
Well-known member
Interesting, and yet 5 other guys said it was spot on when tested with accurate certified instruments.
Maybe your test procedure was flawed.
Maybe your test procedure was flawed.
Charles (in GA)
Well-known member
Way back on '07 we had a discussion on a product very similar to the Pittsburgh device above, marketed by Sears, except the indicator and circuitry was all contained in a multimeter looking device cabled to the transducer. It was being clearanced out by Sears as it was a poor seller. HERE IS A LINK TO THAT THREAD.
I bought one on clearance (actually two, I sold one) and quickly realized that clamping the square drive in a vise was going to damage it and mess up the chrome. I took a section of square steel tubing, bored a hole in it for a ½ square drive socket (good US made one) an had a guy at work TIG weld it in. I bead blasted it clean, primed and painted it and then I had something I could put the torque transducer in in that i could safely clamp in a vise. It is a good way of checking the torque wrench to insure it is at least close to calibration. I checked it with a couple of torque wrenches I had calibrated at work (we have a calibration room) so I know it was spot on.
Charles
I bought one on clearance (actually two, I sold one) and quickly realized that clamping the square drive in a vise was going to damage it and mess up the chrome. I took a section of square steel tubing, bored a hole in it for a ½ square drive socket (good US made one) an had a guy at work TIG weld it in. I bead blasted it clean, primed and painted it and then I had something I could put the torque transducer in in that i could safely clamp in a vise. It is a good way of checking the torque wrench to insure it is at least close to calibration. I checked it with a couple of torque wrenches I had calibrated at work (we have a calibration room) so I know it was spot on.
Charles
Just to clarify, this is the one I use, not the HF one. It also has the cover for the male end so you can put it in a vise and not mar anything. Not everything is junk at HF but I personally wouldn't buy anything precision there but to each their own.
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dannyknapp
New member
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- Dec 3, 2014
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How about take your torque wrench to a buddy's and compare to his wrench ? i.e.- torque something to 30 ft/lbs with his, see if yours reads 30. Then torque something with yours and see if his reads it. Too easy ?
Strouty
Well-known member
So for you guys using this as a torque wrench checker, why not use it to torque stuff and use your regular ratchets?
Why? You can, but regular ratchets are way shorter than torque wrenches and would be difficult to put any sizable torque on it.
Merv Himself
Member
Recently used the "old school" method by dangling weight from the handle, then came across this board (and others) where the importance of margin of error is frequently not discuseed. Admittedly, I was winded by the time I got done struggling with a 35 pound weight, but it has always worked for me and it seems so very important to use MULTIPLE WEIGHTS due to the fact that many wrenches struggle with accuracy at the lower end of scale. If my method (or math) is wrong, please let me know. You might be amazed at my results:
eschoendorff
Well-known member
Let’s say you text your TQ wrench and find it’s out of spec. How do you adjust it to bring it back into calibration specs?
torque wrenches need to be calibrated daily but just how accurate do you need to be, a regular torque wrench that been normal abuse and never check will be within 5 lbs
we calibrate our wrenches daily and our skidmore get calibrated every six months, but that just so everybody on the same page. but the average shop wrench can go a lifetime with no issues
we calibrate our wrenches daily and our skidmore get calibrated every six months, but that just so everybody on the same page. but the average shop wrench can go a lifetime with no issues
seber
Well-known member
The hanging weight is easy and accurate provided you don't forget to add the weight of the wrench handle. I use a 10 pound check weight with a pipe extension. In this case, the weight of the extension and wrench handle become very important. Put the wrench in the vise for free swing first and weigh the handle extension combination plus hanging weight at the weight attachment point. I really like the oldwizard1 one method of a bucket of sand. I think I'll try that today. Electronic scales can be very sensitive to temperature. It can be compensated for, but a cheap scale will not have that. I also ran into one that was voltage sensitive. Fixed weights are rock solid.
greg13
Well-known member
Many of the tool trucks have "torque check" gauges on the truck. No guarantee how accurate they are, but both of mine were dead on with the gauge.
anndel
Well-known member
I bring all of mine to my Snap-on driver and he has a tester on the wall behind his seat. He'll check all brands and not only SO.