Torque wrench calibration?

[Paul G]

This may be a stupid question but I will ask anyway. How do you make sure your torque wrench is accurate? I have a 1/2" drive torque wrench I use pretty much just for torquing down wheel lug nuts. It was a cheap one from Harbor Freight. Is there a way to test it's accuracy? I need it to torque down my new heads.

[Runner]

ill bet its wayyyyy off.  from what ive seen on our tester thats calibrated every year cheap ones arent very good, infact they are usally so far off i wouldnt even bother torquing wheels with them,  sorry thats just what ive seen.   from what ive seel craftmans arnt much better. i was pretty discusted when i check mine.  i though it in the trash and bought a proto that always checks spot on.   snapon, proto, matco and mac are pretty decent.

[l8rg8r]

also always zero your torque wrench when your done that helps keep them acurate

[375instroke]

Don't zero a click type torque wrench.  Set it to the lowest setting, but not lower.  Most click types don't start at zero.  If you take all the tension off the spring inside, things will move around inside and change the calibration.

[Steve P.]

I have a high end torque wrench that I have tested over and over. Has always come up true. Then a few years ago I put it and a few other tools into my luggage and flew out to Vegas where VegasMike and I were putting together a street 440. Well we had some of the motor together and going well when I grabbed the torque wrench and set it to half of some bolts value and tightened the bolt. ((SNAP))... No it was not the wrench. It was the bolt. Well we got the remains of that bolt out and put in another.  ((SNAP))... That was it.  Evidently the people at the airlines did NOT listen to me when I told them not to crank the handle down to or past ZERO.....  I sent it to a place in Alabama or Georgia to have it repaired and calibrated.

When I was working in the NUKE field my T Wrench had to be calibrated all the time and it was allllllllways perfect..   Not that time...

[jerry]

sounds like you will be here for awhile waiting for an answere to your question as you can see.

[Steve P.]

sounds like you will be here for awhile waiting for an answere to your question as you can see.

The only good way I know of is to send it in to be calibrated. It takes a specialized scale to check it at many settings. Then you have to know how to adjust it and check it again..  I do not know of a good way to check it without this stuff..

I have checked one against a known calibrated wrench by tightening a nut on a hitch ball. First tightening the nut with the known good wrench and then going one pound less with the second wrench. If it doesn't click at this setting you move it up one pound. It should click at the same setting as the known calibrated wrench. We used to do this on the job and we did it at many setting of torque.. This is a crappy way to go about it, but if you have a known good calibrated wrench to test from it will work in a pinch. In this case if he had a KNOWN CALIBRATED WRENCH he would not be wondering about his torque wrench.

[Just 6T9 CHGR]

Here at the NYCTA we have an in house TQ wrench calibration team that comes to each depot every 3 months to calibrate our wrenches....somehow I got volunteered to handle the inventory of over 50 different wrenches when the truck comes.
The van is equipped with various fixtures & digital machines to calibrate various wrenches.

They are coming next Tuesday the 11th....if you can meet me in Brooklyn, NY then I'll see if I can get yours calibrated




EDIT----kidding of course on the meeting part   Sorry!

[69_500]

Ah I was going to say that I was free on the 11th to travel to Brooklyn to bring you my 3 wrenches if you wanted to go ahead and calibrate them for me. 

[375instroke]

If comparing two wrenches, I wouldn't check them on a torqued bolt.  All our wrenches are calibrated at my work.  Just for fun, I connected two torque wrenches together with a socket and set them to the same setting.  Turning them against each other, and they both clicked at the same time.  Set one just one inch-pound lower, and it clicked first.

[4aThrill]

I have always put torque wrenches at five or just before zero, but I didn't know if you do put it at zero it could mess up the calibration. learn something everyday