Torque Wrench - Calibration Verification

Mr. Pink

Well-Known Member
I’ve always felt that if there is uncertainty as to a torque wrench’s accuracy, you may as well not even use it.

I came up with a quick, easy way to verify the accuracy of a torque wrench.

I welded a 1/4” coupling nut to a piece of angle iron.
Discarded bed frames are a great source of free angle iron.
Just clamping the nut in a vise tended to twist under torque.
A 1/4” nut has a 9/16” hex. This is ideal for testing 1/4”, 3/8” and 1/2” wrenches.

Weld Coupling Nut.jpg

Using a deep well socket allows you to let go of the wrench without it hitting the floor.

Deep Well.jpg

As long as the wrench’s handle is 12” long there is no math needed. For example, 25 pound weight equals 25 foot-pounds.

Handle Length.jpg

The handle on my 1/2” torque wrench is 15” long, therefore I need to multiply the weight used by 1.25.

The handle on my 1/4” torque wrench is 8” long, thus I need to multiply the weight used by 0.66.
Also, my 1/4” wrench is calibrated in inch-pounds. To convert foot-pounds to inch-pounds, multiply by 12.

Weight on Wrench.jpg

If your wrench is off by more than a couple of pounds, it should be easy enough to find a YouTube video explaining the adjustment procedure for your particular wrench.