Originally Posted by bartman49
Is there any practical way to check a torque wrench's accuracy? I bought an inexpensive one from Harbor Freight and I worry about whether it is really accurate or does the number just give you a false sense of confidence?
It is pretty easy to "mate" one torque wrench to another using an appropriate sized socket. I don't have any 'spensive torque wrenches, but I have a few: one 1/2 drive bar-deflection type, and a couple of "clickers", 3/8" and 1/4" drive. The clickers are probably chinese vended by Northern Tool or Harbor Freight.
Just 'cuz I'm curious, some time ago, I worked one against another. I was surprised that they were pretty close.
If you have a known, good quality wrench you could get a pretty good idea how accurate your H.F. wrench is by pitting against another more trusted torque wrench. This method is only as good as the wrench you are testing against, but is simpler than setting up weights and doing calculations.
The actual torque applied to a fastener is influenced by rust, grime, grit, galled threads, lubrication, and the application of the torquing force. If you stop and start the force application, you'll get a different end result than if you apply a steady, constant force until the desired setting on the torque wrench is achieved. I suspect these variables are a bigger factor than is the accuracy of my torque wrenches.