Originally Posted by
Kontact
Your argument just shows that you don't know what torque is. 12 inch pounds is identical to 1 foot pound, which means that one 30 pound kid 6 feet from the pivot is identical to one 180 pound adult one foot from the pivot. They produce identical torque, and either will lift a 28 pound child at the other end of the board because their torque exceeds the force the 28 pounder's weight produces.
There are many reasons that Snap On would tell you not to hold the shaft, but it isn't because the torque reading is going to be different if you are putting perpendicular force on it. And anyone with a torque wrench can confirm this very easily.
If the wrench was measuring the actual torque being directly applied to the fastener, then it wouldn't matter where you grabbed the handle.
For the click wrenches, the torque is actually being indirectly sensed at the pivot point that is a couple of cm away from the axis of the fastener. IIRC, this is why the force needs to be applied at the correct location of the handle.
I've seen various explanations of this, but this Park Tool video touches on it (about 1:48 into the video)....
They have a video on their beam torque wrenches too, and I should probably review that. My Park beam torque wrenches have handles with a pivot, in order to prevent the user from applying a torsional moment at the handle.
Steve in Peoria (but never used a torque wrench on my tapered axle cranks)