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It doesn't take much to do a rough calibration on a torque wrench.
Just grip the drive in a vice, attach a spring balance at a suitable distance and pull, observing the balance reading when the wrench clicks.
Repeat at various settings.
I usually wrap a load of tape either side of the point where the balance is attached, for accuracy and to control slippage.
And its obviously best to attach the balance somewhere near the end of the wrench handle and work in messy units of inch.lbs or Newton.millimetres and then convert to suitable round units afterwards.
Sorry if that's a bit "egg-sucking" for many readers.
As with a lot of things, its more about the technique than the equipment (missus).
I usually tighten things up in stages, particularly if the clamping area is broad with multiple fixings and/or is made of aluminium.
For example, fork bottom/wheel spindle clamps can be tightened in one hit with a torque wrench but the resultant clamping effect will be compromised as the material distorts and in a bad case the clamp will shear. In these cases I much prefer hand tightening by "feel" in the first place, increasing the torque progressively and only using the torque wrench for the final, calibrated tweek.
Same for engine cases etc.
In short, torque wrenches are more useful for controlling the final torque applied than for applying the whole torque ... unless its a single bolt fixing.
The state of cleanliness and/or lubrication of the threads is critical too.
But yes, I certainly do use a torque wrench ... nearly always.
And to avoid thread damage, I usually work to the lower end of the torque tolerance .. or sometimes even slightly less.
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