Can I use one torque wrench to calibrate another?

neeb
neeb Posts: 4,473
in Workshop
So I've just bought a new Norbar torque screwdriver to cover the lower end of my torque wrench needs - it goes from 1.2Nm to 6Nm in 0.2Nm increments on the scale. I also have another Norbar torque wrench that goes from 4Nm to 20Nm in 1Nm increments that I've had for years and years and which has seen much use.

I can basically test these wrenches against each other by using a 6mm hex bit that's effectively same width at each end. Doing so, it looks like the old wrench is undertorquing by nearly 1Nm. Now, I know I can send it off to Norbar for recalibrating, which would cost a large part of the purchase value of an identical new wrench. But it has a little hole in the side (which used to have a sticker over it saying that the warranty was invalidated if removed), which, if memory serves, was for calibrating.

I guess there's no reason not to try to calibrate it myself using the other, more accurate new wrench as a reference? Does anyone know what tool I would use to do that? (it's pretty dark inside that little hole..).

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