I prefer to use a torquewrench whenever possible. Since I don't like spending money, I have bought two of the cheapest quality. (app. 20 Euro each). But to be reasonable sure of the result - I calibrate them - This is how i do:

I use a vise to fix the wrench, a kitchenscale, a container for water, paper and pencil - and a torquewrench

I need to know the load from the container

- and the length from the middle of the handle to the pivot.

- and the load from the wrench itself.

Since I also know the gravity (more or less), I am able to calculate the baseload from the container,

the string and the wrenchhandle:

Using Kg and Meter, and Gravity = 9.82m/sē, the calculation for the baseload is:

(Container + wrench) [Kg] * Wrenchlength [m] * Gravity [m/sē] = Torque [Nm]

I set a rising serie of torques, and pour water (carefully masured) until the wrench clicks.

The torque from the water is:

Water [Kg] * Wrenchlength [m] * Gravity [m/sē] = Torque [Nm]

The resulting torque is the sum of the two torqes abovementioned.

COmparing the torqe set af the scale, with this figure, I get the deviation.

The deviation i surprisingly less than 2Nm, or an max. relative deviation of app. 10% in general +/- 1Nm - not too bad!.

Should you care to se the results (texts in danish):

Little wrench

Larger wrench

To achieve app. 80Nm at the larger wrench, some 20 kg is necessary:


- some might add: "Get a life, Stig!"