# Improvised Torque Wrench

## An improvised torque wrench with a luggage scale

If you don't have a torque wrench available - or if you want to check the readings of the one you have - it is easy to improvise by using a standard wrench and a scale as indicated in the figure above.

The moment - or torque - can be calculated

T = F a                                       (1)

where

T = moment or torque (Nm, ft lbf )

F = applied force (N, lbf)

a = length of the wrench (m, ft)

Note! - Most scales in the SI unit system measures weight - force due to the acceleration of gravity - in kg.

The reading from the scale can be converted to N by using

F = m g

where

m = reading of the scale (kg, lbf)

g = acceleration of gravity (9.81 m/s2, 32.17 ft/s2)

### Example - Measuring Torque with a standard Wrench and a Luggage Scale - readings in kg

The reading of the scale at the end of the wrench is 10 kg. The length of the wrench is 0.3 m. The moment exerted can be calculated

T = (10 kg) (9.81 m/s2) (0.3 m)

= 29.4 Nm

### Example - Measuring Torque with a standard Wrench and a Luggage Scale - readings in lb

The reading of the scale at the end of the wrench is 20 lbf. The length of the wrench is 1 ft. The moment exerted can be calculated

T = (20 lbf) (1 ft)

= 20 ft lbf

### "Luggage Weight - Wrench" Online Torque Calculator

m - Scale Reading (kg, lb)

a - Wrench Length (m, in)

SI Imperial

### Scale Wrench Torque Diagram - SI units

#### Example - Torque Settings for a Cylinder Head

The torque settings for a cylinder head in a car engine are specified to 30 Nm.

According to the diagram above with a wrench with length 0.2 m - the scale readings should be approximately

14 kg

## Related Topics

• Mechanics - Forces, acceleration, displacement, vectors, motion, momentum, energy of objects and more

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