View Full Version : torques - rough estimates for wrench ranges

03-01-2013, 08:59 PM

just bought a torque wrench which is 5-25Nm to check the torque needed to turn a shaft on a prototype. Under normal working conditions the shaft can be turned by hand, but sometimes one needs to press on the handle rather heavily to make it turn (variable levels of resistance). Currently I'm unable to use the newly bought tool as the wrench is 1/4" and the bolt on top of the shaft is M12 which means I need a 19mm socket and as it turns out a 1/4" 19mm is not available so I need a converter. I've ordered the right bits and I'm waiting for them to arrive, but in the mean time I wondered how much 5-25Nm is? one wrench size up, which is 3/8" (19mm sockets easily available) is 20-100Nm, but I've made a guess, maybe incorrectly, that this will be way above hand crank levels.

So to sum up, is 5-25Nm anywhere near hand crank / hand tightening or should I go for 20-100Nm instead? it's just that it's a bit hard imagining all these Nms.


03-01-2013, 10:33 PM
> it's just that it's a bit hard imagining all these Nms.

1Nm is the torque exerted by 1N acting on the end of a perfect pivot 1m long.

1N is the force exerted by gravity on a mass of about 102g

So imagine a (weightless) metre rule, with 102g hanging off the end of it - that's 1Nm

25Nm is 2.55kg hanging from the end of the metre ruler.

Whether that helps or not is another matter :playful:


04-01-2013, 12:19 AM
Ah yes indeed:) but what is 2.55kg hanging of a one meter ruler?:) unless I can construct a rig where a line pulls on the shaft handle and the load is variable, I'm still lost as to what it means in practical terms.