torque wrench calibration ?

[boo]

Have a question.
I have two torque wrenches.

1 - old beam and pointer type

2 -  new style pressure break type

There appears to be some difference in torque point between these two wrenches.

I plan to use when doing maintenance on variator and clutch when the maintenance is due.

How can I calibrate these tools to see which is more accurate ?.

[ScooterCommuter]

It's not going to be easy without a custom jig that they use at the factory, however here's the general principle.... use the metric scale on the wrenches, because the numbers are easier. The torque is the force applied in Newtons multiplied by the distance from the axis of rotation in meters at which it is applied. Conveniently, under 1G a 1kg weight applies a force of exactly 1N.

So, if you secure the socket attached to the wrench horizontally in a vice such that the arm of the wrench is free to rotate and is also perfectly horizontal, you can hang weights on it at a known distance from the center of its shaft and calculate exactly the torque being applied.

eg, if the shaft of your wrench were 30cm long, hanging 4kg of weight from the end of it exerts exactly (4x0.3)=1.2Nm of torque.


Edited to add, that if you are testing the pointer type this way, it's even more awkward, because the handle has to be horizontal WITH THE WEIGHTS IN PLACE because any deviation from that position means the force they apply is not perfectly tangential and that will diminish the torque produced.

[mrbios]

Don't worry about it.  You are just looking for a general value.  I put my variator nuts on with my air gun.  As the other poster mentioned you could use weights or they sell a socket insert called a torque limiter?  that is used a tire shops (ideally).  It basically slips once a given torque is reached.   Make sure you are dealing in ft-lbs not inch-pounds (micro torque wrench). 

Remember, you don't need to be real exact in this situation.    Still, I recommend torque wrenches for newbies because they don't have an idea with 20, 50, 80 etc ft-lbs "feels" like; as a result they may over or under tighten a nut or bolt.  I even use on once in a while to check my myself. 

The exception is critical parts like and engine and where all nuts / bolts must be the exact same - the head on an engine for example - you don't guess in situations. 

[boo]

It's not going to be easy without a custom jig that they use at the factory, however here's the general principle.... use the metric scale on the wrenches, because the numbers are easier. The torque is the force applied in Newtons multiplied by the distance from the axis of rotation in meters at which it is applied. Conveniently, under 1G a 1kg weight applies a force of exactly 1N.

So, if you secure the socket attached to the wrench horizontally in a vice such that the arm of the wrench is free to rotate and is also perfectly horizontal, you can hang weights on it at a known distance from the center of its shaft and calculate exactly the torque being applied.

eg, if the shaft of your wrench were 30cm long, hanging 4kg of weight from the end of it exerts exactly (4x0.3)=1.2Nm of torque.


Edited to add, that if you are testing the pointer type this way, it's even more awkward, because the handle has to be horizontal WITH THE WEIGHTS IN PLACE because any deviation from that position means the force they apply is not perfectly tangential and that will diminish the torque produced.

Do you mean like this.
Grip wrench handle one inch from the end.  Apply horizontal pressure shaft 36cmx(4x0.3) -over 9 2 xx+1g per 4kg -1.2nm will equal 874495632.1245 tangential at 45* angle with pointer at desired point on scale?.