Torque spec adjustment when using extension

Can someone point me to info on how to adjust torque specifications when using various length extensions? I heard it makes a difference.

 

It also depends on angle. 90deg is no adjustment. 0deg (straight) is a ratio.

Here's a calculator for 0deg:
https://www.engineersedge.com/manufacturing_spec/calculator/torque_adapter_extension.htm

 

Perfect, thanks. I’ll take a look.

 

That might mislead him because a zero degree extension is like you stick a piece of pipe over the end of the torque wrench, right?

He probably meant extensions like what goes between the drive bit and the socket

 

Yep, this is what I'm looking for.

 

Nice call! Those are definitely in the plane of the torque wrench.

Socket extensions are zero change. Use them, except universal joint extensions. Those change torque.

 

Well I just learned something I didn't know was there to be learned!

 

I could be wrong but I don't believe a universal joint will change the torque. We use them often in aircraft work and there's no change of torque when using them.

Keep this in mind:
torque = force * distance * theta.

Force = amount of force used on the tool.
Distance = distance where force is applied from center of rotation on the rotating part.
Theta= angle of the force from the radius of the rotation of the center of the hardware using sin. Sin(90)=1.

If you had a 1 foot long tool and put 10lbs of force on it at a 90* angle then you would have 10ft/lbs torque.

Edit: extensions do not alter torque either.

 

I might have been talking out of my ass on the universals. Lemme verify that. It felt like I was remembering something though. The spider rotates through a different angle through the rotation.

If you have a double universal, that should be no change.

 

If you use anything that changes the distance between the torque wrench and where the force is applied you need to adjust for it. If the extension is 90° off from the torque wrench no adjustment is required because the distance between where the torque wrench is applying force and the actual force applied is the same.

 

This is what I thought, because it makes sense. But I thought I’d read, somewhere, something that had me believe I’d overlooked something. Such as forces lost through torsion in the 90* extension. Alas, I suppose even that wouldn’t be easily calculable due to variances in materials used from one extension to another.

 

I wasn't talking out of my ass! I know the OP clarified that he was looking for info about socket extensions.

I found the reference though. Wobble and ball-and-swivel extensions (like CV joints) can be used up to a 15deg angle. Universal joint type extensions are not allowed.

Regarding your question, most any normal socket extension will not reduce the applied torque by much at all. That said, in an operational environment, there is an allowed torque range. For example, for 1/4-28 threads, the recommended torque setting is 40in-lb with a range of 30in-lb to 40in-lb.

I have a set of 6in long allen sockets. It is a long hex in a socket head. The smaller ones, 3mm through 5mm, really flex when torquing, so they are loosing some of the torque read by the tool. I usually increase the needed torque by a bit (maybe 1N-m or 1ft-lb depending) to account for this.

If torquing something in a pattern, it is more important that everything hit the same torque more that hitting the precise torque setting.